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Identification of promoter and stringent regulation of transcription of the fabH, fabD and fabG genes encoding fatty acid biosynthetic enzymes of Escherichia coli.

ABSTRACT: In Escherichia coli, amino acid starvation results in the coordinate inhibition of a variety of metabolic activities, including fatty acid and phospholipid biosynthesis. By using primer extension analysis we identified the fabH promoter responsible for transcription of the fabH, fabD and fabG genes encoding fatty acid biosynthetic enzymes. The response of the fabH promoter to amino acid starvation was determined in vivo. Transcripts originating from the fabH promoter were quantified by employing a ribonuclease protection assay. The fabH promoter was subject to relA-dependent stringent control and was repressed approximately 4-fold upon amino acid starvation. The results suggest that inhibition of transcription initiation of lipid biosynthetic genes in starved cells contributes to the stringent control of lipid biosynthesis.

SUBMITTER: Podkovyrov SM

PROVIDER: S-EPMC145835 | biostudies-other | 1996 May

REPOSITORIES: biostudies-other

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Identification of promoter and stringent regulation of transcription of the fabH, fabD and fabG genes encoding fatty acid biosynthetic enzymes of Escherichia coli.

Podkovyrov S M SM Larson T J TJ

Nucleic acids research 19960501 9

In Escherichia coli, amino acid starvation results in the coordinate inhibition of a variety of metabolic activities, including fatty acid and phospholipid biosynthesis. By using primer extension analysis we identified the fabH promoter responsible for transcription of the fabH, fabD and fabG genes encoding fatty acid biosynthetic enzymes. The response of the fabH promoter to amino acid starvation was determined in vivo. Transcripts originating from the fabH promoter were quantified by employing ...[more]

PMID: 8649995

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Project description:BackgroundThe Escherichia coli response regulator NarL controls transcription of genes involved in nitrate respiration during anaerobiosis. NarL consists of two domains joined by a linker that wraps around the interdomain interface. Phosphorylation of the NarL N-terminal receiver domain (RD) releases the, otherwise sequestered, C-terminal output domain (OD) that subsequently binds specific DNA promoter sites to repress or activate gene expression. The aim of this study is to investigate the extent to which the NarL OD and RD function independently to regulate transcription, and the affect of the linker on OD function.ResultsNarL OD constructs containing different linker segments were examined for their ability to repress frdA-lacZ or activate narG-lacZ reporter fusion genes. These in vivo expression assays revealed that the NarL OD, in the absence or presence of linker helix α6, constitutively repressed frdA-lacZ expression regardless of nitrate availability. However, the presence of the linker loop α5-α6 reversed this repression and also showed impaired DNA binding in vitro. The OD alone could not activate narG-lacZ expression; this activity required the presence of the NarL RD. A footprint assay demonstrated that the NarL OD only partially bound recognition sites at the narG promoter, and the binding affinity was increased by the presence of the phosphorylated RD. Analytical ultracentrifugation used to examine domain oligomerization showed that the NarL RD forms dimers in solution while the OD is monomeric.ConclusionsThe NarL RD operates as an on-off switch to occlude or release the OD in a nitrate-responsive manner, but has additional roles to directly stimulate transcription at promoters for which the OD lacks independent function. One such role of the RD is to enhance the DNA binding affinity of the OD to target promoter sites. The data also imply that NarL phosphorylation results in RD dimerization and in the separation of the entire linker region from the OD.

Dataset Information

Identification of promoter and stringent regulation of transcription of the fabH, fabD and fabG genes encoding fatty acid biosynthetic enzymes of Escherichia coli.

Publications

Identification of promoter and stringent regulation of transcription of the fabH, fabD and fabG genes encoding fatty acid biosynthetic enzymes of Escherichia coli.

Similar Datasets

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