2ipc | pdb_00002ipc

Crystal structure of the translocation ATPase SecA from Thermus thermophilus reveals a parallel, head-to-head dimer

spinqualitylabelsall models 2ipc, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2ipc is a 4 chain structure with sequence from Thet8. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Gene: SecA (THET8) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT, TOPSAN Function [SECA_THET8] 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.[HAMAP-Rule:MF_01382] 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 PubMed The mechanism of pre-protein export through the bacterial cytoplasmic membrane, in which the SecA ATPase plays a crucial role as an "energy supplier", is poorly understood. In particular, biochemical and structural studies provide contradictory data as to the oligomeric state of SecA when it is integrated into the active trans-membrane translocase. Here, we report the 2.8 A resolution crystal structure of the Thermus thermophilus SecA protein (TtSecA). Whereas the structure of the TtSecA monomer closely resembles that from other bacteria, the oligomeric state of TtSecA is strikingly distinct. In contrast to the antiparallel (head-to-tail) dimerization reported previously for the other bacterial systems, TtSecA forms parallel (head-to-head) dimers that are reminiscent of open scissors. The dimer interface is abundant in bulky Arg and Lys side-chains from both subunits, which stack on one another to form an unusual "basic zipper" that is highly conserved, as revealed by homology modeling and sequence analysis. The basic zipper is sealed on both ends by two pairs of the salt bridges formed between the basic side-chains from the zipper and two invariant acidic residues. The organization of the dimers, in which the two pre-protein binding domains are located proximal to each other at the tip of the "scissors", might allow a concerted mode of substrate recognition while the opening/closing of the scissors might facilitate translocation. Crystal structure of the translocation ATPase SecA from Thermus thermophilus reveals a parallel, head-to-head dimer.,Vassylyev DG, Mori H, Vassylyeva MN, Tsukazaki T, Kimura Y, Tahirov TH, Ito K J Mol Biol. 2006 Dec 1;364(3):248-58. Epub 2006 Sep 29. PMID:17059823 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Preprotein translocase SecA

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