Document Type
Article
Language
eng
Format of Original
9 p.
Publication Date
4-2005
Publisher
American Society for Biochemistry and Molecular Biology
Source Publication
Journal of Biological Chemistry
Source ISSN
0021-9258
Abstract
Escherichia coli SecA uses ATP to drive the transport of proteins across cell membranes. Glutamate 210 in the “DEVD” Walker B motif of the SecA ATP-binding site has been proposed as the catalytic base for ATP hydrolysis (Hunt, J. F., Weinkauf, S., Henry, L., Fak, J. J., McNicholas, P., Oliver, D. B., and Deisenhofer, J. (2002) Science 297, 2018–2026). Consistent with this hypothesis, we find that mutation of glutamate 210 to aspartate results in a 90-fold reduction of the ATP hydrolysis rate compared with wild type SecA, 0.3 s–1versus 27 s–1, respectively. SecA-E210D also releases ADP at a slower rate compared with wild type SecA, suggesting that in addition to serving as the catalytic base, glutamate 210 might aid turnover as well. Our results contradict an earlier report that proposed aspartate 133 as the catalytic base (Sato, K., Mori, H., Yoshida, M., and Mizushima, S. (1996) J. Biol. Chem. 271, 17439–17444). Re-evaluation of the SecA-D133N mutant used in that study confirms its loss of ATPase and membrane translocation activities, but surprisingly, the analogous SecA-D133A mutant retains full activity, revealing that this residue does not play a key role in catalysis.
Recommended Citation
Zito, Christopher R.; Antony, Edwin; Hunt, John F.; Oliver, Donald B.; and Hingorani, Manju M., "Role of a Conserved Glutamate Residue in the Escherichia coli SecA ATPase Mechanism" (2005). Biological Sciences Faculty Research and Publications. 414.
https://epublications.marquette.edu/bio_fac/414
Comments
Published version. Journal of Biological Chemistry, Vol. 280, No. 15 (April 2005): 14611-14619. DOI. © 2005 The American Society for Biochemistry and Molecular Biology, Inc. Used with permission.
Edwin Antony was affiliated with Wesleyan University at time of publication.