Effect of divalent cations on the ATPase activity of Escherichia coli SecA
1Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 373-1 Kusong-Dong, Yusong-Gu, 305-701, Taejon, South Korea.
Abstract:
It was found that Ca(2+) stimulates the intrinsic SecA ATPase activity in the absence as well as in the presence of liposome. On the other hand, Mg(2+), the general cofactor for ATPase, did not affect the intrinsic SecA ATPase but reduced the portion of ATPase activity enhanced by Ca(2+). The enhancement of SecA ATPase activity correlated well with the increase in 8-anilino-1-naphthalene-sulfonic acid binding of SecA, suggesting that increased exposure of hydrophobic residues stimulates the enzyme activity.
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