Nucleotide sequence encoding the flavoprotein and hydrophobic subunits of the succinate dehydrogenase of Escherichia coli

Publisher Website
Google Scholar
Abstract
The nucleotide sequence of a 3614 base-pair segment of DNA containing the sdhA gene, encoding the flavoprotein subunit of succinate dehydrogenase of E. coli, and 2 genes, sdhC and sdhD, encoding small hydrophobic subunits, was determined. Together with the Fe-S protein gene (sdhB) these genes form an operon (sdhCDAB) situated between the citrate synthase gene (gltA) and 2-oxoglutarate dehydrogenase complex genes (sucAB). Transcription of the gltA and sdhCDAB gene appears to diverge from a single intergenic region that contains 2 pairs of potential promoter sequences and 2 putative CRP (cAMP receptor protein)-binding sites. The sdhA strctural gene comprises 1761 base-pairs (587 codons, excluding the initiation codon, AUG) and it encodes a polypeptide of MW 64,268 that is strikingly homologous with the flavoprotein subunit of fumarate reductase (frdA gene product). The FAD-binding region, including the histidine residue at the FAD-attachment site, was identified by its homology with other flavoproteins and with the flavopeptide of the bovine heart mitochondrial succinate dehydrogenase. Potential active-site cysteine and histidine residues were also indicated by the comparisons. The sdhC (384 base-pairs) and sdhD (342 base-pairs) structural genes encode 2 strongly hydrophobic proteins of MW 14,167 and 12,792, respectively. These proteins resemble in size and composition, but not sequence, the membrane anchor proteins of fumarate reductase (the frdC and frdD gene products).