Effect of divalent cations on the ATPase activity of Escherichia coli SecA

It was found that Ca2+ stimulates the intrinsic SecA ATPase activity in the absence as well as in the presence of liposome, On the other hand, Mg2+, t he general cofactor for ATPase. did not affect the intrinsic SecA ATPase bu t reduced the portion of ATPase activity enhanced by. Ca2+. The enhancement of SecA ATPase activity correlated well with the increase in 8-anilino-1-n aphthalene-sulfonic acid binding of SecA, suggesting that increased exposur e of hydrophobic residues stimulates the enzyme activity. (C) 2001 Publishe d by Elsevier Science B.V. on behalf of the Federation of European Biochemi cal Societies.