A novel sequence of 2.9 kb in the intergenic region between the mutS and rpoS genes of Escherichia coli O157:H7 and closely related strains replaces a sequence of 6.1 kb in E. coli K-12 strains. At the same locus in Shigella dysenteriae type 1, a sequence identical to that in O157:H7 is bounded by the IS1 insertion sequence element. Extensive polymorphism in the mutS-rpoS chromosomal region is ...

rpoS, a gene that encodes an alternative sigma factor (also known as katF), is critical for the ability of Yersinia enterocolitica grown at 37 degrees C, but not at 26 degrees C, to survive diverse environmental insults such as high temperature, hydrogen peroxide, osmolarity, and low pH. However, a Y. enterocolitica rpoS mutant was not affected in expression of inv or ail, invasion of tissue cu...

Gene expression profiles of the biological control strain Pseudomonas protegens Pf-5 inhabiting pea seed surfaces were revealed using a whole-genome oligonucleotide microarray. We identified genes expressed by Pf-5 under the control of two global regulators (GacA and RpoS) known to influence biological control and secondary metabolism. Transcript levels of 897 genes, including many with unknown...

The 102 aa Hfq protein of Escherichia coli (Hfq(Ec)) was first described as a host factor required for phage Qbeta replication. More recently, Hfq was shown to affect the stability of several E. coli mRNAs, including ompA mRNA, where it interferes with ribosome binding, which in turn results in rapid degradation of the transcript. In contrast, Hfq is also required for efficient translation of t...

The plant-pathogenic bacterium Erwinia carotovora subsp. carotovora causes plant disease mainly through a number of extracellular plant-cell-wall-degrading enzymes. In this study, the ability of an rpoS mutant of the Er. carotovora subsp. carotovora strain SCC3193 to infect plants and withstand environmental stress was characterized. This mutant was found to be sensitive to osmotic and oxidativ...

As an obligate pathogen, the Lyme disease spirochete Borrelia burgdorferi has a streamlined genome that encodes only two two-component signal transduction systems, Hk1-Rrp1 and Hk2-Rrp2 (in addition to CheA-CheY systems). The output of Hk1-Rrp1 is the production of the second messenger cyclic di-GMP (c-di-GMP), which is indispensable for B. burgdorferi to survive in the tick vector. The output ...

It has been demonstrated recently that cells of Borrelia burgdorferi sensu lato, the etiological agent of Lyme disease, transform from mobile spirochetes into nonmotile cystic forms in the presence of certain unfavourable conditions, and that cystic forms are able to reconvert to vegetative spirochetes in vitro and in vivo. The purpose of this study was to investigate the kinetics of conversion...

Numerous Salmonella enterica food-borne illness outbreaks have been associated with contaminated vegetables, in particular sprouted seeds, and the incidence of reported contamination has steadily risen. In order to understand the physiology of S. enterica serovar Newport on plants, a screen was developed to identify transposon mutants that were defective in attachment to alfalfa sprouts. Twenty...

Acetate and formate are major fermentation products of Escherichia coli. Below pH 7, the balance shifts to lactate; an oversupply of acetate or formate retards growth. E. coli W3110 was grown with aeration in potassium-modified Luria broth buffered at pH 6.7 in the presence or absence of added acetate or formate, and the protein profiles were compared by two-dimensional sodium dodecyl sulfate-p...

The general stress sigma factor sigma(S) (RpoS) in Escherichia coli is controlled at the levels of transcription, translation, and proteolysis. Here we demonstrate that the phosphorylated response regulator ArcA is a direct repressor of rpoS transcription that binds to two sites flanking the major rpoS promoter, with the upstream site overlapping an activating cAMP-CRP-binding site. The histidi...