Transcriptional regulation through RfaH contributes to intestinal colonization by<i>Escherichia coli</i>

Nagy, Gábor; Dobrindt, Ulrich; Grozdanov, Lubomir; Hacker, Jörg; Emödy, Levente

doi:10.1016/j.femsle.2005.01.038

Cited by 16 publications

(12 citation statements)

References 40 publications

(71 reference statements)

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“…The loss of RfaH results in lipopolysaccharide chains of various lengths and confers sensitivity to bile salts, detergents, and antibiotics (12). A polar mini-Tn 5 insertion into MG1655 waaQ ( rfaQ ), the first gene in the waa operon regulated by RfaH (5), produces similar phenotypes (13).…”

Section: Resultsmentioning

confidence: 99%

A Screen for rfaH Suppressors Reveals a Key Role for a Connector Region of Termination Factor Rho

Artsimovitch

2017

mBio

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RfaH activates horizontally acquired operons that encode lipopolysaccharide core components, pili, toxins, and capsules. Unlike its paralog NusG, which potentiates Rho-mediated silencing, RfaH strongly inhibits Rho. RfaH is recruited to its target operons via a network of contacts with an elongating RNA polymerase (RNAP) and a specific DNA element called ops to modify RNAP into a pause- and NusG-resistant state. rfaH null mutations confer hypersensitivity to antibiotics and detergents, altered susceptibility to bacteriophages, and defects in virulence. Here, we carried out a selection for suppressors that restore the ability of a ΔrfaH mutant Escherichia coli strain to grow in the presence of sodium dodecyl sulfate. We isolated rho, rpoC, and hns suppressor mutants with changes in regions previously shown to be important for their function. In addition, we identified mutants with changes in an unstructured region that connects the primary RNA-binding and helicase domains of Rho. The connector mutants display strong defects in vivo, consistent with their ability to compensate for the loss of RfaH, and act synergistically with bicyclomycin (BCM), which has been recently shown to inhibit Rho transformation into a translocation-competent state. We hypothesize that the flexible connector permits the reorientation of Rho domains and serves as a target for factors that control the motor function of Rho allosterically. Our results, together with the existing data, support a model in which the connector segment plays a hitherto overlooked role in the regulation of Rho-dependent termination.

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Section: Resultsmentioning

confidence: 99%

A Screen for rfaH Suppressors Reveals a Key Role for a Connector Region of Termination Factor Rho

Artsimovitch

2017

mBio

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“…Some of these also affect LPS such as rfaH (EC958_4322), encoding a known regulator required for LPS biosynthesis [51], [52] and virulence of pathogenic E. coli strains [53], [54], whilst others represent genes that have not previously been shown to be associated with serum resistance. The murein lipoprotein gene lpp (EC958_1897) showed the greatest difference between the test and control samples (logFC of −10), followed by pgm (EC958_0806), encoding phosphoglucomutase.…”

Section: Resultsmentioning

confidence: 99%

The Serum Resistome of a Globally Disseminated Multidrug Resistant Uropathogenic Escherichia coli Clone

et al. 2013

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Escherichia coli ST131 is a globally disseminated, multidrug resistant clone responsible for a high proportion of urinary tract and bloodstream infections. The rapid emergence and successful spread of E. coli ST131 is strongly associated with antibiotic resistance; however, this phenotype alone is unlikely to explain its dominance amongst multidrug resistant uropathogens circulating worldwide in hospitals and the community. Thus, a greater understanding of the molecular mechanisms that underpin the fitness of E. coli ST131 is required. In this study, we employed hyper-saturated transposon mutagenesis in combination with multiplexed transposon directed insertion-site sequencing to define the essential genes required for in vitro growth and the serum resistome (i.e. genes required for resistance to human serum) of E. coli EC958, a representative of the predominant E. coli ST131 clonal lineage. We identified 315 essential genes in E. coli EC958, 231 (73%) of which were also essential in E. coli K-12. The serum resistome comprised 56 genes, the majority of which encode membrane proteins or factors involved in lipopolysaccharide (LPS) biosynthesis. Targeted mutagenesis confirmed a role in serum resistance for 46 (82%) of these genes. The murein lipoprotein Lpp, along with two lipid A-core biosynthesis enzymes WaaP and WaaG, were most strongly associated with serum resistance. While LPS was the main resistance mechanism defined for E. coli EC958 in serum, the enterobacterial common antigen and colanic acid also impacted on this phenotype. Our analysis also identified a novel function for two genes, hyxA and hyxR, as minor regulators of O-antigen chain length. This study offers novel insight into the genetic make-up of E. coli ST131, and provides a framework for future research on E. coli and other Gram-negative pathogens to define their essential gene repertoire and to dissect the molecular mechanisms that enable them to survive in the bloodstream and cause disease.

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“…HldE is a bifunctional protein with two distinct functional domains, an N-terminal region with homology to the ribokinase superfamily (HldE1 domain) and a C-terminal region with homology to the cytidylyltransferase superfamily (HldE2 domain) [32]. Some reports have shown that deep rough LPS core mutants of Enterobacteriaceae; waaG , rfaH , and waaQ mutants of E. coli and the waaG mutant of Salmonella Typhimurium; failed to colonize the intestine [33], [34], [35]. However, it has not been systematically investigated yet what role the LPS structure in these species might play in biofilm formation on an abiotic surface.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Biofilm Formation by Escherichia coli LPS Mutants Defective in Hep Biosynthesis

et al. 2012

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Lipopolysaccharide (LPS) is the major component of the surface of Gram-negative bacteria and its polysaccharide portion is situated at the outermost region. We investigated the relationship between the polysaccharide portion of LPS and biofilm formation using a series of Escherichia coli mutants defective in genes earlier shown to affect the LPS sugar compositions. Biofilm formation by a deep rough LPS mutant, the hldE strain, was strongly enhanced in comparison with the parental strain and other LPS mutants. The hldE strain also showed a phenotype of increased auto-aggregation and stronger cell surface hydrophobicity compared to the wild-type. Similar results were obtained with another deep rough LPS mutant, the waaC strain whose LPS showed same molecular mass as that of the hldE strain. Confocal laser scanning microscopy (CLSM) analysis and biofilm formation assay using DNase I revealed that biofilm formation by the hldE strain was dependent on extracellular DNA. Furthermore, a loss of flagella and an increase in amount of outer membrane vesicles in case of the hldE strain were also observed by transmission electron microscopy and atomic force microscopy, respectively. In addition, we demonstrated that a mutation in the hldE locus, which alters the LPS structure, caused changes in both expression and properties of several surface bacterial factors involved in biofilm formation and virulence. We suggest that the implication of these results should be considered in the context of biofilm formation on abiotic surfaces, which is frequently associated with nosocominal infections such as the catheter-associated infections.

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Transcriptional regulation through RfaH contributes to intestinal colonization byEscherichia coli

Cited by 16 publications

References 40 publications

A Screen for rfaH Suppressors Reveals a Key Role for a Connector Region of Termination Factor Rho

A Screen for rfaH Suppressors Reveals a Key Role for a Connector Region of Termination Factor Rho

The Serum Resistome of a Globally Disseminated Multidrug Resistant Uropathogenic Escherichia coli Clone

Enhanced Biofilm Formation by Escherichia coli LPS Mutants Defective in Hep Biosynthesis

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