Interaction of Electromagnetic Fields with Magnetized Plasmas (2006)
This Final Scientific Report describes research at the UTK Plasma Science Laboratory which was supported by the Air Force Office of Scientific Research, contract AFOSR 89-0319, with Dr. Robert J....
Investigation of RF Emissions from Electric Field Dominated Plasmas. (1998)
Research include effort to confirm the theory of the geometric mean plasma emission. This process results from two interpenetrating electron beams in a Penning discharge. Effort were made on...
This contract has supported four research programs: 1) a program of research on plasma turbulence; 2) a program of research on plasma heating by collisional magnetic pumping; 3) a research program on...
Investigation of a Uniform Glow Discharge Plasma in Atmospheric Air. (1998)
During this year, we demonstrated the ability not only to cover the surface of a simulated aircraft fuselage with a thin layer of plasma at one atmosphere in both atmospheric air and helium, but we...
Corrosion Inhibition by Plasma Ion Implantation. (1998)
Roth, J. R., Buchanan, Raymond A.
Research Office Contract DAAL-03-89-G-0104. Accomplishments during this four year period include building up an operational plasma ion implantation facility, the successful plasma ion implantation of...
Investigation of a Uniform Glow Discharge Plasma In Atmospheric Air. (1998)
During this year, we demonstrated the ability not only to cover the surface of a simulated aircraft fuselage with a thin layer of plasma at one atmosphere in both atmospheric air and helium, but we...
The Regeneration of Ceramic Diesel Exhaust Filters by Means of Surface Plasma (1998)
Helfritch, Dennis J., Wang, Chenggang, Roth, J. R., Sherman, Daniel M.
The diesel engine is an energy-efficient power plant, but its exhaust emissions present a serious health and environmental problem. Drastic reductions of exhaust soot have been mandated throughout...
Trypsin enhancement of rotavirus infectivity: mechanism of enhancement.
Clark, S M, Roth, J R, Clark, M L, Barnett, B B, Spendlove, R S
The infectivity of most rotaviruses is enhanced by treatment with trypsin. We studied the mechanism of enhancement of examining the effect of trypsin on rotavirus infectivity, aggregation, early...
The cobalamin (coenzyme B12) biosynthetic genes of Escherichia coli.
The enteric bacterium Escherichia coli synthesizes cobalamin (coenzyme B12) only when provided with the complex intermediate cobinamide. Three cobalamin biosynthetic genes have been cloned from...
Surveying a supercoil domain by using the gamma delta resolution system in Salmonella typhimurium.
Higgins, N P, Yang, X, Fu, Q, Roth, J R
A genetic system was developed to investigate the supercoil structure of bacterial chromosomes. New res-carrying transposons were derived from MudI1734 (MudJr1 and MudJr2) and Tn10 (Tn10dGn). The...
A role for the RecF, RecJ, and SbcB proteins in the RecBCD-dependent recombination pathway is suggested on the basis of the effect of null recF, recJ, and sbcB mutations in Salmonella typhimurium on...
The cysG gene of Salmonella typhimurium is involved in synthesis of both cobalamin (B12) and siroheme (a cofactor required for SO3(2-) and NO2(2-) reductases). The failure to reduce SO3(2-) leads to...
Transposition without transposase: a spontaneous mutation in bacteria.
Transposition mutations are typically associated with the activities of transposable elements such as transposons and insertion sequences, whose mobility is dependent upon transposase enzymes that...
A new Tn10-based transposon has been constructed and used to isolate insertion mutations with tetracycline-conditional phenotypes. Classes of mutants include conditional lethal mutations, conditional...
The cob operon encodes functions needed for the biosynthesis of adenosylcobalamin (Ado-B12). Propanediol induces transcription of the cob operon and the neighboring pdu operon, which encodes proteins...
Bobik, T A, Xu, Y, Jeter, R M, Otto, K E, Roth, J R
The propanediol utilization (pdu) operon of Salmonella typhimurium encodes proteins required for the catabolism of propanediol, including a coenzyme B12-dependent propanediol dehydratase. A clone...
Genetic structure and regulation of the cysG gene in Salmonella typhimurium.
Siroheme, a cofactor of both sulfite and nitrite reductase in Salmonella typhimurium, requires the cysG gene for its synthesis. Three steps are required to synthesize siroheme from uroporphyrinogen...
The control region of the pdu/cob regulon in Salmonella typhimurium.
Chen, P, Andersson, D I, Roth, J R
The pdu operon encodes proteins for the catabolism of 1,2-propanediol; the nearby cob operon encodes enzymes for the biosynthesis of adenosyl-cobalamin (vitamin B12), a cofactor required for the use...
Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium.
Roth, J R, Lawrence, J G, Rubenfield, M, Kieffer-Higgins, S, Church, G M
Salmonella typhimurium synthesizes cobalamin (vitamin B12) de novo under anaerobic conditions. Of the 30 cobalamin synthetic genes, 25 are clustered in one operon, cob, and are arranged in three...
The ethanolamine utilization (eut) operon of Salmonella typhimurium is controlled by a positive regulatory protein (EutR) which stimulates eut operon expression in response to the simultaneous...
Salmonella recD mutations increase recombination in a short sequence transduction assay.
We have identified recD mutants of Salmonella typhimurium by their ability to support growth of phage P22 abc (anti-RecBCD) mutants, whose growth is prevented by normal host RecBCD function. As in...
Evidence for two NAD kinases in Salmonella typhimurium.
The electron-carrying cofactor NADP is formed by phosphorylation of NAD. A strategy for the isolation of NAD kinase mutants revealed two classes of temperature-sensitive mutations, nadF and nadG,...
Escalante-Semerena, J C, Johnson, M G, Roth, J R
A detailed deletion map of the CobII and CobIII regions of the cobalamin biosynthetic (cob) operon of Salmonella typhimurium LT2 has been constructed. The CobII region encodes functions needed for...
A Salmonella typhimurium cobalamin-deficient mutant blocked in 1-amino-2-propanol synthesis.
Salmonella typhimurium synthesizes cobalamin (vitamin B12) when grown under anaerobic conditions. All but one of the biosynthetic genes (cob) are located in a single operon which includes genes...
A single regulatory gene integrates control of vitamin B12 synthesis and propanediol degradation.
Bobik, T A, Ailion, M, Roth, J R
The cob operon of Salmonella typhimurium encodes enzymes required for synthesis of adenosyl-cobalamin (vitamin B12). The pdu operon encodes enzymes needed for use of propanediol as a carbon source,...
Ailion, M, Bobik, T A, Roth, J R
The genes for cobalamin (vitamin B12) biosynthesis (cob) are coregulated with genes for degradation of propanediol (pdu). Both the cob and pdu operons are induced by propanediol by means of a...
The nadI region of Salmonella typhimurium encodes a bifunctional regulatory protein.
Mutants of the nadI and pnuA genes were independently isolated on the basis of defects in repression of NAD biosynthetic genes and defects in transport nicotinamide mononucleotide (NMN). The...
Activity of the nicotinamide mononucleotide transport system is regulated in Salmonella typhimurium.
Zhu, N, Olivera, B M, Roth, J R
Transport of nicotinamide mononucleotide (NMN) requires two functions, NadI(T) and PnuC. The PnuC protein is membrane associated, as judged by isolation of active TnphoA gene fusions and...
The genes required for use of ethanolamine as a carbon and nitrogen source are encoded by a single operon (eut) whose expression is induced by the simultaneous presence of both ethanolamine and...
Escalante-Semerena, J C, Suh, S J, Roth, J R
Salmonella typhimurium is able to synthesize cobalamin (B12) under anaerobic growth conditions. The previously described cobalamin biosynthetic mutations (phenotypic classes CobI, CobII, and CobIII)...
Synthesis of thiamine in Salmonella typhimurium independent of the purF function.
In Salmonella typhimurium, the first five steps in purine biosynthesis also serve as the first steps in the biosynthesis of the pyrimidine moiety of thiamine (vitamin B1). Strains with null mutations...
recB and recC genes of Salmonella typhimurium.
We have investigated the genetic organization of the recB (exonuclease V) and recC (exonuclease V) genes of Salmonella typhimurium. A detailed genetic map is constructed that includes the relative...
DNA ligase and the pyridine nucleotide cycle in Salmonella typhimurium.
Park, U E, Olivera, B M, Hughes, K T, Roth, J R, Hillyard, D R
Bacterial DNA ligases use NAD as an energy source. In this study we addressed two questions about these enzymes. First, what is the physiological consequence of completely removing the NAD-dependent...
Functions required for vitamin B12-dependent ethanolamine utilization in Salmonella typhimurium.
When B12 is available, Salmonella typhimurium can degrade ethanolamine to provide a source of carbon and nitrogen. B12 is essential since it is a cofactor for ethanolamine ammonia-lyase, the first...
Zhu, N, Olivera, B M, Roth, J R
The pnuC gene, which encodes a component of the nicotinamide mononucleotide transport system, has been mapped and oriented. The gene order of the pnuC region, which is at min 17 of the Salmonella...
Mutations affecting regulation of cobinamide biosynthesis in Salmonella typhimurium.
Transcription of the genes for cobalamin biosynthesis is reduced during aerobic growth. We isolated and characterized mutants that showed a 2- to 90-fold increase in aerobic expression of the...
Redox regulation of the genes for cobinamide biosynthesis in Salmonella typhimurium.
Transcription of the cobinamide biosynthetic genes (the CobI operon) was induced under three different physiological conditions: anaerobiosis (anaerobic respiration or fermentation), aerobic...
Zhu, N, Olivera, B M, Roth, J R
Mutations at the nadI locus affect expression of the first two genes of NAD synthesis, nadA and nadB, which are unlinked. Genetic data imply that the regulatory effects of nadI mutations are not due...
Structural gene for NAD synthetase in Salmonella typhimurium.
Hughes, K T, Olivera, B M, Roth, J R
We have identified the structural gene for NAD synthetase, which catalyzes the final metabolic step in NAD biosynthesis. This gene, designated nadE, is located between gdh and nit at 27 min on the...
Salmonella typhimurium mutants lacking NAD pyrophosphatase.
Park, U E, Roth, J R, Olivera, B M
NAD can serve as both a purine and a pyridine source for Salmonella typhimurium. Exogenous NAD is rapidly broken down into nicotinamide mononucleotide and AMP by an NAD pyrophosphatase, the first...
Ethanolamine utilization in Salmonella typhimurium.
Ethanolamine can serve as the sole source of carbon and nitrogen for Salmonella typhimurium if vitamin B12 is present to serve as a cofactor. The pathway for ethanolamine utilization has been...
Rec dependence of mu transposition from P22-transduced fragments.
Hughes, K T, Olivera, B M, Roth, J R
Derivatives of bacteriophage Mu carrying a lac operon and a selectable drug resistance element (Mu d phages) are frequently used tools of bacterial genetics. Mu d prophages used in this way can be...
Regulation of cobalamin biosynthetic operons in Salmonella typhimurium.
Escalante-Semerena, J C, Roth, J R
Transcription of cobalamin (cob) biosynthetic genes in Salmonella typhimurium is repressed by cobalamin and by molecular oxygen. These genes seem to be subject to catabolite repression, and they are...
Gene location affects expression level in Salmonella typhimurium.
Directed translocation of an expressed gene (hisD) provided strains to test for position effects on gene expression in Salmonella typhimurium. The predominant position effect seems to be caused by...
Cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium.
The enteric bacterium Salmonella typhimurium synthesizes cobalamin (vitamin B12) de novo only under anaerobic growth conditions. We initiated a genetic analysis of the cobalamin biosynthetic (cob)...
Genetic characterization and regulation of the nadB locus of Salmonella typhimurium.
Cookson, B T, Olivera, B M, Roth, J R
The nadB locus encodes the first enzyme of NAD synthesis. It has been reported that this gene and nadA are regulated by a positive regulatory protein encoded in the nadB region. In pursuing this...
Conditionally transposition-defective derivative of Mu d1(Amp Lac).
A Mu d1 derivative is described which is useful for genetic manipulation of Mu-lac fusion insertions. A double mutant of the specialized transducing phage Mu d1(Amp Lac c62ts) was isolated which is...
Jeter, R M, Olivera, B M, Roth, J R
In this paper, we report that the enteric bacterium Salmonella typhimurium synthesized cobalamin de novo under anaerobic culture conditions. Aerobically, metE mutants of S. typhimurium need either...
The genes for proline utilization were fused to the structural genes of the lac operon by use of the hybrid Mu phage derivative Mu d(Ap lac). Stable deletion derivatives of these fusions were...
6-Aminonicotinamide-resistant mutants of Salmonella typhimurium.
Hughes, K T, Cookson, B T, Ladika, D, Olivera, B M, Roth, J R
Resistance to the nicotinamide analog 6-aminonicotinamide has been used to identify the following three new classes of mutants in pyridine nucleotide metabolism. (i) pncX mutants have Tn10 insertion...
Mutations in the spoT gene of Salmonella typhimurium: effects on his operon expression.
Rudd, K E, Bochner, B R, Cashel, M, Roth, J R
The spoT gene of Salmonella typhimurium has been identified. Mutations in spoT map between gltC and pyrE at 79 min. The spoT1 mutant has elevated levels of guanosine 5'-diphosphate-3'-diphosphate...
Internal promoters of the his operon in Salmonella typhimurium.
Two internal promoters in the his operon of Salmonella typhimurium have been precisely mapped genetically. The internal promoters are found in, or very close to, gene border regions in the his...
Transfer ribonucleic acid methylase deficiency found in UGA supressor strains.
Extracts of recessive UGA suppressor strains, designated supK, are deficient in transfer ribonucleic acid (tRNA)-methylating activity when compared to wild-type extracts. Moreover, the tRNA from...
UGA suppressor that maps within a cluster of ribosomal protein genes.
A suppressor of UGA mutations (supU) maps near or within a cluster of ribosomal protein genes at 72 min on the Salmonella typhimurium genetic map. The suppressor is relatively inefficient, and its...
Transposon Tn10 provides a promoter for transcription of adjacent sequences.
Ciampi, M S, Schmid, M B, Roth, J R
Promoters located within the Tn10 insertion element cause transcription of "host" sequences adjacent to both ends of the inserted Tn10 element. These promoters are usually not observed in genetic...
Model for regulation of the histidine operon of Salmonella.
Johnston, H M, Barnes, W M, Chumley, F G, Bossi, L, Roth, J R
A model is proposed that accounts for regulation of the histidine operon by a mechanism involving alternative configuration of mRNA secondary structure (the alternative stem model). New evidence for...
Regulation of Tn5 transposition in Salmonella typhimurium.
The drug-resistance element Tn5 transposes with high frequency immediately after entry into a cell. Establishment of Tn5 within a cell results in a decrease in this transposition frequency. This...
Regulation of histidine operon does not require hisG enzyme.
Scott, J F, Roth, J R, Artz, S W
Mutations are described which delete all or part of the first structural gene (hisG) of the histidine operon of Salmonella typhimurium. Physiological regulation of histidine enzymes occurs normally...
An indispensable gene for NAD biosynthesis in Salmonella typhimurium.
Hughes, K T, Ladika, D, Roth, J R, Olivera, B M
We have located the nadD locus between lip and leuS at 14 min on the Salmonella typhimurium chromosome, and we have shown it to be the structural gene for nicotinic acid mononucleotide...
Polarity Effects in the Hisg Gene of Salmonella Require a Site within the Coding Sequence
A single site in the middle of the coding sequence of the hisG gene of Salmonella is required for most of the polar effect of mutations in this gene. Nonsense and insertion mutations mapping upstream...
A genetic complementation system is described in which the complementing components are close together in a single linear DNA fragment; the complementation situation is temporary. This system is...
Reciprocality of Recombination Events That Rearrange the Chromosome
We describe a genetic system for studying the reciprocality of chromosomal recombination; all substrates and recombination functions involved are provided exclusively by the bacterial chromosome. The...
Activation of Silent Genes by Transposons Tn5 and Tn10
The presence of transposons Tn10 or Tn5 in the genome increases the frequency with which a silent (promoter-less) gene (hisD) is mutationally activated. The activation frequency is increased...
The role of recBC functions has been tested for three types of chromosomal recombination events: (1) recombination between direct repeats to generate a deletion, (2) recombination between a small...
Sequences placed in inverse order at particular chromosome sites (permissive) recombine to generate an inversion; the same sequences, placed at other sites (nonpermissive) interact recombinationally...
Duplication-containing cells are selected when growth of Salmonella typhimurium is limited by the availability of any one of several carbon and energy sources. Under conditions of extreme starvation,...
A Genetic Characterization of the Nadc Gene of Salmonella Typhimurium
Hughes, K. T., Roth, J. R., Olivera, B. M.
The nadC gene of Salmonella encodes the pyridine biosynthetic enzyme PRPP-quinolinate phosphoribosyltransferase. Using a combination of genetic techniques, a deletion map for the Salmonella nadC gene...
Homologous recombination between sequences present in inverse order within the same chromosome can result in inversion formation. We have previously shown that inverse order sequences at some sites...
Lethal Transposition of Mud Phages in Rec(-) Strains of Salmonella Typhimurium
Sonti, R. V., Keating, D. H., Roth, J. R.
Under several circumstances, the frequency with which Mud prophages form lysogens is apparently reduced in rec strains of Salmonella typhimurium. Lysogen formation by a MudI genome (37 kb) injected...
In standard bacterial recombination assays, a linear fragment of DNA is transferred to a recipient cell and, at most, a single selected recombinant type is recovered from each merozygote. This...
Miesel, L., Segall, A., Roth, J. R.
Homologous sequences placed in inverse order at particular separated sites in the bacterial chromosome (termed ``permissive'') can recombine to form an inversion of the intervening chromosome...
Spontaneous tandem chromosomal duplications are common in populations of Escherichia coli and Salmonella typhimurium. They range in frequency for a given locus from 10(-2) to 10(-4) and probably form...
We have examined the distribution of cobalamin (coenzyme B(12)) synthetic ability and cobalamin-dependent metabolism among enteric bacteria. Most species of enteric bacteria tested synthesize...
A Search for a General Phenomenon of Adaptive Mutability
The most prominent systems for the study of adaptive mutability depend on the specialized activities of genetic elements like bacteriophage Mu and the F plasmid. Searching for general adaptive...
Selfish Operons: Horizontal Transfer May Drive the Evolution of Gene Clusters
A model is presented whereby the formation of gene clusters in bacteria is mediated by transfer of DNA within and among taxa. Bacterial operons are typically composed of genes whose products...
Pathways for Homologous Recombination between Chromosomal Direct Repeats in Salmonella Typhimurium
Homologous recombination pathways probably evolved primarily to accomplish chromosomal repair and the formation and resolution of duplications by sister-chromosome exchanges. Various DNA lesions...
A Refined Map of the hisG Gene of SALMONELLA TYPHIMURIUM
Hoppe, I., Johnston, H. M., Biek, D., Roth, J. R.
The hisG gene is the most operator-proximal structural gene of the histidine operon; it encodes the feedback-inhibitable first enzyme of the biosynthetic pathway. Previously, hisG mutants were mapped...
Trypsin enhancement of rotavirus infectivity: mechanism of enhancement.
Clark, S M, Roth, J R, Clark, M L, Barnett, B B, Spendlove, R S
The infectivity of most rotaviruses is enhanced by treatment with trypsin. We studied the mechanism of enhancement of examining the effect of trypsin on rotavirus infectivity, aggregation, early...
The cobalamin (coenzyme B12) biosynthetic genes of Escherichia coli.
The enteric bacterium Escherichia coli synthesizes cobalamin (coenzyme B12) only when provided with the complex intermediate cobinamide. Three cobalamin biosynthetic genes have been cloned from...
Surveying a supercoil domain by using the gamma delta resolution system in Salmonella typhimurium.
Higgins, N P, Yang, X, Fu, Q, Roth, J R
A genetic system was developed to investigate the supercoil structure of bacterial chromosomes. New res-carrying transposons were derived from MudI1734 (MudJr1 and MudJr2) and Tn10 (Tn10dGn). The...
A role for the RecF, RecJ, and SbcB proteins in the RecBCD-dependent recombination pathway is suggested on the basis of the effect of null recF, recJ, and sbcB mutations in Salmonella typhimurium on...
The cysG gene of Salmonella typhimurium is involved in synthesis of both cobalamin (B12) and siroheme (a cofactor required for SO3(2-) and NO2(2-) reductases). The failure to reduce SO3(2-) leads to...
Transposition without transposase: a spontaneous mutation in bacteria.
Transposition mutations are typically associated with the activities of transposable elements such as transposons and insertion sequences, whose mobility is dependent upon transposase enzymes that...
A new Tn10-based transposon has been constructed and used to isolate insertion mutations with tetracycline-conditional phenotypes. Classes of mutants include conditional lethal mutations, conditional...
The cob operon encodes functions needed for the biosynthesis of adenosylcobalamin (Ado-B12). Propanediol induces transcription of the cob operon and the neighboring pdu operon, which encodes proteins...
Bobik, T A, Xu, Y, Jeter, R M, Otto, K E, Roth, J R
The propanediol utilization (pdu) operon of Salmonella typhimurium encodes proteins required for the catabolism of propanediol, including a coenzyme B12-dependent propanediol dehydratase. A clone...
Genetic structure and regulation of the cysG gene in Salmonella typhimurium.
Siroheme, a cofactor of both sulfite and nitrite reductase in Salmonella typhimurium, requires the cysG gene for its synthesis. Three steps are required to synthesize siroheme from uroporphyrinogen...
The control region of the pdu/cob regulon in Salmonella typhimurium.
Chen, P, Andersson, D I, Roth, J R
The pdu operon encodes proteins for the catabolism of 1,2-propanediol; the nearby cob operon encodes enzymes for the biosynthesis of adenosyl-cobalamin (vitamin B12), a cofactor required for the use...
Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium.
Roth, J R, Lawrence, J G, Rubenfield, M, Kieffer-Higgins, S, Church, G M
Salmonella typhimurium synthesizes cobalamin (vitamin B12) de novo under anaerobic conditions. Of the 30 cobalamin synthetic genes, 25 are clustered in one operon, cob, and are arranged in three...
The ethanolamine utilization (eut) operon of Salmonella typhimurium is controlled by a positive regulatory protein (EutR) which stimulates eut operon expression in response to the simultaneous...
Salmonella recD mutations increase recombination in a short sequence transduction assay.
We have identified recD mutants of Salmonella typhimurium by their ability to support growth of phage P22 abc (anti-RecBCD) mutants, whose growth is prevented by normal host RecBCD function. As in...
Evidence for two NAD kinases in Salmonella typhimurium.
The electron-carrying cofactor NADP is formed by phosphorylation of NAD. A strategy for the isolation of NAD kinase mutants revealed two classes of temperature-sensitive mutations, nadF and nadG,...
Escalante-Semerena, J C, Johnson, M G, Roth, J R
A detailed deletion map of the CobII and CobIII regions of the cobalamin biosynthetic (cob) operon of Salmonella typhimurium LT2 has been constructed. The CobII region encodes functions needed for...
A Salmonella typhimurium cobalamin-deficient mutant blocked in 1-amino-2-propanol synthesis.
Salmonella typhimurium synthesizes cobalamin (vitamin B12) when grown under anaerobic conditions. All but one of the biosynthetic genes (cob) are located in a single operon which includes genes...
A single regulatory gene integrates control of vitamin B12 synthesis and propanediol degradation.
Bobik, T A, Ailion, M, Roth, J R
The cob operon of Salmonella typhimurium encodes enzymes required for synthesis of adenosyl-cobalamin (vitamin B12). The pdu operon encodes enzymes needed for use of propanediol as a carbon source,...
Ailion, M, Bobik, T A, Roth, J R
The genes for cobalamin (vitamin B12) biosynthesis (cob) are coregulated with genes for degradation of propanediol (pdu). Both the cob and pdu operons are induced by propanediol by means of a...
The nadI region of Salmonella typhimurium encodes a bifunctional regulatory protein.
Mutants of the nadI and pnuA genes were independently isolated on the basis of defects in repression of NAD biosynthetic genes and defects in transport nicotinamide mononucleotide (NMN). The...
Activity of the nicotinamide mononucleotide transport system is regulated in Salmonella typhimurium.
Zhu, N, Olivera, B M, Roth, J R
Transport of nicotinamide mononucleotide (NMN) requires two functions, NadI(T) and PnuC. The PnuC protein is membrane associated, as judged by isolation of active TnphoA gene fusions and...
The genes required for use of ethanolamine as a carbon and nitrogen source are encoded by a single operon (eut) whose expression is induced by the simultaneous presence of both ethanolamine and...
Escalante-Semerena, J C, Suh, S J, Roth, J R
Salmonella typhimurium is able to synthesize cobalamin (B12) under anaerobic growth conditions. The previously described cobalamin biosynthetic mutations (phenotypic classes CobI, CobII, and CobIII)...
Synthesis of thiamine in Salmonella typhimurium independent of the purF function.
In Salmonella typhimurium, the first five steps in purine biosynthesis also serve as the first steps in the biosynthesis of the pyrimidine moiety of thiamine (vitamin B1). Strains with null mutations...
recB and recC genes of Salmonella typhimurium.
We have investigated the genetic organization of the recB (exonuclease V) and recC (exonuclease V) genes of Salmonella typhimurium. A detailed genetic map is constructed that includes the relative...
DNA ligase and the pyridine nucleotide cycle in Salmonella typhimurium.
Park, U E, Olivera, B M, Hughes, K T, Roth, J R, Hillyard, D R
Bacterial DNA ligases use NAD as an energy source. In this study we addressed two questions about these enzymes. First, what is the physiological consequence of completely removing the NAD-dependent...
Functions required for vitamin B12-dependent ethanolamine utilization in Salmonella typhimurium.
When B12 is available, Salmonella typhimurium can degrade ethanolamine to provide a source of carbon and nitrogen. B12 is essential since it is a cofactor for ethanolamine ammonia-lyase, the first...
Zhu, N, Olivera, B M, Roth, J R
The pnuC gene, which encodes a component of the nicotinamide mononucleotide transport system, has been mapped and oriented. The gene order of the pnuC region, which is at min 17 of the Salmonella...
Mutations affecting regulation of cobinamide biosynthesis in Salmonella typhimurium.
Transcription of the genes for cobalamin biosynthesis is reduced during aerobic growth. We isolated and characterized mutants that showed a 2- to 90-fold increase in aerobic expression of the...
Redox regulation of the genes for cobinamide biosynthesis in Salmonella typhimurium.
Transcription of the cobinamide biosynthetic genes (the CobI operon) was induced under three different physiological conditions: anaerobiosis (anaerobic respiration or fermentation), aerobic...
Zhu, N, Olivera, B M, Roth, J R
Mutations at the nadI locus affect expression of the first two genes of NAD synthesis, nadA and nadB, which are unlinked. Genetic data imply that the regulatory effects of nadI mutations are not due...
Structural gene for NAD synthetase in Salmonella typhimurium.
Hughes, K T, Olivera, B M, Roth, J R
We have identified the structural gene for NAD synthetase, which catalyzes the final metabolic step in NAD biosynthesis. This gene, designated nadE, is located between gdh and nit at 27 min on the...
Salmonella typhimurium mutants lacking NAD pyrophosphatase.
Park, U E, Roth, J R, Olivera, B M
NAD can serve as both a purine and a pyridine source for Salmonella typhimurium. Exogenous NAD is rapidly broken down into nicotinamide mononucleotide and AMP by an NAD pyrophosphatase, the first...
Ethanolamine utilization in Salmonella typhimurium.
Ethanolamine can serve as the sole source of carbon and nitrogen for Salmonella typhimurium if vitamin B12 is present to serve as a cofactor. The pathway for ethanolamine utilization has been...
Rec dependence of mu transposition from P22-transduced fragments.
Hughes, K T, Olivera, B M, Roth, J R
Derivatives of bacteriophage Mu carrying a lac operon and a selectable drug resistance element (Mu d phages) are frequently used tools of bacterial genetics. Mu d prophages used in this way can be...
Regulation of cobalamin biosynthetic operons in Salmonella typhimurium.
Escalante-Semerena, J C, Roth, J R
Transcription of cobalamin (cob) biosynthetic genes in Salmonella typhimurium is repressed by cobalamin and by molecular oxygen. These genes seem to be subject to catabolite repression, and they are...
Gene location affects expression level in Salmonella typhimurium.
Directed translocation of an expressed gene (hisD) provided strains to test for position effects on gene expression in Salmonella typhimurium. The predominant position effect seems to be caused by...
Cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium.
The enteric bacterium Salmonella typhimurium synthesizes cobalamin (vitamin B12) de novo only under anaerobic growth conditions. We initiated a genetic analysis of the cobalamin biosynthetic (cob)...
Genetic characterization and regulation of the nadB locus of Salmonella typhimurium.
Cookson, B T, Olivera, B M, Roth, J R
The nadB locus encodes the first enzyme of NAD synthesis. It has been reported that this gene and nadA are regulated by a positive regulatory protein encoded in the nadB region. In pursuing this...
Conditionally transposition-defective derivative of Mu d1(Amp Lac).
A Mu d1 derivative is described which is useful for genetic manipulation of Mu-lac fusion insertions. A double mutant of the specialized transducing phage Mu d1(Amp Lac c62ts) was isolated which is...
Jeter, R M, Olivera, B M, Roth, J R
In this paper, we report that the enteric bacterium Salmonella typhimurium synthesized cobalamin de novo under anaerobic culture conditions. Aerobically, metE mutants of S. typhimurium need either...
The genes for proline utilization were fused to the structural genes of the lac operon by use of the hybrid Mu phage derivative Mu d(Ap lac). Stable deletion derivatives of these fusions were...
6-Aminonicotinamide-resistant mutants of Salmonella typhimurium.
Hughes, K T, Cookson, B T, Ladika, D, Olivera, B M, Roth, J R
Resistance to the nicotinamide analog 6-aminonicotinamide has been used to identify the following three new classes of mutants in pyridine nucleotide metabolism. (i) pncX mutants have Tn10 insertion...
An indispensable gene for NAD biosynthesis in Salmonella typhimurium.
Hughes, K T, Ladika, D, Roth, J R, Olivera, B M
We have located the nadD locus between lip and leuS at 14 min on the Salmonella typhimurium chromosome, and we have shown it to be the structural gene for nicotinic acid mononucleotide...
Mutations in the spoT gene of Salmonella typhimurium: effects on his operon expression.
Rudd, K E, Bochner, B R, Cashel, M, Roth, J R
The spoT gene of Salmonella typhimurium has been identified. Mutations in spoT map between gltC and pyrE at 79 min. The spoT1 mutant has elevated levels of guanosine 5'-diphosphate-3'-diphosphate...
Internal promoters of the his operon in Salmonella typhimurium.
Two internal promoters in the his operon of Salmonella typhimurium have been precisely mapped genetically. The internal promoters are found in, or very close to, gene border regions in the his...
Transfer ribonucleic acid methylase deficiency found in UGA supressor strains.
Extracts of recessive UGA suppressor strains, designated supK, are deficient in transfer ribonucleic acid (tRNA)-methylating activity when compared to wild-type extracts. Moreover, the tRNA from...
UGA suppressor that maps within a cluster of ribosomal protein genes.
A suppressor of UGA mutations (supU) maps near or within a cluster of ribosomal protein genes at 72 min on the Salmonella typhimurium genetic map. The suppressor is relatively inefficient, and its...
Transposon Tn10 provides a promoter for transcription of adjacent sequences.
Ciampi, M S, Schmid, M B, Roth, J R
Promoters located within the Tn10 insertion element cause transcription of "host" sequences adjacent to both ends of the inserted Tn10 element. These promoters are usually not observed in genetic...
Model for regulation of the histidine operon of Salmonella.
Johnston, H M, Barnes, W M, Chumley, F G, Bossi, L, Roth, J R
A model is proposed that accounts for regulation of the histidine operon by a mechanism involving alternative configuration of mRNA secondary structure (the alternative stem model). New evidence for...
Regulation of Tn5 transposition in Salmonella typhimurium.
The drug-resistance element Tn5 transposes with high frequency immediately after entry into a cell. Establishment of Tn5 within a cell results in a decrease in this transposition frequency. This...
Regulation of histidine operon does not require hisG enzyme.
Scott, J F, Roth, J R, Artz, S W
Mutations are described which delete all or part of the first structural gene (hisG) of the histidine operon of Salmonella typhimurium. Physiological regulation of histidine enzymes occurs normally...
Polarity Effects in the Hisg Gene of Salmonella Require a Site within the Coding Sequence
A single site in the middle of the coding sequence of the hisG gene of Salmonella is required for most of the polar effect of mutations in this gene. Nonsense and insertion mutations mapping upstream...
A genetic complementation system is described in which the complementing components are close together in a single linear DNA fragment; the complementation situation is temporary. This system is...
Reciprocality of Recombination Events That Rearrange the Chromosome
We describe a genetic system for studying the reciprocality of chromosomal recombination; all substrates and recombination functions involved are provided exclusively by the bacterial chromosome. The...
Activation of Silent Genes by Transposons Tn5 and Tn10
The presence of transposons Tn10 or Tn5 in the genome increases the frequency with which a silent (promoter-less) gene (hisD) is mutationally activated. The activation frequency is increased...
The role of recBC functions has been tested for three types of chromosomal recombination events: (1) recombination between direct repeats to generate a deletion, (2) recombination between a small...
Sequences placed in inverse order at particular chromosome sites (permissive) recombine to generate an inversion; the same sequences, placed at other sites (nonpermissive) interact recombinationally...
Duplication-containing cells are selected when growth of Salmonella typhimurium is limited by the availability of any one of several carbon and energy sources. Under conditions of extreme starvation,...
A Genetic Characterization of the Nadc Gene of Salmonella Typhimurium
Hughes, K. T., Roth, J. R., Olivera, B. M.
The nadC gene of Salmonella encodes the pyridine biosynthetic enzyme PRPP-quinolinate phosphoribosyltransferase. Using a combination of genetic techniques, a deletion map for the Salmonella nadC gene...
Homologous recombination between sequences present in inverse order within the same chromosome can result in inversion formation. We have previously shown that inverse order sequences at some sites...
Lethal Transposition of Mud Phages in Rec(-) Strains of Salmonella Typhimurium
Sonti, R. V., Keating, D. H., Roth, J. R.
Under several circumstances, the frequency with which Mud prophages form lysogens is apparently reduced in rec strains of Salmonella typhimurium. Lysogen formation by a MudI genome (37 kb) injected...
In standard bacterial recombination assays, a linear fragment of DNA is transferred to a recipient cell and, at most, a single selected recombinant type is recovered from each merozygote. This...
Miesel, L., Segall, A., Roth, J. R.
Homologous sequences placed in inverse order at particular separated sites in the bacterial chromosome (termed ``permissive'') can recombine to form an inversion of the intervening chromosome...
Spontaneous tandem chromosomal duplications are common in populations of Escherichia coli and Salmonella typhimurium. They range in frequency for a given locus from 10(-2) to 10(-4) and probably form...
We have examined the distribution of cobalamin (coenzyme B(12)) synthetic ability and cobalamin-dependent metabolism among enteric bacteria. Most species of enteric bacteria tested synthesize...
A Search for a General Phenomenon of Adaptive Mutability
The most prominent systems for the study of adaptive mutability depend on the specialized activities of genetic elements like bacteriophage Mu and the F plasmid. Searching for general adaptive...
Selfish Operons: Horizontal Transfer May Drive the Evolution of Gene Clusters
A model is presented whereby the formation of gene clusters in bacteria is mediated by transfer of DNA within and among taxa. Bacterial operons are typically composed of genes whose products...
Pathways for Homologous Recombination between Chromosomal Direct Repeats in Salmonella Typhimurium
Homologous recombination pathways probably evolved primarily to accomplish chromosomal repair and the formation and resolution of duplications by sister-chromosome exchanges. Various DNA lesions...
A Refined Map of the hisG Gene of SALMONELLA TYPHIMURIUM
Hoppe, I., Johnston, H. M., Biek, D., Roth, J. R.
The hisG gene is the most operator-proximal structural gene of the histidine operon; it encodes the feedback-inhibitable first enzyme of the biosynthetic pathway. Previously, hisG mutants were mapped...