1SX0

Solution NMR Structure and X-Ray Absorption Analysis of the C-Terminal Zinc-Binding Domain of the SecA ATPase

Summary for 1SX0

• Entry DOI: 10.2210/pdb1sx0/pdb
• Related: 1SX1
• NMR Information: BMRB: 6191
• Descriptor: SecA (1 entity in total)
• Functional Keywords: zinc, metal ion, tetrahedral coordination, no secondary structure, structural zinc coordination, protein transport
• Total number of polymer chains: 1
• Total formula weight: 2425.84

Authors

Dempsey, B.R.,Wrona, M.,Moulin, J.M.,Gloor, G.B.,Jalilehvand, F.,Lajoie, G.,Shaw, G.S.,Shilton, B.H. (deposition date: 2004-03-30, release date: 2004-07-06, Last modification date: 2024-05-22)

Primary citation

Dempsey, B.R.,Wrona, M.,Moulin, J.M.,Gloor, G.B.,Jalilehvand, F.,Lajoie, G.,Shaw, G.S.,Shilton, B.H.
Solution NMR Structure and X-ray Absorption Analysis of the C-Terminal Zinc-Binding Domain of the SecA ATPase.
Biochemistry, 43:9361-9371, 2004

PubMed Abstract: 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.

PubMed: 15260479
DOI: 10.1021/bi0493057

Experimental method

SOLUTION NMR