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Regulation of transcription of genes required for fatty acid transport and unsaturated fatty acid biosynthesis in Escherichiacoli by FadR
Author(s) -
DiRusso Concetta O.,
Metzger Amy K.,
Heimert Tamra L.
Publication year - 1993
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1993.tb01122.x
Subject(s) - biology , promoter , transcription (linguistics) , biochemistry , gene , dna , microbiology and biotechnology , repressor , rna polymerase , transcription factor , escherichia coli , gene expression , linguistics , philosophy
Summary Fatty acid biosynthesis and fatty acid degradation in Escherichiacoli are co‐ordinately regulated at the level of transcription by the product of the fadR gene, FadR. In the present work we investigate FadR interaction with the fabA and fadL promoters. The FadR‐responsive operator within fabA , O A , was localized to a region −47 to −31 base pairs relative to the start of transcription using DNase I protection studies. The promoter and untranslated leader within fadL had two binding sites for FadR, O L1 at −25 to −9 and O L2 at −1 to +16 relative to the start of transcription. The binding affinity of FadR for O A and O L1 or O L2 was lower than that for the single site within fadB (O B ) as measured using protein‐DNA gel retention assays. Overall, these experiments demonstrated that the affinity of FadR binding for DNA containing the fadB, fadL and fabA promoters was O B > O L1 , O L2 > O A . We could not distinguish separate binding affinities for O L1 or O L2 . We demonstrated repression of fadL transcription and activation of fabA transcription in vitro using run‐off transcription assays containing purified FadR and RNA polymerase.