MEMBRANE TOPOLOGY OF THE METHYL-ACCEPTING CHEMOTAXIS PROTEIN DCRA FROM DESULFOVIBRIO-VULGARIS HILDENBOROUGH

Alkaline phosphatase fusions were used to study the membrane topology of DcrA, a protein of 668 amino acids from Desulfovibrio vulgaris Hild enborough, which has two potentially membrane-spanning hydrophobic seq uences at residues 11 to 29 and 188 to 207. A fusion at amino acid res idue 170 in the proposed periplasmic domain exhibited high alkaline ph osphatase activity, while low activity was observed for a fusion at am ino acid residue 284 in the proposed cytoplasmic domain. The data supp ort a topological model for DcrA similar to that of the methyl-accepti ng chemotaxis proteins of the enteric bacteria.