Regulated expression of a repressor protein: FadR activates iclR

Gui, Lizhen; Sunnarborg, Alden; LaPorte, David C.

doi:10.1128/jb.178.15.4704-4709.1996

Cited by 92 publications

(68 citation statements)

References 31 publications

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“…The first experiment involved examining the differences in gene expression between a fadR null mutant, strain JWC264, with the otherwise isogenic wild-type reference strain, strain MG1655. It should be noted that this fadR null allele, fadR613::Tn10 (also called fadR13::Tn10), has been widely used (19,20,26,29,30,47) and that recently the site of transposon insertion into the gene was determined (37). It seems likely that the truncated protein is degraded in vivo since the point of insertion is downstream of the regions important for DNA binding (54).…”

Section: Resultsmentioning

confidence: 99%

Escherichia coli FadR Positively Regulates Transcription of the fabB Fatty Acid Biosynthetic Gene

Campbell¹,

2001

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In Escherichia coli expression of the genes of fatty acid degradation (fad) is negatively regulated at the transcriptional level by FadR protein. In contrast the unsaturated fatty acid biosynthetic gene, fabA, is positively regulated by FadR. We report that fabB, a second unsaturated fatty acid biosynthetic gene, is also positively regulated by FadR. Genomic array studies that compared global transcriptional differences between wild-type and fadR-null mutant strains, as well as in cultures of each strain grown in the presence of exogenous oleic acid, indicated that expression of fabB was regulated in a manner very similar to that of fabA expression. A series of genetic and biochemical tests confirmed these observations. Strains containing both fabB and fadR mutant alleles were constructed and shown to exhibit synthetic lethal phenotypes, similar to those observed in fabA fadR mutants. A fadR strain was hypersensitive to cerulenin, an antibiotic that at low concentrations specifically targets the FabB protein. A transcriptional fusion of chloramphenicol acetyltransferase (CAT) to the fabB promoter produces lower levels of CAT protein in a strain lacking functional FadR. The ability of a putative FadR binding site within the fabB promoter to form a complex with purified FadR protein was determined by a gel mobility shift assay. These experiments demonstrate that expression of fabB is positively regulated by FadR.

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Section: Resultsmentioning

confidence: 99%

Escherichia coli FadR Positively Regulates Transcription of the fabB Fatty Acid Biosynthetic Gene

Campbell¹,

2001

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“…Another part of the FabR story that deserves attention is defining what mechanisms control the expression of fabR. Possibly, the fabR gene is controlled by another factor that ties UFA synthesis to other aspects of bacterial physiology in a fashion analogous to the control of acetate metabolism by FadR by virtue of its ability to control the expression of iclR, a transcriptional regulator of the glyoxylate bypass (38).…”

Section: Discussionmentioning

confidence: 99%

The FabR (YijC) Transcription Factor Regulates Unsaturated Fatty Acid Biosynthesis in Escherichia coli

Zhang

Marrakchi

Rock

2002

Journal of Biological Chemistry

106

119

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Unsaturated fatty acid biosynthesis is a vital facet ofEscherichia coli physiology and requires the expression of two genes, fabA and fabB, in the type II fatty acid synthase system. This study links the FabR (YijC) transcription factor to the regulation of unsaturated fatty acid content through the regulation of fabB gene expression. The yijC (fabR) gene was deleted by replacement with a selectable cassette, and the resulting strains (fabR::kan) possessed significantly elevated levels of unsaturated fatty acids, particularly cis-vaccenate, in their membrane phospholipids. The altered fatty acid composition was observed in the fabR::kan fabF1 double mutant pinpointing fabB as the condensing enzyme responsible for the increased cis-vaccenate production. The fabR::kan strains had 4-to 8-fold higher levels of fabB and a 2-to 3-fold increase in fabA transcripts as judged by Northern blotting, Affymetrix array analysis, and real-time PCR. FabR did not regulate the enzymes of fatty acid ␤-oxidation. The elevated level of fabB mRNA was reflected by higher condensing enzyme activity in fabR::kan fabF1 double mutants. Thus, FabR functions as a repressor that potently controls the expression of the fabB gene, which in turn, modulates the physical properties of the membrane by altering the level of unsaturated fatty acid production.

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“…Such analyses have been reported for eight DNAbinding proteins from E. coli: FadR (Gui et al, 1996), FruR (Negre et al, 1996), IclR (Pan et al, 1996), Lrp (Cui et al, 1995), MetJ (He et al, 1996), OmpR (Harlocker et al, 1995), OxyR (Toledano et al, 1994) and TrpR (Czernik et al, 1994).…”

Section: Comparison Of Natural and Selex Sitesmentioning

confidence: 99%

A comprehensive library of DNA-binding site matrices for 55 proteins applied to the complete Escherichia coli K-12 genome 1 1Edited by R. Ebright

Robison

McGuire

Church

1998

Journal of Molecular Biology

313

317

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A major mode of gene regulation occurs via the binding of speci®c proteins to speci®c DNA sequences. The availability of complete bacterial genome sequences offers an unprecedented opportunity to describe networks of such interactions by correlating existing experimental data with computational predictions. Of the 240 candidate Escherichia coli DNAbinding proteins, about 55 have DNA-binding sites identi®ed by DNA footprinting. We used these sites to construct recognition matrices, which we used to search for additional binding sites in the E. coli genomic sequence. Many of these matrices show a strong preference for non-coding DNA. Discrepancies are identi®ed between matrices derived from natural sites and those derived from SELEX (Systematic Evolution of Ligands by Exponential enrichment) experiments. We have constructed a database of these proteins and binding sites, called DPInteract (available at

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Regulated expression of a repressor protein: FadR activates iclR

Abstract: The control of the glyoxylate bypass operon (aceBAK) of Escherichia coli is mediated by two regulatory proteins, IclR and FadR. IclR is a repressor protein which has previously been shown to bind to a site which overlaps the aceBAK promoter.

Cited by 92 publications

References 31 publications

Escherichia coli FadR Positively Regulates Transcription of the fabB Fatty Acid Biosynthetic Gene

Escherichia coli FadR Positively Regulates Transcription of the fabB Fatty Acid Biosynthetic Gene

The FabR (YijC) Transcription Factor Regulates Unsaturated Fatty Acid Biosynthesis in Escherichia coli

A comprehensive library of DNA-binding site matrices for 55 proteins applied to the complete Escherichia coli K-12 genome 1 1Edited by R. Ebright

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