Reactive cysteine in the structural Zn(2+) site of the C1B domain from PKCα.

ABSTRACT: Structural cysteine-rich Zn(2+) sites that stabilize protein folds are considered to be unreactive. In this article, we identified a reactive cysteine residue, Cys151, in a treble-clef zinc finger with a Cys(3)His coordination sphere. The protein in question is the C1B domain of Protein Kinase Cα (PKCα). Mass-tagging cysteine assays of several C1B variants were employed to ascertain the site specificity of the covalent modification. The reactivity of Cys151 in C1B also manifests itself in the structural dynamics of the Zn(2+) coordination sphere where the Sγ of Cys151 alternates between the Zn(2+)-bound thiolate and free thiol states. We used NMR-detected pH titrations, ZZ-exchange spectroscopy, and residual dipolar coupling (RDC)-driven structure refinement to characterize the two exchang

SUBMITTER: Stewart MD 

PROVIDER: S-EPMC3645944 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature