1sx0
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Solution NMR Structure and X-Ray Absorption Analysis of the C-Terminal Zinc-Binding Domain of the SecA ATPase
OverviewOverview
The solution NMR structure of a 22-residue Zn(2+)-binding domain (ZBD), from Esherichia coli preprotein translocase subunit SecA is presented. In, conjunction with X-ray absorption analysis, the NMR structure shows that, three cysteines and a histidine in the sequence CXCXSGX(8)CH assume a, tetrahedral arrangement around the Zn(2+) atom, with an average Zn(2+)-S, bond distance of 2.30 A and a Zn(2+)-N bond distance of 2.03 A. The NMR, structure shows that ND1 of His20 binds to the Zn(2+) atom. The ND1-Zn(2+), bond is somewhat strained: it makes an angle of approximately 17 degrees, with the plane of the ring, and it also shows a significant "in-plane", distortion of 13 degrees. A comprehensive sequence alignment of the, SecA-ZBD from many different organisms shows that, along with the four, Zn(2+) ligands, there is a serine residue (Ser12) that is completely, conserved. The NMR structure indicates that the side chain of this serine, residue forms a strong hydrogen bond with the thiolate of the third, cysteine residue (Cys19); therefore, the conserved serine appears to have, a critical role in the structure. SecB, an export-specific chaperone, is, the only known binding partner for the SecA-ZBD. A phylogenetic analysis, using 86 microbial genomes shows that 59 of the organisms carry SecA with, a ZBD, but only 31 of these organisms also possess a gene for SecB, indicating that there may be uncharacterized binding partners for the, SecA-ZBD.
About this StructureAbout this Structure
1SX0 is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
ReferenceReference
Solution NMR structure and X-ray absorption analysis of the C-terminal zinc-binding domain of the SecA ATPase., Dempsey BR, Wrona M, Moulin JM, Gloor GB, Jalilehvand F, Lajoie G, Shaw GS, Shilton BH, Biochemistry. 2004 Jul 27;43(29):9361-71. PMID:15260479
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