PMID:16242710
| Citation |
Scheuring, J, Braun, N, Nothdurft, L, Stumpf, M, Veenendaal, AK, Kol, S, van der Does, C, Driessen, AJ and Weinkauf, S (2005) The oligomeric distribution of SecYEG is altered by SecA and translocation ligands. J. Mol. Biol. 354:258-71 |
|---|---|
| Abstract |
The multimeric membrane protein complex translocase mediates the transport of preproteins across and integration of membrane proteins into the inner membrane of Escherichia coli. The translocase consists of the peripheral membrane-associated ATPase SecA and the heterotrimeric channel-forming complex consisting of SecY, SecE and SecG. We have investigated the quaternary structure of the SecYEG complex in proteoliposomes. Fluorescence resonance energy transfer demonstrates that SecYEG forms oligomers when embedded in the membrane. Freeze-fracture techniques were used to examine the oligomeric composition under non-translocating and translocating conditions. Our data show that membrane-embedded SecYEG exists in a concentration-dependent equilibrium between monomers, dimers and tetramers, and that dynamic exchange of subunits between oligomers can occur. Remarkably, the formation of dimers and tetramers in the lipid environment is stimulated significantly by membrane insertion of SecA and by the interaction with translocation ligands SecA, preprotein and ATP, suggesting that the active translocation channel consists of multiple SecYEG complexes. |
| Links |
PubMed Online version:10.1016/j.jmb.2005.09.058 |
| Keywords |
Adenosine Triphosphatases/chemistry; Adenosine Triphosphatases/genetics; Adenosine Triphosphatases/metabolism; Adenosine Triphosphate/metabolism; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Cell Membrane/metabolism; Dimerization; Escherichia coli/enzymology; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Fluorescence Resonance Energy Transfer; Ligands; Membrane Proteins/chemistry; Membrane Proteins/genetics; Membrane Proteins/metabolism; Membrane Transport Proteins/chemistry; Membrane Transport Proteins/genetics; Membrane Transport Proteins/metabolism; Protein Transport; Proteolipids/metabolism |
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