波谱学杂志 ›› 2010, Vol. 27 ›› Issue (4): 584-596.

• 恭贺沈联芳和杜有如两位先生八十华诞专栏 • 上一篇    下一篇

应用15N-1H残留偶极偶合验证刪除肝癌2(DLC2-SAM)不育-α-基序域的螺旋间的取向

李洪艳*, 时港洪, 冯景梁,孙红哲*   

  1. 香港大学 化学系,香港薄扶林道
  • 收稿日期:2010-10-19 修回日期:2010-10-26 出版日期:2010-12-05 发布日期:2010-12-05
  • 基金资助:

    Research Grants Council of Hong Kong, Croucher Foundation and the University of Hong Kong development fund (UDF).

Validation of Inter-Helical Orientation of the Sterile-α-Motif Domain of the Deleted in Liver Cancer 2 (DLC2-SAM) by 15N-1H Residual Dipolar Couplings

 LI Hong-Yan*, SZE Kong-Hung, FUNG King-Leung, SUN Gong-Zhe*   

  1. Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong,  China
  • Received:2010-10-19 Revised:2010-10-26 Online:2010-12-05 Published:2010-12-05
  • Supported by:

    Research Grants Council of Hong Kong, Croucher Foundation and the University of Hong Kong development fund (UDF).

摘要:

刪除肝癌2 (DLC2), 一种经常发现在原发性肝癌过低表达的肿瘤抑制基因, 编码一种含有不育-α-基序多域蛋白质(DLC2-SAM). 以前SAM域蛋白 (DLC2-SAM) 核磁共振结构显示此蛋白是由独特的四螺旋束组成,与其它已知SAM域结构截然不同. 在该研究中,作者运用了15N-1H残留偶极偶合 (RDC)作为附加约束连同NOE和TALOS数据进一步优化了DLC2-SAM 的结构. 由此所得的结构与没有15N-1H残留偶 极偶合约束比较显示改善了结构的质量 并且有较低的Q值. 螺旋的取向,尤其是螺旋4,被残留偶极偶合数据所验证. RDC-优化的人类DLC2-SAM的结构与小鼠的DLC2-SAM很相像. DLC家庭独特的SAM域结构表明该域可能还具有没被发现的新功能.

关键词: 核磁共振(NMR), DLC2, 残留偶极偶合, SAM 域, 结构优化

Abstract:

The deleted in liver cancer 2 (DLC2), a tumor suppression gene which is frequently found to be underexpressed in hepatocellular carcinoma, encodes a multi-domain protein comprising a sterile- α-motif domain (DLC2-SAM). Previous NMR structural studies of the SAM domain protein (DLC2-SAM) revealed a unique four helical bundle structure, distinct from any other known SAM domain structures.  In the present study, we have applied 15N-1H residual dipolar couplings as additional constraints to refining the solution structures of the DLC2-SAM together with nuclear Overhauser enhancement and TALOS data. The resulting structures show improved quality factors when comparing with the structures derived without RDC constraints and have a lower Q factor. Orientations of the helices, in particular the helix 4, are validated by residual dipolar coupling data. Our RDC-refined human DLC2-SAM structures resemble those of murine DLC2-SAM. The unique structures of the SAM domain from DLC family implicate that the SAM domain may serve novel functions although these have not yet been unveiled.

Key words: NMR spectroscopy, DLC2, residual dipolar coupling, SAM domain, structure refinement

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