Gene Conservation and Loss in the
            <i>mutS-rpoS</i>
            Genomic Region of Pathogenic
            <i>Escherichia coli</i>

Herbelin, C.; Chirillo, Samantha C.; Melnick, Kristen A.; Whittam, Thomas S.

doi:10.1128/jb.182.19.5381-5390.2000

Cited by 46 publications

(46 citation statements)

References 38 publications

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“…Consistent Recent studies revealed a pathotype-associated polymorphism in the mutS-rpoS region of the E. coli chromosome (14,21,39). PCR analysis showed that 29% of the afa-8 isolates differed from E. coli K-12 in the mutS-rpoS intergenic region.…”

Section: Discussionmentioning

confidence: 82%

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Extended Virulence Genotype of Pathogenic Escherichia coli Isolates Carrying the afa-8 Operon: Evidence of Similarities between Isolates from Humans and Animals with Extraintestinal Infections

et al. 2003

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The afimbrial AfaE-VIII adhesin is common among Escherichia coli isolates from calves with intestinal and/or extraintestinal infections and from humans with sepsis or pyelonephritis. The virulence genotypes of 77 Escherichia coli afa-8 isolates from farm animals and humans were compared to determine whether any trait of commonality exists between isolates of the different host species. Over half of the extraintestinal afa-8 isolates were associated with pap and f17Ac adhesin genes and contained virulence genes (pap, hly, and cnf1) which are characteristic of human extraintestinal pathogenic E. coli (ExPEC). PapG, which occurs as three known variants (variants I to III), is encoded by the corresponding three alleles of papG. Among the pappositive strains, new papG variants (papGrs) that differed from the isolates with genes for the three adhesin classes predominated over isolates with papG allele III, which in turn were more prevalent than those with allele II. The data showed the substantial prevalence of the enteroaggregative E. coli heat-stable enterotoxin gene ( The fimbrial and afimbrial adhesins of the Afa family mediate the adherence of uropathogenic and diarrhea-associated Escherichia coli to various host tissues. Among the Afa-related surface antigens, the Afa(Dr ϩ ) adhesins (AfaE-I, AfaE-III, Dr, and F1845) bind to epithelial cells via recognition of the decay-accelerating factor (DAF; also referred to as CD55) carrying the Dr blood group antigen (15,33,36,37,44). We recently described a new afa operon (afa-8) encoding afimbrial adhesin AfaE-VIII which does not recognize DAF molecules (Afa(Dr Ϫ ) adhesin). The afa-8 operon can be either chromosome or plasmid borne, suggesting that it may be carried by a mobile element, facilitating its dissemination (16, 34). It therefore appears that in some strains the afa-8 operon is carried by a 61-kb pathogenicity island (PAI) inserted into pheV and/or pheR tRNA-encoding genes. Partial characterization of the afa-8-containing PAI indicated that this PAI carries the afa-8 operon as the only known virulence determinant (35).The afa-8 operon is common among pathogenic E. coli strains isolated from animals and humans (16,34,52). It was frequently found in animal and human isolates producing CNF toxins, but it has also been detected in CNF-negative strains isolated from calves and piglets (16,41). Bloodstream infections in which the bacteria are derived from the intestinal flora by bacterial translocation are common in patients with cancer. Preliminary results showed that the afa-8 operon is found in CNF1-producing strains associated with this type of bacteremia (22,38,42). Therefore, afa-8 is probably involved in the development of extraintestinal infections associated with primary colonization of the intestine. However, afa-8 has never been detected in diarrhea-associated human isolates (38). In addition to CNF1, certain afa-8-positive strains carry virulence factor (VF) genes including pap, sfa, f17A, and clpG (P, S, F17, and CS31A adhesins, respectively) and hlyA (...

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Section: Discussionmentioning

confidence: 82%

“…In comparison to E. coli MG1655, previous studies (14,21,39) revealed that EPEC, EHEC, and E. coli group B2 strains harbor specific DNA insertions within the mutS-rpoS intergenic region. A PCR assay was developed to determine the nature of the mutS-rpoS intergenic region of the afa-8 isolates.…”

Section: Methodsmentioning

confidence: 99%

Extended Virulence Genotype of Pathogenic Escherichia coli Isolates Carrying the afa-8 Operon: Evidence of Similarities between Isolates from Humans and Animals with Extraintestinal Infections

et al. 2003

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“…If the mutations in the populations measured in Figure 7 are due to mutations in other parts of the pathway, then this elevated mutation rate cannot be attributed to mutation at the rpoS locus alone. However, the mutS-rpoS intergenic region has been demonstrated to be variable in enteric bacteria (Herbelin et al, 2000;Kotewicz et al, 2002Kotewicz et al, , 2003, which suggests a history of duplications and deletions in this region. This suggests that this elevated mutation rate may apply primarily at the rpoS locus.…”

Section: Discussionmentioning

confidence: 99%

Evolutionary loss of the rdar morphotype in Salmonella as a result of high mutation rates during laboratory passage

2008

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Rapid evolution of microbes under laboratory conditions can lead to domestication of environmental or clinical strains. In this work, we show that domestication due to laboratory passage in rich medium is extremely rapid. Passaging of wild-type Salmonella in rich medium led to diversification of genotypes contributing to the loss of a spatial phenotype, called the rdar morphotype, within days. Gene expression analysis of the rdar regulatory network demonstrated that mutations were primarily within rpoS, indicating that the selection pressure for scavenging during stationary phase had the secondary effect of impairing this highly conserved phenotype. If stationary phase was omitted from the experiment, radiation of genotypes and loss of the rdar morphotype was also demonstrated, but due to mutations within the cellulose biosynthesis pathway and also in an unknown upstream regulator. Thus regardless of the selection pressure, rapid regulatory changes can be observed on laboratory timescales. The speed of accumulation of rpoS mutations during daily passaging could not be explained by measured fitness and mutation rates. A model of mutation accumulation suggests that to generate the observed accumulation of r 38 mutations, this locus must experience a mutation rate of approximately 10 À4 mutations/gene/generation. Sequencing and gene expression of population isolates indicated that there were a wide variety of r 38 phenotypes within each population. This suggests that the rpoS locus is highly mutable by an unknown pathway, and that these mutations accumulate rapidly under common laboratory conditions.

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“…Downstream of rpoS, however, variations are quite common and even occur between different E. coli strains (28,37,83). However, nlpD can occur alone in bacteria that do not possess an rpoS gene, such as Haemophilus influenzae (55).…”

Section: Promoters Contributing To Rpos Transcriptionmentioning

confidence: 99%

Signal Transduction and Regulatory Mechanisms Involved in Control of the σ^S(RpoS) Subunit of RNA Polymerase

Hengge‐Aronis

2002

Microbiol Mol Biol Rev

851

791

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SUMMARY The σS (RpoS) subunit of RNA polymerase is the master regulator of the general stress response in Escherichia coli and related bacteria. While rapidly growing cells contain very little σS, exposure to many different stress conditions results in rapid and strong σS induction. Consequently, transcription of numerous σS-dependent genes is activated, many of which encode gene products with stress-protective functions. Multiple signal integration in the control of the cellular σS level is achieved by rpoS transcriptional and translational control as well as by regulated σS proteolysis, with various stress conditions differentially affecting these levels of σS control. Thus, a reduced growth rate results in increased rpoS transcription whereas high osmolarity, low temperature, acidic pH, and some late-log-phase signals stimulate the translation of already present rpoS mRNA. In addition, carbon starvation, high osmolarity, acidic pH, and high temperature result in stabilization of σS, which, under nonstress conditions, is degraded with a half-life of one to several minutes. Important cis-regulatory determinants as well as trans-acting regulatory factors involved at all levels of σS regulation have been identified. rpoS translation is controlled by several proteins (Hfq and HU) and small regulatory RNAs that probably affect the secondary structure of rpoS mRNA. For σS proteolysis, the response regulator RssB is essential. RssB is a specific direct σS recognition factor, whose affinity for σS is modulated by phosphorylation of its receiver domain. RssB delivers σS to the ClpXP protease, where σS is unfolded and completely degraded. This review summarizes our current knowledge about the molecular functions and interactions of these components and tries to establish a framework for further research on the mode of multiple signal input into this complex regulatory system.

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Gene Conservation and Loss in the mutS-rpoS Genomic Region of Pathogenic Escherichia coli

Cited by 46 publications

References 38 publications

Extended Virulence Genotype of Pathogenic Escherichia coli Isolates Carrying the afa-8 Operon: Evidence of Similarities between Isolates from Humans and Animals with Extraintestinal Infections

Extended Virulence Genotype of Pathogenic Escherichia coli Isolates Carrying the afa-8 Operon: Evidence of Similarities between Isolates from Humans and Animals with Extraintestinal Infections

Evolutionary loss of the rdar morphotype in Salmonella as a result of high mutation rates during laboratory passage

Signal Transduction and Regulatory Mechanisms Involved in Control of the σ^S(RpoS) Subunit of RNA Polymerase

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Gene Conservation and Loss in the mutS-rpoS Genomic Region of Pathogenic Escherichia coli

Cited by 46 publications

References 38 publications

Extended Virulence Genotype of Pathogenic Escherichia coli Isolates Carrying the afa-8 Operon: Evidence of Similarities between Isolates from Humans and Animals with Extraintestinal Infections

Extended Virulence Genotype of Pathogenic Escherichia coli Isolates Carrying the afa-8 Operon: Evidence of Similarities between Isolates from Humans and Animals with Extraintestinal Infections

Evolutionary loss of the rdar morphotype in Salmonella as a result of high mutation rates during laboratory passage

Signal Transduction and Regulatory Mechanisms Involved in Control of the σS(RpoS) Subunit of RNA Polymerase

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Signal Transduction and Regulatory Mechanisms Involved in Control of the σ^S(RpoS) Subunit of RNA Polymerase