Integration host factor is required for the DNA inversion that controls phase variation in Escherichia coli.

Eisenstein, Barry I.; Sweet, Deborah S.; Vaughn, Vicki; Friedman, David I.

doi:10.1073/pnas.84.18.6506

Cited by 133 publications

(119 citation statements)

References 34 publications

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“…Phase variation of type I fimbriae is also regulated by LRP, and lrp mutants have a reduced phase switching frequency . Moreover, there is an absolute requirement of IHF for phase variation of type I fimbriae, such that him mutants are unable to switch phase (Dorman and Higgins, 1987;Eisenstein et al, 1987). The ETEC K99 and K88 fimbriae are also regulated by LRP, which represses the expression of K88 fimbriae and activates the expression of K99 fimbriae (Braaten et al, 1992;Huisman et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Differential regulation of fasA and fasH expression of Escherichia coli 987P fimbriae by environmental cues

Edwards

Schifferli

1997

Molecular Microbiology

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SummaryAn early process in the pathogenesis of enteric bacteria is colonization of the intestinal epithelium leading to local multiplication, pathophysiological interactions with the host and further spreading. Attachment is typically mediated by bacterial fimbriae, which are selectively expressed during growth in the intestine. Here we report an analysis of the regulation of 987P fimbrial expression of enterotoxigenic Escherichia coli (ETEC). Expression of both fasH, the transcriptional activator of the 987P fimbrial genes, and fasA, the major fimbrial subunit, is regulated in response to a variety of environmental stimuli. We have found that expression of fasH is regulated in response to the carbon status of the growth medium by the cAMP-CRP complex. Moreover, fasH is regulated in response to both the nitrogen status of the growth medium and the external pH. Expression of fasA is activated by FasH, and is also selectively regulated in response to growth temperature by HNS. Regulation of fimbrial expression by carbon and/or nitrogen gradients is proposed to provide a mechanism that allows preferential colonization of different segments of the intestine by various enteropathogens, such as ETEC, enteropathogenic E. coli and Vibrio cholerae.

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Section: Discussionmentioning

confidence: 99%

Differential regulation of fasA and fasH expression of Escherichia coli 987P fimbriae by environmental cues

Edwards

Schifferli

1997

Molecular Microbiology

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“…Although inversion of thefim switch is considered to be controlled by the products of fimB, fimE, himA, himD, and hns (7,8,13,(14)(15)(16), little is known about the mechanism of the site-specific inversion and its potential regulation. We reported previously that rather than being slow and random, the fim switch is capable of high inversion frequencies (>0.7 per cell per generation) and is regulated by environmental conditions, including temperature and the amino acids alanine, leucine, isoleucine, and valine (11).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, it is known that himA and himD are required forfim recombination, although direct participation of the integration host factor has yet to be demonstrated. Two good consensus integration host factor-binding sites exist in and adjacent to thefim switch (7,8). Consequently, both the integration host factor and Lrp likely induce DNA bending to help align the inverted repeats in a juxtaposition.…”

Section: Discussionmentioning

confidence: 99%

The leucine-responsive regulatory protein binds to the fim switch to control phase variation of type 1 fimbrial expression in Escherichia coli K-12

1994

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Phase variation of type 1 fimbriation in Escherichia coli is associated with the site-specific recombination of a 314-bp DNA invertible element. Thefim switch directs transcription offimA, the major fimbrial subunit gene, in one orientation (on) but not the other (off). Switching requires eitherfimB (on-to-off or off-to-on inversion) or fimE (on-to-off inversion only) and is reduced sharply in strains containing lrp::TnlO mutations. Both fimE-promoted switching andfimB-promoted switching are stimulated by the amino acids alanine, isoleucine, leucine, and valine, and this regulation requires lrp. Here it is shown that the leucine-responsive regulatory protein (Lrp)

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“…Three global regulators have been described to affect switching induced by fimB and fimE, namely IHF, the histone-like protein H-NS, and the leucine-responsive element (Lrp) (37,(42)(43)(44)(45)(46). Lrp differentially regulates switching in various media and is involved in the stimulation of switching upon addition of aliphatic amino acids (47).…”

Section: Resultsmentioning

confidence: 99%

A site-specific recombinase is required for competitive root colonization by Pseudomonas fluorescens WCS365

Dekkers

Phoelich

Fits

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

129

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A colonization mutant of the efficient rootcolonizing biocontrol strain Pseudomonas fluorescens WCS365 is described that is impaired in competitive root-tip colonization of gnotobiotically grown potato, radish, wheat, and tomato, indicating a broad host range mutation. The colonization of the mutant is also impaired when studied in potting soil, suggesting that the defective gene also plays a role under more natural conditions. A DNA fragment that is able to complement the mutation for colonization revealed a multicistronic transcription unit composed of at least six ORFs with similarity to lppL, lysA, dapF, orf235͞233, xerC͞sss, and the largely incomplete orf238. The transposon insertion in PCL1233 appeared to be present in the orf235͞233 homologue, designated orf240. Introduction of a mutation in the xerC͞sss homologue revealed that the xerC͞sss gene homologue rather than orf240 is crucial for colonization. xerC in Escherichia coli and sss in Pseudomonas aeruginosa encode proteins that belong to the integrase family of site-specific recombinases, which play a role in phase variation caused by DNA rearrangements. The function of the xerC͞sss homologue in colonization is discussed in terms of genetic rearrangements involved in the generation of different phenotypes, thereby allowing a bacterial population to occupy various habitats. Mutant PCL1233 is assumed to be locked in a phenotype that is not well suited to compete for colonization in the rhizosphere. Thus we show the importance of phase variation in microbe-plant interactions.The use of microorganisms, including fluorescent Pseudomonas spp., to protect plants against soil-borne diseases is an alternative for the use of chemical pesticides. The biocontrol activity of these strains usually results from the production of one or more antifungal factors. The application of fluorescent Pseudomonas spp. and other plant-growth-promoting rhizobacteria is hampered by inconsistency of performance in the field (1, 2). Although the mechanisms underlying biocontrol are complex and diverse, the need to bring the plant-growthpromoting rhizobacteria cells and their antifungal factors to the right sites at the right time is universal. The importance of this process, designated as root colonization, is underscored in two studies. Schippers et al. (1) showed that inadequate colonization leads to decreased biocontrol activity, and Bull et al. (3) reported an inverse relation between the number of bacteria present on the wheat root and the number of take-all lesions seen on the plant. For these and other reasons, root colonization is often considered the limiting factor for biocontrol in the rhizosphere (1, 2).Two approaches were used in our laboratory to identify traits involved in root colonization. The first approach is to guess which traits are involved in colonization, isolate mutants in these traits, and then test these mutants for colonization in competition with the parental strain. With this approach, motility (4) and synthesis of the O-antigen of lipopolysa...

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Integration host factor is required for the DNA inversion that controls phase variation in Escherichia coli.

Cited by 133 publications

References 34 publications

Differential regulation of fasA and fasH expression of Escherichia coli 987P fimbriae by environmental cues

Differential regulation of fasA and fasH expression of Escherichia coli 987P fimbriae by environmental cues

The leucine-responsive regulatory protein binds to the fim switch to control phase variation of type 1 fimbrial expression in Escherichia coli K-12

A site-specific recombinase is required for competitive root colonization by Pseudomonas fluorescens WCS365

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