Resolution of Stepwise Cooperativities of Copper Binding by the Homotetrameric Copper-Sensitive Operon Repressor (CsoR): Impact on Structure and Stability.

ABSTRACT: The cooperativity of ligand binding is central to biological regulation and new approaches are needed to quantify these allosteric relationships. Herein, we exploit a suite of mass spectrometry (MS) experiments to provide novel insights into homotropic Cu-binding cooperativity, gas-phase stabilities and conformational ensembles of the D2 -symmetric, homotetrameric copper-sensitive operon repressor (CsoR) as a function of Cu(I) ligation state. Cu(I) binding is overall positively cooperative, but is characterized by distinct ligation state-specific cooperativities. Structural transitions occur upon binding the first and fourth Cu(I) , with the latter occurring with significantly higher cooperativity than previous steps; this results in the formation of a holo-tetramer that is markedly more r

SUBMITTER: Jacobs AD 

PROVIDER: S-EPMC4673887 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature