Analysis of SecA Dimerization in Solution
| Autor: | Jun Zhang, Michael L. Gross, Andy J. Wowor, Eric R. May, Dongmei Yu, Debra A. Kendall, Yuetian Yan, James L. Cole, Sarah M. Auclair |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Stereochemistry
Dimer Crystallography X-Ray Antiparallel (biochemistry) environment and public health Biochemistry Article Motor protein 03 medical and health sciences chemistry.chemical_compound Protein structure Bacterial Proteins Escherichia coli Inner membrane Protein Structure Quaternary 030304 developmental biology Preprotein binding Adenosine Triphosphatases 0303 health sciences SecA Proteins biology Membrane transport protein 030302 biochemistry & molecular biology Membrane Transport Proteins Amino Acid Substitution chemistry biology.protein bacteria Protein Multimerization SEC Translocation Channels Bacillus subtilis |
| Zdroj: | Biochemistry |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi500348p |
| Popis: | The Sec pathway mediates translocation of protein across the inner membrane of bacteria. SecA is a motor protein that drives translocation of preprotein through the SecYEG channel. SecA reversibly dimerizes under physiological conditions, but different dimer interfaces have been observed in SecA crystal structures. Here, we have used biophysical approaches to address the nature of the SecA dimer that exists in solution. We have taken advantage of the extreme salt sensitivity of SecA dimerization to compare the rates of hydrogen–deuterium exchange of the monomer and dimer and have analyzed the effects of single-alanine substitutions on dimerization affinity. Our results support the antiparallel dimer arrangement observed in one of the crystal structures of Bacillus subtilis SecA. Additional residues lying within the preprotein binding domain and the C-terminus are also protected from exchange upon dimerization, indicating linkage to a conformational transition of the preprotein binding domain from an open to a closed state. In agreement with this interpretation, normal mode analysis demonstrates that the SecA dimer interface influences the global dynamics of SecA such that dimerization stabilizes the closed conformation. |
| Databáze: | OpenAIRE |
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