Membrane topology of the methyl-accepting chemotaxis protein DcrA fromDesulfovibrio vulgaris Hildenborough

Alkaline phosphatase fusions were used to study the membrane topology of DcrA, a protein of 668 amino acids fromDesulfovibrio vulgaris Hildenborough, which has two potentially membrane-spanning hydrophobic sequences at residues 11 to 29 and 188 to 207. A fusion at amino acid residue 170 in the proposed periplasmic domain exhibited high alkaline phosphatase activity, while low activity was observed for a fusion at amino acid residue 284 in the proposed cytoplasmic domain. The data support a topological model for DcrA similar to that of the methyl-accepting chemotaxis proteins of the enteric bacteria.