2fsh | pdb_00002fsh
Complex SecA:AMP-PNP from Escherichia coli
Structural highlights
Function[SECA_ECOLI] Required for protein export, interacts with the SecYEG preprotein conducting channel. SecA has a central role in coupling the hydrolysis of ATP to the transfer of proteins into and across the cell membrane, serving both as a receptor for the preprotein-SecB complex and as an ATP-driven molecular motor driving the stepwise translocation of polypeptide chains across the membrane.[1] 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 PubMedSecA is the preprotein translocase ATPase subunit and a superfamily 2 (SF2) RNA helicase. Here we present the 2 A crystal structures of the Escherichia coli SecA homodimer in the apo form and in complex with ATP, ADP and adenosine 5'-[beta,gamma-imido]triphosphate (AMP-PNP). Each monomer contains the SF2 ATPase core (DEAD motor) built of two domains (nucleotide binding domain, NBD and intramolecular regulator of ATPase 2, IRA2), the preprotein binding domain (PBD), which is inserted in NBD and a carboxy-terminal domain (C-domain) linked to IRA2. The structures of the nucleotide complexes of SecA identify an interfacial nucleotide-binding cleft located between the two DEAD motor domains and residues critical for ATP catalysis. The dimer comprises two virtually identical protomers associating in an antiparallel fashion. Dimerization is mediated solely through extensive contacts of the DEAD motor domains leaving the C-domain facing outwards from the dimerization core. This dimerization mode explains the effect of functionally important mutations and is completely different from the dimerization models proposed for other SecA structures. The repercussion of these findings on translocase assembly and catalysis is discussed. Structure of dimeric SecA, the Escherichia coli preprotein translocase motor.,Papanikolau Y, Papadovasilaki M, Ravelli RB, McCarthy AA, Cusack S, Economou A, Petratos K J Mol Biol. 2007 Mar 9;366(5):1545-57. Epub 2006 Dec 23. PMID:17229438[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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