Michael L. Vasil

The Metal-Dependent Regulators FurA and FurB from Mycobacterium Tuberculosis (2008)

Debora Lucarelli, Michael L. Vasil, Wolfram Meyer-Klaucke, Ehmke Pohl

The ferric uptake regulators (Fur) form a large family of bacterial metalactivated DNA-binding proteins that control a diverse set of genes at the transcriptional level. Mycobacterium tuberculosis,...

FpvB, an alternative type I ferripyoverdine receptor of Pseudomonas aeruginosa (2004)

Ghysels, Bart, Dieu, Bui Thi Min, Beatson, Scott A., Pirnay, Jean-Paul, Ochsner, Urs A., Vasil, Michael L., ...

Under conditions of iron limitation, Pseudomonas aeruginosa secretes a high-affinity siderophore pyoverdine to scavenge Fe(III) in the extracellular environment and shuttle it into the cell. Uptake...

FpvB, an alternative type I ferripyoverdine receptor of Pseudomonas aeruginosa (2004)

Ghysels, Bart, Dieu, Bui Thi Min, Beatson, Scott A., Pirnay, Jean-Paul, Ochsner, Urs A., Vasil, Michael L., ...

Under conditions of iron limitation, Pseudomonas aeruginosa secretes a high-affinity siderophore pyoverdine to scavenge Fe(III) in the extracellular environment and shuttle it into the cell. Uptake...

Genetic and Physiological Characterization of ohr, Encoding a Protein Involved in Organic Hydroperoxide Resistance (2000)

In Pseudomonas Aeruginosa, Urs A. Ochsner, Daniel J. Hassett, Michael L. Vasil

The ohr (organic hydroperoxide resistance) gene product of Pseudomonas aeruginosa was essential for optimal resistance to organic hydroperoxides (OHPs) but not to hydrogen peroxide or paraquat. A...

Pseudomonas aeruginosa fur Overlaps with a Gene Encoding a Novel Outer Membrane Lipoprotein, OmlA

Ochsner, Urs A., Vasil, Adriana I., Johnson, Zaiga, Vasil, Michael L.

A novel outer membrane lipoprotein in Pseudomonas aeruginosa is encoded by the omlA gene, which was identified immediately upstream of the fur (ferric uptake regulator) gene. The omlA and fur genes...

Bacterioferritin A Modulates Catalase A (KatA) Activity and Resistance to Hydrogen Peroxide in Pseudomonas aeruginosa

Ma, Ju-Fang, Ochsner, Urs A., Klotz, Martin G., Nanayakkara, Vagira K., Howell, Michael L., Johnson, Zaiga, ...

We have cloned a 3.6-kb genomic DNA fragment from Pseudomonas aeruginosa harboring the rpoA, rplQ, katA, and bfrA genes. These loci are predicted to encode, respectively, (i) the α subunit of RNA...

The pvc Gene Cluster of Pseudomonas aeruginosa: Role in Synthesis of the Pyoverdine Chromophore and Regulation by PtxR and PvdS

Stintzi, Alain, Johnson, Zaiga, Stonehouse, Martin, Ochsner, Urs, Meyer, Jean-Marie, Vasil, Michael L., ...

A putative operon of four genes implicated in the synthesis of the chromophore moiety of the Pseudomonas aeruginosa siderophore pyoverdine, dubbed pvcABCD (where pvc stands for pyoverdine...

Role of the Pseudomonas aeruginosa oxyR-recG Operon in Oxidative Stress Defense and DNA Repair: OxyR-Dependent Regulation of katB-ankB, ahpB, and ahpC-ahpF

Ochsner, Urs A., Vasil, Michael L., Alsabbagh, Eyad, Parvatiyar, Kislay, Hassett, Daniel J.

Pseudomonas aeruginosa possesses an extensive armament of genes involved in oxidative stress defense, including katB-ankB, ahpB, and ahpC-ahpF. Transcription of these genes was regulated in response...

Genetic and Physiological Characterization of ohr, Encoding a Protein Involved in Organic Hydroperoxide Resistance in Pseudomonas aeruginosa

Ochsner, Urs A., Hassett, Daniel J., Vasil, Michael L.

The ohr (organic hydroperoxide resistance) gene product of Pseudomonas aeruginosa was essential for optimal resistance to organic hydroperoxides (OHPs) but not to hydrogen peroxide or paraquat. A...

Characterization of an Endoprotease (PrpL) Encoded by a PvdS-Regulated Gene in Pseudomonas aeruginosa

Wilderman, Paula J., Vasil, Adriana I., Johnson, Zaiga, Wilson, Megan J., Cunliffe, Heather E., Lamont, Iain L., ...

The expression of many virulence factors in Pseudomonas aeruginosa is dependent upon environmental conditions, including iron levels, oxygen, temperature, and osmolarity. The virulence of P....

The Fur-Regulated Gene Encoding the Alternative Sigma Factor PvdS Is Required for Iron-Dependent Expression of the LysR-Type Regulator PtxR in Pseudomonas aeruginosa

Vasil, Michael L., Ochsner, Urs A., Johnson, Zaiga, Colmer, Jane A., Hamood, Abdul N.

We previously identified a novel regulator of the exotoxin A gene (toxA) in Pseudomonas aeruginosa, PtxR, that belongs to the LysR family of prokaryotic regulatory proteins. Preliminary data also...

Protection against Exotoxin A (ETA) and Pseudomonas aeruginosa Infection in Mice with ETA-Specific Antipeptide Antibodies

El-Zaim, Haissam S., Chopra, Ashok K., Peterson, Johnny W., Vasil, Michael L., Heggers, John P.

Pseudomonas aeruginosa is an opportunistic pathogen that causes serious and sometimes fatal infections in the compromised host, especially in patients with major trauma or thermal injuries. Exotoxin...

Pseudomonas aeruginosa Hemolytic Phospholipase C Suppresses Neutrophil Respiratory Burst Activity

Terada, Lance S., Johansen, Kristine A., Nowbar, Sogol, Vasil, Adriana I., Vasil, Michael L.

Pseudomonas aeruginosa is a persistent pathogen in the airways of patients with cystic fibrosis or bronchiectasis from other causes and appears to have evolved strategies to survive the inflammatory...

Effects of the twin-arginine translocase on secretion of virulence factors, stress response, and pathogenesis

Ochsner, Urs A., Snyder, Aleksandra, Vasil, Adriana I., Vasil, Michael L.

A novel secretion pathway originally found in plants has recently been discovered in bacteria and termed TAT, for “twin-arginine translocation,” with respect to the presence of an Arg-Arg motif...

Siderophore-mediated signaling regulates virulence factor production in Pseudomonas aeruginosa

Lamont, Iain L., Beare, Paul A., Ochsner, Urs, Vasil, Adriana I., Vasil, Michael L.

Numerous bacteria secrete low molecular weight compounds termed siderophores that have a high affinity for iron ions. Siderophores have a well-documented role as iron-scavenging chemicals, chelating...

Involvement of the twin-arginine translocation system in protein secretion via the type II pathway

Voulhoux, Romé, Ball, Geneviève, Ize, Bérengère, Vasil, Michael L., Lazdunski, Andrée, Wu, Long-Fei, ...

The general secretory pathway (GSP) is a two-step process for the secretion of proteins by Gram-negative bacteria. The translocation across the outer membrane is carried out by the type II system,...

Pulmonary Inflammation Induced by Pseudomonas aeruginosa Lipopolysaccharide, Phospholipase C, and Exotoxin A: Role of Interferon Regulatory Factor 1

Wieland, Catharina W., Siegmund, Britta, Senaldi, Giorgio, Vasil, Michael L., Dinarello, Charles A., Fantuzzi, Giamila

Chronic pulmonary infection with Pseudomonas aeruginosa is common in cystic fibrosis (CF) patients. P. aeruginosa lipopolysaccharide (LPS), phosholipase C (PLC), and exotoxin A (ETA) were evaluated...

Pseudomonas aeruginosa Synthesizes Phosphatidylcholine by Use of the Phosphatidylcholine Synthase Pathway

Wilderman, Paula J., Vasil, Adriana I., Martin, Wesley E., Murphy, Robert C., Vasil, Michael L.

Phosphatidylcholine (PC) is a ubiquitous membrane lipid in eukaryotes but has been found in only a limited number of prokaryotes. Both eukaryotes and prokaryotes synthesize PC by methylating...

Cloning of a Phosphate-Regulated Hemolysin Gene (Phospholipase C) from Pseudomonas aeruginosa

Vasil, Michael L., Berka, Randy M., Gray, Gregory L., Nakai, Hiroshi

Phospholipase C (heat-labile hemolysin) of Pseudomonas aeruginosa is a phosphate (Pi)-regulated extracellular protein which may be a significant virulence factor of this organism. The gene for this...

Studies on Toxinogenesis in Vibrio cholerae II. An In Vitro Test for Enterotoxin Production

Vasil, Michael L., Holmes, Randall K., Finkelstein, Richard A.

An Elek test for enterotoxin-producing strains of Vibrio cholerae is described. Thirty-five out of 37 strains of classical V. cholerae produced positive reactions, but only 1 of 69 E1 Tor vibrio...

Identification of tandem duplicate regulatory small RNAs in Pseudomonas aeruginosa involved in iron homeostasis

Wilderman, Paula J., Sowa, Nathaniel A., FitzGerald, David J., FitzGerald, Peter C., Gottesman, Susan, Ochsner, Urs A., ...

In many bacteria, iron homeostasis is controlled primarily by the ferric uptake regulator (Fur), a transcriptional repressor. However, some genes, including those involved in iron storage, are...

Enhanced Pseudomonas aeruginosa Biofilm Development Mediated by Human Neutrophils

Walker, Travis S., Tomlin, Kerry L., Worthen, G. Scott, Poch, Katie R., Lieber, Jonathan G., Saavedra, Milene T., ...

Cystic fibrosis (CF) lung disease features persistent neutrophil accumulation to the airways from the time of infancy. CF children are frequently exposed to Pseudomonas aeruginosa, and by adulthood,...

Iron and Pseudomonas aeruginosa biofilm formation

Banin, Ehud, Vasil, Michael L., Greenberg, E. Peter

Iron serves as a signal in Pseudomonas aeruginosa biofilm development. We examined the influence of mutations in known and putative iron acquisition-signaling genes on biofilm morphology. In...

Rational Design of α-Helical Antimicrobial Peptides with Enhanced Activities and Specificity/Therapeutic Index*

Chen, Yuxin, Mant, Colin T., Farmer, Susan W., Hancock, Robert E. W., Vasil, Michael L., Hodges, Robert S.

In the present study, the 26-residue peptide sequence Ac-KWKSFLKTFKSAVKTVLHTALKAISS-amide (V681) was utilized as the framework to study the effects of peptide hydrophobicity/hydrophilicity,...

Role of the Pseudomonas aeruginosa PlcH Tat Signal Peptide in Protein Secretion, Transcription, and Cross-Species Tat Secretion System Compatibility

Snyder, Aleksandra, Vasil, Adriana I., Zajdowicz, Sheryl L., Wilson, Zachary R., Vasil, Michael L.

The secretion of PlcH and its homolog PlcN of Pseudomonas aeruginosa through the inner membrane depends upon a functional twin arginine translocase (Tat) system and a Tat signal sequence. Conserved...

Pseudomonas aeruginosa fur Overlaps with a Gene Encoding a Novel Outer Membrane Lipoprotein, OmlA

Ochsner, Urs A., Vasil, Adriana I., Johnson, Zaiga, Vasil, Michael L.

A novel outer membrane lipoprotein in Pseudomonas aeruginosa is encoded by the omlA gene, which was identified immediately upstream of the fur (ferric uptake regulator) gene. The omlA and fur genes...

Bacterioferritin A Modulates Catalase A (KatA) Activity and Resistance to Hydrogen Peroxide in Pseudomonas aeruginosa

Ma, Ju-Fang, Ochsner, Urs A., Klotz, Martin G., Nanayakkara, Vagira K., Howell, Michael L., Johnson, Zaiga, ...

We have cloned a 3.6-kb genomic DNA fragment from Pseudomonas aeruginosa harboring the rpoA, rplQ, katA, and bfrA genes. These loci are predicted to encode, respectively, (i) the α subunit of RNA...

The pvc Gene Cluster of Pseudomonas aeruginosa: Role in Synthesis of the Pyoverdine Chromophore and Regulation by PtxR and PvdS

Stintzi, Alain, Johnson, Zaiga, Stonehouse, Martin, Ochsner, Urs, Meyer, Jean-Marie, Vasil, Michael L., ...

A putative operon of four genes implicated in the synthesis of the chromophore moiety of the Pseudomonas aeruginosa siderophore pyoverdine, dubbed pvcABCD (where pvc stands for pyoverdine...

Role of the Pseudomonas aeruginosa oxyR-recG Operon in Oxidative Stress Defense and DNA Repair: OxyR-Dependent Regulation of katB-ankB, ahpB, and ahpC-ahpF

Ochsner, Urs A., Vasil, Michael L., Alsabbagh, Eyad, Parvatiyar, Kislay, Hassett, Daniel J.

Pseudomonas aeruginosa possesses an extensive armament of genes involved in oxidative stress defense, including katB-ankB, ahpB, and ahpC-ahpF. Transcription of these genes was regulated in response...

Genetic and Physiological Characterization of ohr, Encoding a Protein Involved in Organic Hydroperoxide Resistance in Pseudomonas aeruginosa

Ochsner, Urs A., Hassett, Daniel J., Vasil, Michael L.

The ohr (organic hydroperoxide resistance) gene product of Pseudomonas aeruginosa was essential for optimal resistance to organic hydroperoxides (OHPs) but not to hydrogen peroxide or paraquat. A...

Characterization of an Endoprotease (PrpL) Encoded by a PvdS-Regulated Gene in Pseudomonas aeruginosa

Wilderman, Paula J., Vasil, Adriana I., Johnson, Zaiga, Wilson, Megan J., Cunliffe, Heather E., Lamont, Iain L., ...

The expression of many virulence factors in Pseudomonas aeruginosa is dependent upon environmental conditions, including iron levels, oxygen, temperature, and osmolarity. The virulence of P....

The Fur-Regulated Gene Encoding the Alternative Sigma Factor PvdS Is Required for Iron-Dependent Expression of the LysR-Type Regulator PtxR in Pseudomonas aeruginosa

Vasil, Michael L., Ochsner, Urs A., Johnson, Zaiga, Colmer, Jane A., Hamood, Abdul N.

We previously identified a novel regulator of the exotoxin A gene (toxA) in Pseudomonas aeruginosa, PtxR, that belongs to the LysR family of prokaryotic regulatory proteins. Preliminary data also...

Protection against Exotoxin A (ETA) and Pseudomonas aeruginosa Infection in Mice with ETA-Specific Antipeptide Antibodies

El-Zaim, Haissam S., Chopra, Ashok K., Peterson, Johnny W., Vasil, Michael L., Heggers, John P.

Pseudomonas aeruginosa is an opportunistic pathogen that causes serious and sometimes fatal infections in the compromised host, especially in patients with major trauma or thermal injuries. Exotoxin...

Pseudomonas aeruginosa Hemolytic Phospholipase C Suppresses Neutrophil Respiratory Burst Activity

Terada, Lance S., Johansen, Kristine A., Nowbar, Sogol, Vasil, Adriana I., Vasil, Michael L.

Pseudomonas aeruginosa is a persistent pathogen in the airways of patients with cystic fibrosis or bronchiectasis from other causes and appears to have evolved strategies to survive the inflammatory...

Effects of the twin-arginine translocase on secretion of virulence factors, stress response, and pathogenesis

Ochsner, Urs A., Snyder, Aleksandra, Vasil, Adriana I., Vasil, Michael L.

A novel secretion pathway originally found in plants has recently been discovered in bacteria and termed TAT, for “twin-arginine translocation,” with respect to the presence of an Arg-Arg motif...

Siderophore-mediated signaling regulates virulence factor production in Pseudomonas aeruginosa

Lamont, Iain L., Beare, Paul A., Ochsner, Urs, Vasil, Adriana I., Vasil, Michael L.

Numerous bacteria secrete low molecular weight compounds termed siderophores that have a high affinity for iron ions. Siderophores have a well-documented role as iron-scavenging chemicals, chelating...

Involvement of the twin-arginine translocation system in protein secretion via the type II pathway

Voulhoux, Romé, Ball, Geneviève, Ize, Bérengère, Vasil, Michael L., Lazdunski, Andrée, Wu, Long-Fei, ...

The general secretory pathway (GSP) is a two-step process for the secretion of proteins by Gram-negative bacteria. The translocation across the outer membrane is carried out by the type II system,...

Pulmonary Inflammation Induced by Pseudomonas aeruginosa Lipopolysaccharide, Phospholipase C, and Exotoxin A: Role of Interferon Regulatory Factor 1

Wieland, Catharina W., Siegmund, Britta, Senaldi, Giorgio, Vasil, Michael L., Dinarello, Charles A., Fantuzzi, Giamila

Chronic pulmonary infection with Pseudomonas aeruginosa is common in cystic fibrosis (CF) patients. P. aeruginosa lipopolysaccharide (LPS), phosholipase C (PLC), and exotoxin A (ETA) were evaluated...

Pseudomonas aeruginosa Synthesizes Phosphatidylcholine by Use of the Phosphatidylcholine Synthase Pathway

Wilderman, Paula J., Vasil, Adriana I., Martin, Wesley E., Murphy, Robert C., Vasil, Michael L.

Phosphatidylcholine (PC) is a ubiquitous membrane lipid in eukaryotes but has been found in only a limited number of prokaryotes. Both eukaryotes and prokaryotes synthesize PC by methylating...

Cloning of a Phosphate-Regulated Hemolysin Gene (Phospholipase C) from Pseudomonas aeruginosa

Vasil, Michael L., Berka, Randy M., Gray, Gregory L., Nakai, Hiroshi

Phospholipase C (heat-labile hemolysin) of Pseudomonas aeruginosa is a phosphate (Pi)-regulated extracellular protein which may be a significant virulence factor of this organism. The gene for this...

Studies on Toxinogenesis in Vibrio cholerae II. An In Vitro Test for Enterotoxin Production

Vasil, Michael L., Holmes, Randall K., Finkelstein, Richard A.

An Elek test for enterotoxin-producing strains of Vibrio cholerae is described. Thirty-five out of 37 strains of classical V. cholerae produced positive reactions, but only 1 of 69 E1 Tor vibrio...

Identification of tandem duplicate regulatory small RNAs in Pseudomonas aeruginosa involved in iron homeostasis

Wilderman, Paula J., Sowa, Nathaniel A., FitzGerald, David J., FitzGerald, Peter C., Gottesman, Susan, Ochsner, Urs A., ...

In many bacteria, iron homeostasis is controlled primarily by the ferric uptake regulator (Fur), a transcriptional repressor. However, some genes, including those involved in iron storage, are...

Enhanced Pseudomonas aeruginosa Biofilm Development Mediated by Human Neutrophils

Walker, Travis S., Tomlin, Kerry L., Worthen, G. Scott, Poch, Katie R., Lieber, Jonathan G., Saavedra, Milene T., ...

Cystic fibrosis (CF) lung disease features persistent neutrophil accumulation to the airways from the time of infancy. CF children are frequently exposed to Pseudomonas aeruginosa, and by adulthood,...

Iron and Pseudomonas aeruginosa biofilm formation

Banin, Ehud, Vasil, Michael L., Greenberg, E. Peter

Iron serves as a signal in Pseudomonas aeruginosa biofilm development. We examined the influence of mutations in known and putative iron acquisition-signaling genes on biofilm morphology. In...

Role of the Pseudomonas aeruginosa PlcH Tat Signal Peptide in Protein Secretion, Transcription, and Cross-Species Tat Secretion System Compatibility

Snyder, Aleksandra, Vasil, Adriana I., Zajdowicz, Sheryl L., Wilson, Zachary R., Vasil, Michael L.

The secretion of PlcH and its homolog PlcN of Pseudomonas aeruginosa through the inner membrane depends upon a functional twin arginine translocase (Tat) system and a Tat signal sequence. Conserved...

Role of Peptide Hydrophobicity in the Mechanism of Action of α-Helical Antimicrobial Peptides▿

Chen, Yuxin, Guarnieri, Michael T., Vasil, Adriana I., Vasil, Michael L., Mant, Colin T., Hodges, Robert S.

In the present study, the 26-residue amphipathic α-helical antimicrobial peptide V13KL (Y. Chen et al., J. Biol. Chem. 2005, 280:12316-12329, 2005) was used as the framework to study the effects of...

Purification and Characterization of Mycobacterial Phospholipase A: an Activity Associated with Mycobacterial Cutinase▿

Parker, Sarah K., Curtin, Kathryn M., Vasil, Michael L.

We describe mycobacterial phospholipase A activity (MPLA) and, using reverse genetics, have associated this activity with putative mycobacterial cutinase. PLAs, which hydrolyze fatty acids on...

Pseudomonas aeruginosa Twitching Motility-Mediated Chemotaxis towards Phospholipids and Fatty Acids: Specificity and Metabolic Requirements▿ ‡

Miller, Rhea M., Tomaras, Andrew P., Barker, Adam P., Voelker, Dennis R., Chan, Edward D., Vasil, Adriana I., ...

Pseudomonas aeruginosa demonstrates type IV pilus-mediated directional twitching motility up a gradient of phosphatidylethanolamine (PE). Only one of four extracellular phospholipases C of P....

Mycobacterium tuberculosis Rv3802c Encodes a Phospholipase/Thioesterase and Is Inhibited by the Antimycobacterial Agent Tetrahydrolipstatin

Parker, Sarah K., Barkley, Robert M., Rino, John G., Vasil, Michael L.

The cell wall of M. tuberculosis is central to its success as a pathogen. Mycolic acids are key components of this cell wall. The genes involved in joining the α and mero mycolates are located in a...

The Metal-Dependent Regulators FurA and FurB from Mycobacterium Tuberculosis

Lucarelli, Debora, Vasil, Michael L., Meyer-Klaucke, Wolfram, Pohl, Ehmke

The ferric uptake regulators (Fur) form a large family of bacterial metal-activated DNA-binding proteins that control a diverse set of genes at the transcriptional level. Mycobacterium tuberculosis,...

A Complex Extracellular Sphingomyelinase of Pseudomonas aeruginosa Inhibits Angiogenesis by Selective Cytotoxicity to Endothelial Cells

Vasil, Michael L., Stonehouse, Martin J., Vasil, Adriana I., Wadsworth, Sandra J., Goldfine, Howard, Bolcome, Robert E., ...

The hemolytic phospholipase C (PlcHR) expressed by Pseudomonas aeruginosa is the original member of a Phosphoesterase Superfamily, which includes phosphorylcholine-specific phospholipases C (PC-PLC)...

The Influence of Iron on Pseudomonas aeruginosa Physiology: A REGULATORY LINK BETWEEN IRON AND QUORUM SENSING*S⃞

Oglesby, Amanda G., Farrow, John M., Lee, Joon-Hee, Tomaras, Andrew P., Greenberg, E. P., Pesci, Everett C., ...

In iron-replete environments, the Pseudomonas aeruginosa Fur (ferric uptake regulator) protein represses expression of two small regulatory RNAs encoded by prrF1 and prrF2. Here we describe the...