Transposon mutagenesis in Proteus mirabilis

Belas, Robert; Erskine, Deborah; Flaherty, David K.

doi:10.1128/jb.173.19.6289-6293.1991

Cited by 114 publications

(115 citation statements)

References 13 publications

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“…BB2000 grown on agar was used as a control and typically showed >80% swarmer cells at 40-,um average length under inducing conditions. As shown in Table 2, Elo-mutants accounted for 10% (7 (Fig. 2C).…”

Section: Resultsmentioning

confidence: 99%

Proteus mirabilis mutants defective in swarmer cell differentiation and multicellular behavior

1991

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Proteus mirabilis is a dimorphic bacterium which exists in liquid cultures as a 1.5-to 2.0-,um motile swimmer cell possessing 6 to 10 peritrichous flagella. When swimmer cells are placed on a surface, they differentiate by a combination of events that ultimately produce a swarmer cell. Unlike the swimmer cell, the polyploid swarmer cell is 60 to 80 ,um long and possesses hundreds to thousands of surface-induced flagella. These features, combined with multicellular behavior, allow the swarmer cells to move over a surface in a process called swarming. Transposon TnS was used to produce P. mirabUis mutants defective in wild-type swarming motility. Two general classes of mutants were found to be defective in swarming. The first class was composed of null mutants that were completely devoid of swarming motility. The majority of nonswarming mutations were the result of defects in the synthesis of flagella or in the ability to rotate the flagella. The remaining nonswarming mutants produced flagella but were defective in surface-induced elongation. Strains in the second general class of mutants, which made up more than 65% of all defects in swarming were motile but were defective in the control and coordination of multicellular swarming. Analysis of consolidation zones produced by such crippled mutants suggested that this pleiotropic phenotype was caused by a defect in the regulation of multicellular behavior. A possible mechanism controlling the cyclic process of differentiation and dedifferentiation involved in the swarming behavior of P. mirabilis is discussed.Proteus mirabilis is a motile gram-negative bacterium, similar in many aspects of its physiology to other members of the family Enterobacteriaceae, such as Escherichia coli and Salmonella typhimurium. It was originally described and named by Hauser in 1885 for the character in Homer's Odyssey who "has the power of assuming different shapes in order to escape being questioned" (quoted from reference 18). P. mirabilis is considered to be an opportunistic pathogen and is one of the principal causes of urinary infections in hospital patients with urinary catheters (32,34). Its ability to colonize the surfaces of catheters and the urinary tract may be aided by the characteristic first described more than a century ago and currently referred to as swarmer cell differentiation.When grown in suitable liquid media, P. mirabilis exists as 1.5-to 2.0-,um motile cells with 6 to 10 peritrichous flagella. These bacteria, called swimmer cells, display characteristic swimming and chemotactic behavior, moving toward nutrients and away from repellents (36). However, a dramatic change in cell morphology takes place when cells grown in liquid are transferred to a nutrient medium solidified with agar.

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Section: Resultsmentioning

confidence: 99%

Proteus mirabilis mutants defective in swarmer cell differentiation and multicellular behavior

1991

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“…These strains have been labelled PRM1 through PRM84. PRM1 is the parental strain of the mutants described by Belas and colleagues (4,5). After introduction of antibiotic resistance plasmids into PRM1 and PRM2, we found that about half of the transconjugants displayed new colony phenotypes characterized by narrower terraces.…”

Section: Methodsmentioning

confidence: 99%

“…Others have begun to demonstrate the genetic potential of using P. mirabilis as a morphogenetic model system (1,4,5).…”

Section: Discussionmentioning

confidence: 99%

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Periodic phenomena in Proteus mirabilis swarm colony development

et al. 1996

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Proteus mirabilis colonies exhibit striking geometric regularity. Basic microbiological methods and imaging techniques were used to measure periodic macroscopic events in swarm colony morphogenesis. We distinguished three initial phases (lag phase, first swarming phase, and first consolidation phase) followed by repeating cycles of subsequent swarming plus consolidation phases. Each Proteus swarm colony terrace corresponds to one swarming-plus-consolidation cycle. The duration of the lag phase was dependent upon inoculation density in a way that indicated the operation of both cooperative and inhibitory multicellular effects. On our standard medium, the second and subsequent swarm phases displayed structure in the form of internal waves visible with reflected and dark-field illumination. These internal waves resulted from organization of the migrating bacteria into successively thicker cohorts of swarmer cells. Bacterial growth and motility were independently modified by altering the composition of the growth medium. By varying the glucose concentration in the substrate, it was possible to alter biomass production without greatly affecting the kinetics of colony surface area expansion. By varying the agar concentration in the substrate, initial bacterial biomass production was unaffected but colony expansion dynamics were significantly altered. Higher agar concentrations led to slower, shorter swarm phases and longer consolidation phases. Thus, colony growth was restricted by higher agar concentrations but the overall timing of the swarming-plus-consolidation cycles remained constant. None of a variety of factors which had significant effects on colony expansion altered terracing frequencies at 32؇C, but the length of the swarming-plus-consolidation cycle was affected by temperature and medium enrichment. Some clinical isolates displayed significant differences in terracing frequencies at 32؇C. Our results defined a number of readily quantifiable parameters in swarm colony development. The data showed no connection between nutrient (glucose) depletion and the onset of different phases in swarm colony morphogenesis. Several observations point to the operation of density-dependent thresholds in controlling the transitions between distinct phases.Proteus mirabilis colonies have fascinated microbiologists for over a century (13). On typical laboratory media, mature P. mirabilis swarm colonies display striking patterns characterized by circular symmetry and regularly spaced concentric terraces or zones (Fig. 1) (6). These terraces develop as a result of periodic events during colony growth, most notably the cyclic repetition of alternating phases: swarming (active migration) and consolidation (growth without movement of the colony perimeter) (2, 3). Colony expansion is a dynamic process involving movement over the solid substrate by multicellular rafts of specially differentiated swarmer cells (7,18,30,32). The swarmer cells are elongated and hyperflagellated but have the same DNA/length ratio as the shorter oligofla...

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“…Plasmid pRS110 was digested with SacI and KpnI, and a 2n5 kb fragment containing luxSh ::aphA ::hluxS was ligated to pGP704 (Miller & Mekalanos, 1988) also digested with SacI and KpnI, resulting in pRS112. This plasmid was transformed into E. coli SM10 λpir and conjugally transferred to P. mirabilis BB2000 by filter mating (Belas et al, 1991a). Mutation of the chromosomal copy of luxS PM was confirmed by antibiotic resistance spectrum (Km R Ap S ), PCR amplification of luxS PM locus from the putative luxS strain, and measurement of AI-2 activity using the V. harveyi luminescence assay.…”

Section: Methodsmentioning

confidence: 99%

Detection and mutation of a luxS-encoded autoinducer in Proteus mirabilis The GenBank accession number for the sequence reported in this paper is AY044337.

et al. 2002

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Quorum sensing regulates the expression of virulence factors in a wide variety of pathogenic bacteria. This study has shown that Proteus mirabilis harbours a homologue of luxS, a gene required for the synthesis of the quorum sensing autoinducer 2 (AI-2). AI-2 activity is expressed during and is correlated with the initiation of swarming migration on agar surfaces. The P. mirabilis luxS locus was cloned and a LuxS N strain constructed by allelic-exchange mutagenesis. While lacking AI-2 activity, a null mutation in luxS, however, did not affect swimming or swarming motility, swarmer cell differentiation, or virulence in a mouse model of ascending urinary tract infection.

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Transposon mutagenesis in Proteus mirabilis

Cited by 114 publications

References 13 publications

Proteus mirabilis mutants defective in swarmer cell differentiation and multicellular behavior

Proteus mirabilis mutants defective in swarmer cell differentiation and multicellular behavior

Periodic phenomena in Proteus mirabilis swarm colony development

Detection and mutation of a luxS-encoded autoinducer in Proteus mirabilis The GenBank accession number for the sequence reported in this paper is AY044337.

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