scholarly journals Characterization of a Novel Gene, wosA, Regulating FlhDC Expression in Proteus mirabilis

2008 ◽  
Vol 190 (6) ◽  
pp. 1946-1955 ◽  
Author(s):  
Janet K. Hatt ◽  
Philip N. Rather
Keyword(s):  
Cell Differentiation ◽  
Liquid Medium ◽  
Proteus Mirabilis ◽  
Solid Surfaces ◽  
Swarming Motility ◽  
Swarmer Cell ◽  
Fourfold Increase ◽  
Nonpermissive Condition

ABSTRACT In this study, we describe wosA, a Proteus mirabilis gene identified by its ability to increase swarming motility when overexpressed. At various times during the swarming cycle, the increased expression of wosA resulted in a 4- to 16-fold upregulation of the transcription of flhDC, encoding the master regulator of the flagellar cascade. In turn, the expression of flaA, encoding flagellin, was substantially increased in wosA-overexpressing strains. The overexpression of wosA also resulted in constitutive swarmer cell differentiation in liquid medium, a normally nonpermissive condition. However, in wosA-overexpressing strains, the onset of swarming was not altered. A null wosA allele resulted in a slight decrease in swarming motility. The expression of wosA was growth phase dependent during growth in liquid and on agar plates during swarmer cell differentiation. Increasing the viscosity of liquid medium by the addition of polyvinylpyrrolidone induced swarmer cell differentiation and resulted in a fourfold increase in wosA transcription. A fliL mutation that results in constitutive swarmer cell elongation also increased wosA transcription. In this study, we discuss the possible role of the wosA gene product in signal transduction from solid surfaces to induce swarmer cell differentiation, possibly via alterations in the motor switch complex. This study also suggests that despite constitutive swarmer cell differentiation in wosA-overexpressing strains, there are additional regulatory and/or environmental conditions that may control the onset of swarming migration.

scholarly journals Regulation of the Min Cell Division Inhibition Complex by the Rcs Phosphorelay in Proteus mirabilis

2015 ◽  
Vol 197 (15) ◽  
pp. 2499-2507 ◽  
Author(s):  
Kristen E. Howery ◽  
Katy M. Clemmer ◽  
Emrah Şimşek ◽  
Minsu Kim ◽  
Philip N. Rather
Keyword(s):  
Cell Division ◽  
Cell Differentiation ◽  
Proteus Mirabilis ◽  
Cell Elongation ◽  
Response Regulator ◽  
Swarmer Cell ◽  
Content Type ◽  
Expression Of Genes ◽  
Rapid Amplification

ABSTRACTA key regulator of swarming inProteus mirabilisis the Rcs phosphorelay, which repressesflhDC, encoding the master flagellar regulator FlhD4C2. Mutants inrcsB, the response regulator in the Rcs phosphorelay, hyperswarm on solid agar and differentiate into swarmer cells in liquid, demonstrating that this system also influences the expression of genes central to differentiation. To gain a further understanding of RcsB-regulated genes involved in swarmer cell differentiation, transcriptome sequencing (RNA-Seq) was used to examine the RcsB regulon. Among the 133 genes identified,minCandminD, encoding cell division inhibitors, were identified as RcsB-activated genes. A third gene,minE, was shown to be part of an operon withminCD. To examineminCDEregulation, theminpromoter was identified by 5′ rapid amplification of cDNA ends (5′-RACE), and both transcriptionallacZfusions and quantitative real-time reverse transcriptase (qRT) PCR were used to confirm that theminCDEoperon was RcsB activated. Purified RcsB was capable of directly binding theminCpromoter region. To determine the role of RcsB-mediated activation ofminCDEin swarmer cell differentiation, a polarminCmutation was constructed. This mutant formed minicells during growth in liquid, produced shortened swarmer cells during differentiation, and exhibited decreased swarming motility.IMPORTANCEThis work describes the regulation and role of the MinCDE cell division system inP. mirabilisswarming and swarmer cell elongation. Prior to this study, the mechanisms that inhibit cell division and allow swarmer cell elongation were unknown. In addition, this work outlines for the first time the RcsB regulon inP. mirabilis. Taken together, the data presented in this study begin to address howP. mirabiliselongates upon contact with a solid surface.

scholarly journals Ultrastructure of Proteus mirabilis Swarmer Cell Rafts and Role of Swarming in Catheter-Associated Urinary Tract Infection

2004 ◽  
Vol 72 (7) ◽  
pp. 3941-3950 ◽  
Author(s):  
Brian V. Jones ◽  
Robert Young ◽  
Eshwar Mahenthiralingam ◽  
David J. Stickler
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Proteus Mirabilis ◽  
Solid Surfaces ◽  
Urethral Meatus ◽  
Fixation Technique ◽  
Swarmer Cell ◽  
Transposon Mutants

ABSTRACT Proteus mirabilis is a common cause of catheter-associated urinary tract infection (C-UTI). It blocks indwelling urethral catheters through the formation of extensive crystalline biofilms. The obstruction of urine flow can induce episodes of pyelonephritis, septicemia, and shock. P. mirabilis exhibits a type of motility referred to as swarming, in which multicellular rafts of elongated, hyperflagellated swarmer cells form and move rapidly in concert over solid surfaces. It has been suggested that swarming is important in the pathogenesis of C-UTI. In this study we generated a set of stable transposon mutants deficient in swarming and used them to assess the role of swarming in the migration of P. mirabilis over urinary catheters. Swarming was found to be essential for migration over all-silicone catheters. Swarming-deficient mutants were attenuated in migration over hydrogel-coated latex catheters, but those capable of swimming motility were able to move over and infect these surfaces. A novel vapor fixation technique for the preparation of specimens and scanning electron microscopy were used to resolve the ultrastructure of P. mirabilis multicellular rafts. The flagellar filaments of P. mirabilis were found to be highly organized during raft migration and were interwoven in phase to form helical connections between adjacent swarmer cells. Mutants lacking these novel organized structures failed to swarm successfully. We suggest that these structures are important for migration and formation of multicellular rafts. In addition, the highly organized structure of multicellular rafts enables P. mirabilis to initiate C-UTI by migration over catheter surfaces from the urethral meatus into the bladder.

scholarly journals Loss of the WaaL O-Antigen Ligase Prevents Surface Activation of the Flagellar Gene Cascade in Proteus mirabilis

2010 ◽  
Vol 192 (12) ◽  
pp. 3213-3221 ◽  
Author(s):  
Randy M. Morgenstein ◽  
Katy M. Clemmer ◽  
Philip N. Rather
Keyword(s):  
Proteus Mirabilis ◽  
Lipid A ◽  
Response Regulator ◽  
Soft Agar ◽  
Solid Surfaces ◽  
Loss Of Function ◽  
Swarmer Cell ◽  
Gram Negative ◽  
O Antigen ◽  
Enterobacterial Common Antigen

ABSTRACT Proteus mirabilis is a Gram-negative bacterium that undergoes a physical and biochemical change from a vegetative swimmer cell (a typical Gram-negative rod) to an elongated swarmer cell when grown on a solid surface. In this study, we report that a transposon insertion in the waaL gene, encoding O-antigen ligase, blocked swarming motility on solid surfaces but had little effect on swimming motility in soft agar. The waaL mutant was unable to differentiate into a swarmer cell. Differentiation was also prevented by a mutation in wzz, encoding a chain length determinant for O antigen, but not by a mutation in wzyE, encoding an enzyme that polymerizes enterobacterial common antigen, a surface polysaccharide different from the lipid A::core. In wild-type P. mirabilis, increased expression of the flhDC operon occurs after growth on solid surfaces and is required for the high-level expression of flagellin that is characteristic of swarmer cells. However, in both the waaL and the wzz mutants, the flhDC operon was not activated during growth on agar. A loss-of-function mutation in the rcsB response regulator or overexpression of flhDC restored swarming to the waaL mutant, despite the absence of O antigen. Therefore, although O antigen may serve a role in swarming by promoting wettability, the loss of O antigen blocks a regulatory pathway that links surface contact with the upregulation of flhDC expression.

scholarly journals Genetics of Swarming Motility in Salmonella enterica Serovar Typhimurium: Critical Role for Lipopolysaccharide

2000 ◽  
Vol 182 (22) ◽  
pp. 6308-6321 ◽  
Author(s):  
Adam Toguchi ◽  
Michael Siano ◽  
Mark Burkart ◽  
Rasika M. Harshey
Keyword(s):  
Cell Differentiation ◽  
Salmonella Enterica ◽  
Critical Role ◽  
Growth Surface ◽  
Iron Starvation ◽  
Swarming Motility ◽  
Swarmer Cell ◽  
Two Component ◽  
Serovar Typhimurium ◽  
Two Component Systems

ABSTRACT Salmonella enterica serovar Typhimurium can differentiate into hyperflagellated swarmer cells on agar of an appropriate consistency (0.5 to 0.8%), allowing efficient colonization of the growth surface. Flagella are essential for this form of motility. In order to identify genes involved in swarming, we carried out extensive transposon mutagenesis of serovar Typhimurium, screening for those that had functional flagella yet were unable to swarm. A majority of these mutants were defective in lipopolysaccharide (LPS) synthesis, a large number were defective in chemotaxis, and some had defects in putative two-component signaling components. While the latter two classes were defective in swarmer cell differentiation, representative LPS mutants were not and could be rescued for swarming by external addition of a biosurfactant. A mutation in waaG(LPS core modification) secreted copious amounts of slime and showed a precocious swarming phenotype. We suggest that the O antigen improves surface “wettability” required for swarm colony expansion, that the LPS core could play a role in slime generation, and that multiple two-component systems cooperate to promote swarmer cell differentiation. The failure to identify specific swarming signals such as amino acids, pH changes, oxygen, iron starvation, increased viscosity, flagellar rotation, or autoinducers leads us to consider a model in which the external slime is itself both the signal and the milieu for swarming motility. The model explains the cell density dependence of the swarming phenomenon.

scholarly journals A Novel Gene Involved in Regulating the Flagellar Gene Cascade in Proteus mirabilis

2006 ◽  
Vol 188 (22) ◽  
pp. 7830-7839 ◽  
Author(s):  
Lindsay G. Stevenson ◽  
Philip N. Rather
Keyword(s):  
Cell Differentiation ◽  
Amino Acid ◽  
Proteus Mirabilis ◽  
Fold Increase ◽  
Single Copy ◽  
Flagellar Gene ◽  
Mrna Accumulation ◽  
Swarmer Cell ◽  
Novel Gene ◽  
Expression Of Genes

ABSTRACT In this study, we identified a transposon insertion in a novel gene, designated disA, that restored swarming motility to a putrescine-deficient speA mutant of Proteus mirabilis. A null allele in disA also increased swarming in a wild-type background. The DisA gene product was homologous to amino acid decarboxylases, and its role in regulating swarming was investigated by examining the expression of genes in the flagellar cascade. In a disA mutant background, we observed a 1.4-fold increase in the expression of flhDC, which encodes FlhD2C2, the master regulator of the flagellar gene cascade. However, the expressions of class 2 (fliA, flgM) and class 3 (flaA) genes were at least 16-fold higher in the disA background during swarmer cell differentiation. Overexpression of DisA on a high-copy-number plasmid did not significantly decrease flhDC mRNA accumulation but resulted in a complete block in mRNA accumulation for both fliA and flaA. DisA overexpression also blocked swarmer cell differentiation. The disA gene was regulated during the swarming cycle, and a single-copy disA::lacZ fusion exhibited a threefold increase in expression in swarmer cells. Given that DisA was similar to amino acid decarboxylases, a panel of decarboxylated amino acids was tested for effects similar to DisA overexpression, and phenethylamine, the product of phenylalanine decarboxylation, was capable of inhibiting both swarming and the expression of class 2 and class 3 genes in the flagellar regulon. A DisA-dependent decarboxylated amino acid may inhibit the formation of active FlhD2C2 heterotetramers or inhibit FlhD2C2 binding to DNA.

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