Journal ArticleDOI
Co‐ordinate expression of virulence genes during swarm‐cell differentiation and population migration of Proteus mirabilis
TLDR
Modulation of virulence factor activity during the swarming cycle resulted from differential expression of virulent genes in parallel with fliC gene expression, suggesting that differential virulence gene expression may be a specific strategy.Abstract:
The uropathogenic Gram-negative bacterium Proteus mirabilis exhibits a form of multicellular behaviour termed swarming, which involves cyclical differentiation of typical vegetative cells into filamentous, multinucleate, hyperflagellate swarm cells capable of rapid and co-ordinated population migration across surfaces. We observed that differentiation into swarm cells was accompanied by substantial increases in the activities of intracellular urease and extracellular haemolysin and metalloprotease, which are believed to be central to the pathogenicity of P. mirabilis. In addition, the ability of P. mirabilis to invade human urothelial cells in vitro was primarily a characteristic of differentiated swarm cells, not vegetative cells. These virulence factor activities fell back as the cells underwent cyclical reversion to the vegetative form (consolidation), in parallel with the diagnostic modulation of flagellin levels on the cell surface. Control cellular alkaline phosphatase activities did not increase during differentiation or consolidation. Non-flagellated, nonmotile transposon insertion mutants were unable to invade urothelial cells and they generated only low-level activities of haemolysin, urease and protease (0-10% of wild type). Motile mutants unable to differentiate into swarm cells were comparably reduced in their haemolytic, ureolytic and invasive phenotypes and generated threefold less protease activity. Mutants that were able to form swarm cells but exhibited various aberrant patterns of swarming migration produced wild-type activities of haemolysin, urease and protease, but their ability to enter urothelial cells was three- to 10-fold lower.(ABSTRACT TRUNCATED AT 250 WORDS)read more
Citations
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Journal ArticleDOI
Molecular biology of microbial ureases.
TL;DR: The crystal structure of the K. aerogenes enzyme has been determined and provides important insight into the mechanism of catalysis, and accessory genes have been shown to be required for activation of urease apoprotein, and roles for the accessory proteins in metallocenter assembly have been proposed.
Journal ArticleDOI
A field guide to bacterial swarming motility
TL;DR: The requirements that define swarming motility in diverse bacterial model systems are reviewed, including an increase in the number of flagella per cell, the secretion of a surfactant to reduce surface tension and allow spreading, and movement in multicellular groups rather than as individuals.
Journal ArticleDOI
The Selective Value of Bacterial Shape
TL;DR: The aim of this review is to spell out the physical, environmental, and biological forces that favor different bacterial morphologies and which, therefore, contribute to natural selection.
Journal ArticleDOI
Complicated Catheter-Associated Urinary Tract Infections Due to Escherichia coli and Proteus mirabilis
TL;DR: Research focusing on the pathogenesis of CAUTIs will lead to a better understanding of the disease process and will subsequently lead to the development of new diagnosis, prevention, and treatment options.
Journal ArticleDOI
Escherichia coli swim on the right-hand side
Willow R. DiLuzio,Linda Turner,Michael Mayer,Piotr Garstecki,Douglas B. Weibel,Howard C. Berg,George M. Whitesides +6 more
TL;DR: It is proposed that when cells are confined between two interfaces—one an agar gel and the second PDMS—they swim closer to the agar surface than to the PDMS surface, leading to the preferential movement on the right of the microchannel, and the choice of materials guides the motion of cells in microchannels.
References
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Journal ArticleDOI
Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4
TL;DR: Using an improved method of gel electrophoresis, many hitherto unknown proteins have been found in bacteriophage T4 and some of these have been identified with specific gene products.
Journal Article
Cleavage of structural proteins during the assemble of the head of bacterio-phage T4
TL;DR: Using an improved method of gel electrophoresis, many hitherto unknown proteins have been found in bacteriophage T4 and some of these have been identified with specific gene products as mentioned in this paper.
Journal ArticleDOI
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TL;DR: Urease is a high-molecular-weight, multimeric, nickel-containing enzyme that plays an important role in utilization of environmental nitrogenous compounds and urea-based fertilizers.
Journal ArticleDOI
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Journal ArticleDOI
Environmental signals controlling expression of virulence determinants in bacteria.
TL;DR: This minireview will discuss emerging themes that characterize these virulence regulatory systems and speculate on how these control strategies might contribute to the overall success of the microbe during pathogenesis.