Mechanism of Cu+-transporting ATPases: Soluble Cu+ chaperones directly transfer Cu+ to transmembrane transport sites

作者：Gonzalez Guerrero Manuel; Argueello Jose M

来源：Proceedings of the National Academy of Sciences, 2008, 105(16): 5992-5997.

DOI：10.1073/pnas.0711446105

• CopA
• CopZ
• Cu homeostasis
• Cu-ATPase
• metal binding

As in other P-type ATPases, metal binding to transmembrane metal-binding sites (TIMI-MBS) in Cu+-ATPases is required for enzyme phosphorylation and subsequent transport. However, Cu+ does not access Cu+-ATPases in a free (hydrated) form but is bound to a chaperone protein. Cu+ transfer from Cu+ chaperones to regulatory cytoplasmic metal-binding domains (MBDs) present in these ATPases has been described, but there is no evidence of a proposed subsequent Cu+ movement from the MBDs to the TM-MIBS. Alternatively, we postulate the parsimonious Cu+ transfer by the chaperone directly to TM-MBS. Testing both models, the delivery of Cu+ by Archaeoglobus fulgidus Cu+ chaperone CopZ to the corresponding Cu+-ATPase, CopA, was studied. As expected, CopZ interacted with and delivered the metal to CopA MBDs. Cu+-loaded MBDs, acting as metal donors, were unable to activate CopA or a truncated CopA lacking MBDs. Conversely, Cu+-loaded CopZ activated the CopA ATIPase and CopA constructs in which MBDs were rendered unable to bind Cu+. Furthermore, under nonturnover conditions, CopZ transferred Cu+ to the TM-MBS of a CopA lacking MBDs. These data are consistent with a model where MBDs serve a regulatory function without participating in metal transport and the chaperone delivers Cu+ directly to transmembrane transport sites of Cu+-ATPases.

• 出版日期2008-4-22