Intermediate filament-like proteins in bacteria and a cytoskeletal function in Streptomyces.

Actin and tubulin cytoskeletons are conserved and widespread in bacteria. A strikingly intermediate filament (IF)-like cytoskeleton, composed of crescentin, is also present in Caulobacter crescentus and determines its specific cell shape. However, the broader significance of this finding remained obscure, because crescentin appeared to be unique to Caulobacter.

Roles of curli, cellulose and BapA in Salmonella biofilm morphology studied by atomic force microscopy.

Background: Curli, cellulose and the cell surface protein BapA are matrix components in Salmonella biofilms. In this study we have investigated the roles of these components for the morphology of bacteria grown as colonies on agar plates and within a biofilm on submerged mica surfaces by applying atomic force microscopy (AFM) and light microscopy.

Results: AFM imaging was performed on colonies of Salmonella Typhimurium grown on agar plates for 24 h and on biofilms grown for 4, 8, 16 or 24 h on mica slides submerged in standing cultures.

Identification of YhdA as a regulator of the Escherichia coli carbon storage regulation system.

The Escherichia coli BarA-UvrY two-component system, which controls adaptation via the CsrB and CsrC sRNAs, is induced at the entry of the stationary phase by an unknown stimulus. Using a csrB-lacZ fusion, we demonstrated that the factors RelA, SpoT and LuxS, previously suggested to act on orthologues of this system, have no role in BarA-UvrY induction. However, using a transposon screen, we identified the hypothetical protein YhdA as a new regulator of CsrB and CsrC expression.

The Escherichia coli BarA-UvrY two-component system is a virulence determinant in the urinary tract.

Background: The Salmonella enterica BarA-SirA, the Erwinia carotovora ExpS-ExpA, the Vibrio cholerae BarA-VarA and the Pseudomonas spp GacS-GacA all belong to the same orthologous family of two-component systems as the Escherichia coli BarA-UvrY. In the first four species it has been demonstrated that disruption of this two-component system leads to a clear reduction in virulence of the bacteria. Our aim was to determine if the Escherichia coli BarA-UvrY two-component system is connected with virulence using a monkey cystitis model.

Genetic and functional characterization of the Escherichia coli BarA-UvrY two-component system: point mutations in the HAMP linker of the BarA sensor give a dominant-negative phenotype.

The BarA-UvrY two-component system family is strongly associated with virulence but is poorly understood at the molecular level. During our attempts to complement a barA deletion mutant, we consistently generated various mutated BarA proteins. We reasoned that characterization of the mutants would help us to better understand the signal transduction mechanism in tripartite sensors.

Molecular characterization of the acid-inducible asr gene of Escherichia coli and its role in acid stress response.

Enterobacteria have developed numerous constitutive and inducible strategies to sense and adapt to an external acidity. These molecular responses require dozens of specific acid shock proteins (ASPs), as shown by genomic and proteomic analysis. Most of the ASPs remain poorly characterized, and their role in the acid response and survival is unknown.

The Escherichia coli BarA-UvrY two-component system is needed for efficient switching between glycolytic and gluconeogenic carbon sources.

The Escherichia coli BarA and UvrY proteins were recently demonstrated to constitute a novel two-component system, although its function has remained largely elusive. Here we show that mutations in the sensor kinase gene, barA, or the response regulator gene, uvrY, in uropathogenic E. coli drastically affect survival in long-term competition cultures.