The N-Terminal Domain of Human Centrin 2 Has a Closed Structure, Binds Calcium with a Very Low Affinity, and Plays a Role in the Protein Self-Assembly
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- 作者：Ao Yang ; Simona Miron ; Patricia Duchambon ; Liliane Assairi ; Yves Blouquit ; and Constantin T. Craescu
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：January 24, 2006
- 年：2006
- 卷：45
- 期：3
- 页码：880 - 889
- 全文大小：414K
- 年卷期：v.45,no.3(January 24, 2006)
- ISSN：1520-4995
文摘
Centrins are well-conserved calcium binding proteins from the EF-hand superfamily implicatedin various cellular functions, such as centrosome duplication, DNA repair, and nuclear mRNA export.The intrinsic molecular flexibility and the self-association tendency make difficult the structuralcharacterization of the integral protein. In this paper we report the solution structure, the Ca2+ bindingproperties, and the intermolecular interactions of the N-terminal domain of two human centrin isoforms,HsCen1 and HsCen2. In the absence of Ca2+, the N-terminal construct of HsCen2 revealed a compactcore conformation including four almost antiparallel 
-helices and a short antiparallel 
-sheet, very similarto the apo state structure of other calcium regulatory EF-hand domains. The first 25 residues show ahighly irregular and dynamic structure. The three-dimensional model for the N-terminal domain of HsCen1,based on the high sequence conservation and NMR spectroscopic data, shows very close structuralproperties. Ca2+ titration of the apo-N-terminal domain of HsCen1 and HsCen2, monitored by NMRspectroscopy, revealed a very weak affinity (102-103 M-1), suggesting that the cellular role of this domainis not calcium dependent. Isothermal calorimetric titrations showed that an 18-residue peptide, derivedfrom the N-terminal unstructured fragment, has a significant affinity (~105 M-1) for the isolated C-terminaldomain, suggesting an active role in the self-assembly of centrin molecules.
-helices and a short antiparallel -sheet, very similarto the apo state structure of other calcium regulatory EF-hand domains. The first 25 residues show ahighly irregular and dynamic structure. The three-dimensional model for the N-terminal domain of HsCen1,based on the high sequence conservation and NMR spectroscopic data, shows very close structuralproperties. Ca2+ titration of the apo-N-terminal domain of HsCen1 and HsCen2, monitored by NMRspectroscopy, revealed a very weak affinity (102-103 M-1), suggesting that the cellular role of this domainis not calcium dependent. Isothermal calorimetric titrations showed that an 18-residue peptide, derivedfrom the N-terminal unstructured fragment, has a significant affinity (~105 M-1) for the isolated C-terminaldomain, suggesting an active role in the self-assembly of centrin molecules.