Requirement of carbon dioxide for in vitro assembly of the urease nickel metallocenter.
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Park IS, Hausinger RP
Requirement of carbon dioxide for in vitro assembly of the urease nickel metallocenter.
Science. 1995 Feb 24;267(5201):1156-8.
- PubMed ID
- 7855593 [ View in PubMed]
- Abstract
Assembly of protein metallocenters is not well understood. Urease offers a tractable system for examination of this process. Formation of the urease metallocenter in vivo is known to require four accessory proteins: UreD, postulated to be a urease-specific molecular chaperone; UreE, a nickel(II)-binding protein; and UreF and UreG, of unknown function. Activation of purified Klebsiella aerogenes urease apoprotein was accomplished in vitro by providing carbon dioxide (half-maximal activation at approximately 0.2 percent carbon dioxide) in addition to nickel ion. Activation coincided with carbon dioxide incorporation into urease in a pH-dependent reaction (pKa > or = 9, where Ka is the acid constant). The concentration of carbon dioxide also affected the amount of activation of UreD-urease apoprotein complexes. These results suggest that carbon dioxide binding to urease apoprotein generates a ligand that facilitates productive nickel binding.