期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 356, 期 3, 页码 638-650出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2005.11.055
关键词
CadA; NMR; P1-type ATPase; cadmium detoxification; XAS
资金
- NIGMS NIH HHS [GM 42025, R01 GM042025] Funding Source: Medline
In bacteria, PI-type ATPases are responsible for resistance to di- and monovalent toxic heavy metals by taking them out of the cell. These ATPases have a cytoplasmic N terminus comprising metal binding domains defined by a beta alpha beta beta alpha beta fold and a CXXC metal binding motif. To check how the structural properties of the metal binding site in the N terminus can influence the metal specificity of the ATPase, the first structure of a Cd(II)-ATPase N terminus was determined by NMR and its coordination sphere was investigated by X-ray absorption spectroscopy. A novel metal binding environment was found, comprising the two conserved Cys residues of the metal binding motif and a Glu in loop 5. A bioinformatic search identifies an ensemble of highly homologous sequences presumably with the same function. Another group of highly homologous sequences is found which can be referred to as zinc-detoxifying PI-type ATPases with the metal binding pattern DCXXC in the N terminus. Because no carboxylate groups participate in Cu(l) or Ag(l) binding sites, we suggest that the acidic residue plays a key role in the coordination properties of divalent cations, hence conferring a function to the N terminus in the metal specificity of the ATPase. (c) 2005 Elsevier Ltd. All rights reserved.
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