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.

Transcription of the Escherichia coli Fatty Acid Synthesis OperonfabHDGIs Directly Activated by FadR and Inhibited by ppGpp

“…The activity of the fabH promoter increased modestly but reproducibly in the ⌬relA ⌬spoT mutant, it increased to a greater extent in the ⌬dksA mutant, and it decreased in the spoT203 strain (Fig. 6A, left panel), consistent with the negative regulation of this operon by ppGpp proposed previously (32) and with the requirement for DksA for regulation by ppGpp (50). Similar conclusions were reached from analysis of the fabHlacZ and fabA-lacZ transcriptional fusions in wild-type versus ⌬dksA strains (see Fig.…”

“…It was reported previously that the expression of fabH was inhibited during the stringent response (32). fabHDG gene expression was also downregulated by ppGpp induction in a genome-wide transcriptome study (34).…”

“…Other reports suggest that ppGpp might control fatty acid synthesis at the level of transcription. For example, expression of the accABCD operon (encoding acetyl-CoA carboxylase) is growth rate dependent (31), and the promoter driving expression of the fabHDG genes encoding the enzymes in the fatty acid elongation cycle is subject to the stringent response (32). Consistent with these reports, transcriptome studies provided evidence for a decrease in fatty acid synthesis gene expression during the stringent response (e.g., accC, accD, fabH, fabF, and fabD) (33,34).…”

“…The control of this region is complex, with previous reports describing at least 4 different promoters and transcripts corresponding to different subsets of the genes in the locus (Fig. 1A) (32,35,37,38).…”

(p)ppGpp modulates cell size and the initiation of DNA replication in Caulobacter crescentus in response to a block in lipid biosynthesis

“…In addition to modulating cell size, (p)ppGpp was found to inhibit the transcription of fabH and other lipid biosynthetic genes in E. coli (My et al, 2013;Podkovyrov & Larson, 1996). The transcription of a group of lipid biosynthetic genes (including plsX, which is in the same operon as fabH) was also inhibited in carbon-starved C. crescentus (Boutte & Crosson, 2011), suggesting a conserved regulatory pathway.…”