Nucleotide sequence of dcrA, a Desulfovibrio vulgaris Hildenborough chemoreceptor gene, and its expression in Escherichia coli.

Abstract

The amino acid sequence of DcrA (Mr = 73,000), deduced from the nucleotide sequence of the dcrA gene from the anaerobic, sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough, indicates a structure similar to the methyl-accepting chemotaxis proteins from Escherichia coli, including a periplasmic NH2-terminal domain (Mr = 20,700) separated from the cytoplasmic COOH-terminal domain (Mr = 50,300) by a hydrophobic, membrane-spanning sequence of 20 amino acid residues. The sequence homology of DcrA and these methyl-accepting chemotaxis proteins is limited to the COOH-terminal domain. Analysis of dcrA-lacZ fusions in E. coli by Western blotting (immunoblotting) and activity measurements indicated a low-level synthesis of a membrane-bound fusion protein of the expected size (Mr = approximately 137,000). Expression of the dcrA gene under the control of the Desulfovibrio cytochrome c3 gene promoter and ribosome binding site allowed the identification of both full-length DcrA and its NH2-terminal domain in E. coli maxicells.