Structure of the N-terminal calcium sensor domain of centrin reveals the biochemical basis for domain-specific function.

Sheehan JH, Bunick CG, Hu H, Fagan PA, Meyn SM, Chazin WJ
J Biol Chem. 2006 281 (5): 2876-81

PMID: 16317001 · DOI:10.1074/jbc.M509886200

Centrin is an essential component of microtubule-organizing centers in organisms ranging from algae and yeast to humans. It is an EF-hand calcium-binding protein with homology to calmodulin but distinct calcium binding properties. In a previously proposed model, the C-terminal domain of centrin serves as a constitutive anchor to target proteins, and the N-terminal domain serves as the sensor of calcium signals. The three-dimensional structure of the N-terminal domain of Chlamydomonas rheinhardtii centrin has been determined in the presence of calcium by solution NMR spectroscopy. The domain is found to occupy an open conformation typical of EF-hand calcium sensors. Comparison of the N- and C-terminal domains of centrin reveals a structural and biochemical basis for the domain specificity of interactions with its cellular targets and the distinct nature of centrin relative to other EF-hand proteins. An NMR titration of the centrin N-terminal domain with a fragment of the known centrin target Sfi1 reveals binding of the peptide to a discrete site on the protein, which supports the proposal that the N-terminal domain serves as a calcium sensor in centrin.

MeSH Terms (11)

Animals Binding Sites Calcium-Binding Proteins Calcium Signaling Chlamydomonas reinhardtii Chromosomal Proteins, Non-Histone EF Hand Motifs Magnetic Resonance Spectroscopy Protein Conformation Solutions Titrimetry

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