3din
From Proteopedia
Crystal structure of the protein-translocation complex formed by the SecY channel and the SecA ATPase
Structural highlights
FunctionSECA_THEMA Part of the Sec protein translocase complex. Interacts with the SecYEG preprotein conducting channel. Has a central role in coupling the hydrolysis of ATP to the transfer of proteins into and across the cell membrane, serving as an ATP-driven molecular motor driving the stepwise translocation of polypeptide chains across the membrane (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMost proteins are secreted from bacteria by the interaction of the cytoplasmic SecA ATPase with a membrane channel, formed by the heterotrimeric SecY complex. Here we report the crystal structure of SecA bound to the SecY complex, with a maximum resolution of 4.5 angstrom (A), obtained for components from Thermotoga maritima. One copy of SecA in an intermediate state of ATP hydrolysis is bound to one molecule of the SecY complex. Both partners undergo important conformational changes on interaction. The polypeptide-cross-linking domain of SecA makes a large conformational change that could capture the translocation substrate in a 'clamp'. Polypeptide movement through the SecY channel could be achieved by the motion of a 'two-helix finger' of SecA inside the cytoplasmic funnel of SecY, and by the coordinated tightening and widening of SecA's clamp above the SecY pore. SecA binding generates a 'window' at the lateral gate of the SecY channel and it displaces the plug domain, preparing the channel for signal sequence binding and channel opening. Structure of a complex of the ATPase SecA and the protein-translocation channel.,Zimmer J, Nam Y, Rapoport TA Nature. 2008 Oct 16;455(7215):936-43. PMID:18923516[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found See AlsoReferences
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