title: Structure of the N-terminal calcium sensor domain of centrin reveals the biochemical basis for domain-specific function.
abstract: 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.
authors.affiliation: Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232-8725, USA.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Sheehan
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Bunick
authors.forename: Haitao
authors.initials: H
authors.lastname: Hu
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Fagan
authors.forename: Susan M
authors.initials: SM
authors.lastname: Meyn
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Chazin
mesh_terms: D000818:Animals; D001665:Binding Sites; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000502:physiology; D016825:Chlamydomonas reinhardtii / Q000737:chemistry*; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000502:physiology; D020832:EF Hand Motifs; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D012996:Solutions; D017186:Titrimetry
chemical_list: D002135:Calcium-Binding Proteins; D002868:Chromosomal Proteins, Non-Histone; D012996:Solutions; C056608:caltractin