The Dimer Interface of SecA

Autor: James L. Cole, Andy J. Wowor, Dongmei Yu, Sarah M. Auclair, Ping Zhao, Debra A. Kendall
Rok vydání: 2012
Předmět:
Zdroj: Biophysical Journal. 102:258a
ISSN: 0006-3495
DOI: 10.1016/j.bpj.2011.11.1422
Popis: In prokaryotes and eukaryotes, the general secretion (Sec) pathway transports preproteins across membranes. The ATPase SecA mediates preprotein translocation through the integral membrane channel SecYEG. SecA exists in a monomer-dimer equilibrium at micromolar concentrations that is highly sensitive to salt concentration and temperature (1,2). Interestingly, the published crystal structures of SecA reveal different dimerization interfaces. It is unclear which of these structures, if any, represents the physiological dimer interface. In order to address this question, we created mutations based on the alternative dimer interfaces observed in the crystal structures. We determined the effect of alanine mutation of interfacial residues on dimerization energetics using sedimentation velocity. Residues for mutagenesis were chosen by computational alanine scanning using the program ROBETTA. The residues selected for alanine mutations were predicted to destabilize the interface by at least 1 kcal/mol. The results are consistent with one of the crystal structures and suggest that it represents the solution dimer interface.1. Woodbury, R. L., Hardy, S. J. & Randall, L. L. (2002). Complex behavior in solution of homodimeric SecA. Protein Sci 11, 875-882.2. Wowor, A. J., Yu, D., Kendall, D. A. & Cole, J. L. (2011). Energetics of SecA dimerization. J Mol Biol 408, 87-98.
Databáze: OpenAIRE
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