A Single Approach Reveals the Composite Conformational Changes, Order of Binding, and Affinities for Calcium Binding to Calmodulin.

ABSTRACT: We found that a newly developed method named LITPOMS (ligand titration, fast photochemical oxidation of proteins and mass spectrometry) can characterize section-by-section of a protein the conformational changes induced by metal-ion binding. Peptide-level LITPOMS applied to Ca²⁺ binding to calmodulin reveals binding order and site-specific affinity, providing new insights on the behavior of proteins upon binding Ca²⁺. We established that EF hand-4 (EF-4) binds calcium first, followed by EF-3, EF-2, and EF-1 and determined the four affinity constants by modeling the extent-of-modification curves. We also found positive cooperativity between EF-4, EF-3 and EF-2, EF-1 and allostery involving the four EF-hands. LITPOMS recapitulates via one approach the calcium-calmodulin

SUBMITTER: Liu XR 

PROVIDER: S-EPMC6506365 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature