Stoichiometry of the Calcineurin Regulatory Domain-Calmodulin Complex

Tori B. Dunlap, Hou Fu Guo, Erik C. Cook, Emily Holbrook, Julie Rumi-Masante, Terrence E. Lester, Christopher L. Colbert, Craig W. Vander Kooi, Trevor P. Creamer

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Calcineurin is an essential serine/threonine phosphatase that plays vital roles in neuronal development and function, heart growth, and immune system activation. Calcineurin is unique in that it is the only phosphatase known to be activated by calmodulin in response to increasing intracellular calcium concentrations. Calcium-loaded calmodulin binds to the regulatory domain of calcineurin, resulting in a conformational change that removes an autoinhibitory domain from the active site of the phosphatase. We have determined a 1.95 Å crystal structure of calmodulin bound to a peptide corresponding to its binding region from calcineurin. In contrast to previous structures of this complex, our structure has a stoichiometry of 1:1 and has the canonical collapsed, wraparound conformation observed for many calmodulin-substrate complexes. In addition, we have used size-exclusion chromatography and time-resolved fluorescence to probe the stoichiometry of binding of calmodulin to a construct corresponding to almost the entire regulatory domain from calcineurin, again finding a 1:1 complex. Taken in sum, our data strongly suggest that a single calmodulin protein is necessary and sufficient to bind to and activate each calcineurin enzyme.

Original languageEnglish
Pages (from-to)5779-5790
Number of pages12
JournalBiochemistry
Volume53
Issue number36
DOIs
StatePublished - Sep 16 2014

Bibliographical note

Publisher Copyright:
© 2014 American Chemical Society.

ASJC Scopus subject areas

  • Biochemistry

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