|
|
||||||||
1 School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660, USA
2 Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, USA
Reprint requests to: Dr. Linda L. Randall, Department of Biochemistry, 117 Schweitzer Hall, University of Missouri, Columbia, Missouri 65211; fax: (573) 882-5635.
SecA, a homodimeric protein involved in protein export in Escherichia coli, exists in the cell both associated with the membrane translocation apparatus and free in the cytosol. SecA is a multifunctional protein involved in protein localization and regulation of its own expression. To carry out these functions, SecA interacts with a variety of proteins, phospholipids, nucleotides, and nucleic acid and shows two enzymic activities. It is an ATPase and a helicase. Its role during protein localization involves interaction with the precursor polypeptides to be exported, the cytosolic chaperone SecB, and the SecY subunit of the membrane-associated translocase, as well as with acidic phospholipids. At the membrane, SecA undergoes a cycle of binding and hydrolysis of ATP coupled to conformational changes that result in translocation of precursors through the cytoplasmic membrane. The helicase activity of SecA and its affinity for its mRNA are involved in regulation of its own expression. SecA has been reported to exist in at least two conformational states during its functional cycle. Here we have used analytical centrifugation, as well as column chromatography coupled with multiangle light scatter, to show that in solution SecA undergoes at least two monomer-dimer equilibrium reactions that are sensitive to temperature and to concentration of salt.
Keywords: SecA; protein export; homodimer; equilibrium constant; light scatter
![]()
CiteULike
Connotea
Del.icio.us
Digg
Reddit
Technorati What's this?
This article has been cited by other articles:
![]() |
H. Wang, B. Na, H. Yang, and P. C. Tai Additional In Vitro and In Vivo Evidence for SecA Functioning as Dimers in the Membrane: Dissociation into Monomers Is Not Essential for Protein Translocation in Escherichia coli J. Bacteriol., February 15, 2008; 190(4): 1413 - 1418. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. A. M. Gold, A. Robson, A. R. Clarke, and I. Collinson Allosteric Regulation of SecA: MAGNESIUM-MEDIATED CONTROL OF CONFORMATION AND ACTIVITY J. Biol. Chem., June 15, 2007; 282(24): 17424 - 17432. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. N. Patel, V. F. Smith, and L. L. Randall Characterization of three areas of interactions stabilizing complexes between SecA and SecB, two proteins involved in protein export. Protein Sci., June 1, 2006; 15(6): 1379 - 1386. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. B. Jilaveanu and D. Oliver SecA Dimer Cross-Linked at Its Subunit Interface Is Functional for Protein Translocation J. Bacteriol., January 1, 2006; 188(1): 335 - 338. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. de Keyzer, E. O. van der Sluis, R. E. J. Spelbrink, N. Nijstad, B. de Kruijff, N. Nouwen, C. van der Does, and A. J. M. Driessen Covalently Dimerized SecA Is Functional in Protein Translocation J. Biol. Chem., October 21, 2005; 280(42): 35255 - 35260. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. T. Doerrler and C. R. H. Raetz Loss of Outer Membrane Proteins without Inhibition of Lipid Export in an Escherichia coli YaeT Mutant J. Biol. Chem., July 29, 2005; 280(30): 27679 - 27687. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. B. Jilaveanu, C. R. Zito, and D. Oliver Dimeric SecA is essential for protein translocation PNAS, May 24, 2005; 102(21): 7511 - 7516. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Or, D. Boyd, S. Gon, J. Beckwith, and T. Rapoport The Bacterial ATPase SecA Functions as a Monomer in Protein Translocation J. Biol. Chem., March 11, 2005; 280(10): 9097 - 9105. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Nakatogawa, A. Murakami, H. Mori, and K. Ito SecM facilitates translocase function of SecA by localizing its biosynthesis Genes & Dev., February 15, 2005; 19(4): 436 - 444. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. R. Osborne, W. M. Clemons Jr., and T. A. Rapoport A large conformational change of the translocation ATPase SecA PNAS, July 27, 2004; 101(30): 10937 - 10942. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. L. Randall, J. M. Crane, G. Liu, and S. J.S. Hardy Sites of interaction between SecA and the chaperone SecB, two proteins involved in export Protein Sci., April 1, 2004; 13(4): 1124 - 1133. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. de Keyzer, C. van der Does, T. G. Kloosterman, and A. J. M. Driessen Direct Demonstration of ATP-dependent Release of SecA from a Translocating Preprotein by Surface Plasmon Resonance J. Biol. Chem., August 8, 2003; 278(32): 29581 - 29586. [Abstract] [Full Text] [PDF] |
||||
![]() |
H.-W. Wang, Y. Chen, H. Yang, X. Chen, M.-X. Duan, P. C. Tai, and S.-F. Sui Ring-like pore structures of SecA: Implication for bacterial protein-conducting channels PNAS, April 1, 2003; 100(7): 4221 - 4226. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Benach, Y.-T. Chou, J. J. Fak, A. Itkin, D. D. Nicolae, P. C. Smith, G. Wittrock, D. L. Floyd, C. M. Golsaz, L. M. Gierasch, et al. Phospholipid-induced Monomerization and Signal-peptide-induced Oligomerization of SecA J. Biol. Chem., January 31, 2003; 278(6): 3628 - 3638. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y.-T. Chou, J. F. Swain, and L. M. Gierasch Functionally Significant Mobile Regions of Escherichia coli SecA ATPase Identified by NMR J. Biol. Chem., December 20, 2002; 277(52): 50985 - 50990. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. F. Hunt, S. Weinkauf, L. Henry, J. J. Fak, P. McNicholas, D. B. Oliver, and J. Deisenhofer Nucleotide Control of Interdomain Interactions in the Conformational Reaction Cycle of SecA Science, September 20, 2002; 297(5589): 2018 - 2026. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. A. Hobart, S. Ilin, D. F. Moriarty, R. Osuna, and W. Colon Equilibrium denaturation studies of the Escherichia coli factor for inversion stimulation: Implications for in vivo function Protein Sci., July 1, 2002; 11(7): 1671 - 1680. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |