Modulation of Lrp action in Escherichia coli by leucine: effects on non-specific binding of Lrp to DNA

Chen, Shaolin; Hao, Zhiqi; Bieniek, Eva; Calvo, Joseph M.

doi:10.1006/jmbi.2000.5209

Cited by 31 publications

(41 citation statements)

References 32 publications

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“…The binding of leucine by Lrp either stimulates or reduces the promoter activity of its target genes or operons (Platko & Calvo, 1993). In addition, the non-specific binding of Lrp to DNA affects the expression of many genes, and this binding varies with the nutrient conditions and growth phase (Chen et al, 2001). To confirm the involvement of Lrp in the regulation of the LEE genes, we examined the response of the LEE genes to leucine.…”

Section: Lrp Mediates the Butyrate Responsementioning

confidence: 99%

Regulation of virulence by butyrate sensing in enterohaemorrhagic Escherichia coli

Nakanishi

Tashiro²,

Kuhara³

et al. 2009

Microbiology

134

155

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Enterohaemorrhagic Escherichia coli (EHEC) colonizes and proliferates at the mucosal surface, inducing severe diarrhoea. Short-chain fatty acids (SCFAs) are abundant in the intestine owing to the metabolic activity of microflora, and are important for colonic health. We found that, although a high concentration of SCFAs inhibited the growth of EHEC, at low concentrations, the SCFAs markedly enhanced the expression of the virulence genes required for cell adherence and the induction of attaching and effacing (A/E) lesions. Of the SCFAs tested, butyrate markedly enhanced the expression of these virulence-associated genes, even at the low concentration of 1.25 mM, but acetate and propionate showed only a small effect at concentrations higher than 40 mM. Butyrate enhanced the promoter activity of the LEE1 operon, which encodes a global regulator of the LEE genes, Ler. This enhancement was dependent on a regulator, PchA. Butyrate sensing was completely abrogated by the deletion of lrp, the gene for the leucine-responsive regulatory protein, Lrp. Expression of a constitutively active mutant of Lrp enhanced the expression of the LEE genes in the absence of butyrate, and a response-defective Lrp derivative reduced the response to butyrate. Thus, upon entering the distal ileum, EHEC may respond to the higher butyrate level via Lrp by increasing its virulence expression, leading to efficient colonization of the target niche.

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Section: Lrp Mediates the Butyrate Responsementioning

confidence: 99%

Regulation of virulence by butyrate sensing in enterohaemorrhagic Escherichia coli

Nakanishi

Tashiro²,

Kuhara³

et al. 2009

Microbiology

134

155

View full text Add to dashboard Cite

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“…This mutual binding exclusion effect is reduced from 10-fold to only about 2-fold when unsupercoiled DNAs are used (unpublished data), showing a strong dependence on DNA topology. Because Lrp is known to form higher oligomers under certain conditions (19,20) and bend DNA (21), one possible mechanism is that the conformation of pap sites 4-6 might be altered as a result of a binding of Lrp at sites 1-3 located 102 bp away (measured from site 2 to site 5) (Fig. 1).…”

mentioning

confidence: 99%

Self-perpetuating epigenetic pili switches in bacteria

Hernday

Krabbe

Braaten

et al. 2002

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

132

204

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Cis-and Trans-Acting Pap Switch ComponentsB acteria have developed phase variation mechanisms to control cell surface pili-adhesin complexes between expression (phase ON) and nonexpression (phase OFF) states. Pili phase variation can occur by site specific (1, 2) and homologous recombination (3) mechanisms. In addition, a large group of pili operons including pyelonephritis-associated pili (pap) are regulated by an epigenetic switch directly controlled by DNA methylation pattern formation (4, 5). The focus of this paper is on the mechanisms by which the phase OFF and phase ON states are perpetuated, the transition between phase OFF and phase ON states, and the external inputs that control phase switching.

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“…At that concentration in vitro, Lrp exists mainly as an octamer or hexadecamer, and millimolar concentrations of leucine promote conversion of hexadecamer to octamer. For E. coli grown in a minimal medium, about 60% of the total Lrp is bound nonspecifically to DNA, but the concentration of free Lrp is high enough that some mixture of octamers and hexadecamers is expected in vivo (4,5).…”

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confidence: 99%

ilvIH Operon Expression in Escherichia coli Requires Lrp Binding to Two Distinct Regions of DNA

2002

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The leucine-responsive regulatory protein Lrp regulates the expression of a number of operons in Escherichia coli, including the ilvIH operon. Earlier in vitro experiments showed purified Lrp binding to two regions of DNA proximal to the ilvIH promoter, an upstream region (؊260 to ؊190) and a downstream region (؊150 to ؊40). The effect of mutations in these regions on ilvIH promoter expression in vivo led to the proposal that activation of transcription required Lrp binding to downstream sites 3, 4, 5, and 6. Binding of Lrp to upstream sites 1 and 2 seemed to enhance promoter expression but was not absolutely required (Q. Wang and J. M. Calvo, J. Mol. Biol. 229:306-318, 1993). Here we present data that require a reevaluation of the above conclusion. Constructs having either a deletion of DNA or a 100-bp substitution of DNA upstream of position ؊160 showed no ilvIH promoter activity in vivo. These results unambiguously establish that DNA at or upstream of position ؊160 is required for ilvIH promoter expression. Together with previous results, we conclude that Lrp bound at downstream sites is necessary but not sufficient for promoter activation. In addition, insertion of 4, 6, 8, or 10 bp between the upstream and downstream regions also resulted in a very strong reduction of in vivo promoter expression, even though the binding of Lrp in vitro was not greatly affected by these mutations. Closer inspection showed that the affinity of Lrp for the upstream region of all of these constructs was about the same but that Lrp bound to the downstream region of the wild-type construct with a higher degree of cooperativity than in the case of the others. These mutations may have reduced promoter activity in vivo by eliminating a binding site for some transcription factor other than Lrp. Alternatively, the small-addition mutations may have affected the geometry of these complexes, preventing either an interaction between Lrps bound at upstream and downstream sites (which might be necessary for promoter expression) or preventing the positioning of Lrp bound at upstream sites for productive interaction with the promoter.

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Modulation of Lrp action in Escherichia coli by leucine: effects on non-specific binding of Lrp to DNA

Cited by 31 publications

References 32 publications

Regulation of virulence by butyrate sensing in enterohaemorrhagic Escherichia coli

Regulation of virulence by butyrate sensing in enterohaemorrhagic Escherichia coli

Self-perpetuating epigenetic pili switches in bacteria

ilvIH Operon Expression in Escherichia coli Requires Lrp Binding to Two Distinct Regions of DNA

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