A large conformational change of the translocation ATPase SecA.

Osborne, Andrew R; Clemons, William M; Rapoport, Tom A · Proc Natl Acad Sci U S A · 2004

basic_science · Level V

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Abstract

The ATPase SecA mediates the posttranslational translocation of a wide range of polypeptide substrates through the SecY channel in the cytoplasmic membrane of bacteria. We have determined the crystal structure of a monomeric form of Bacillus subtilis SecA at a 2.2-A resolution. A comparison with the previously determined structures of SecA reveals a nucleotide-independent, large conformational change that opens a deep groove similar to that in other proteins that interact with diverse polypeptides. We propose that the open form of SecA represents an activated state.

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