N-Terminal Aliphatic Residues Dictate the Structure, Stability, Assembly, and Small Molecule Binding of the Coiled-Coil Region of Cartilage Oligomeric Matrix Protein
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- 作者：Susheel K. Gunasekar ; Mukta Asnani ; Chandani Limbad ; Jennifer S. Haghpanah ; Wendy Hom ; Hanna Barra ; Soumya Nanda ; Min Lu ; Jin Kim Montclare
- 刊名：Biochemistry
- 出版年：2009
- 出版时间：September 15, 2009
- 年：2009
- 卷：48
- 期：36
- 页码：8559-8567
- 全文大小：880K
- 年卷期：v.48,no.36(September 15, 2009)
- ISSN：1520-4995
文摘
The coiled-coil domain of cartilage oligomeric matrix protein (COMPcc) assembles into a homopentamer that naturally recognizes the small molecule 1,25-dihydroxyvitamin D3 (vit D). To identify the residues critical for the structure, stability, oligomerization, and binding to vit D as well as two other small molecules, all-trans-retinol (ATR) and curcumin (CCM), here we perform an alanine scanning mutagenesis study. Ten residues lining the hydrophobic pocket of COMPcc were mutated into alanine; of the mutated residues, the N-terminal aliphatic residues L37, L44, V47, and L51 are responsible for maintaining the structure and function. Furthermore, two polar residues, T40 and Q54, within the N-terminal region when converted into alanine improve the α-helical structure, stability, and self-assembly behavior. Helical stability, oligomerization, and binding appear to be linked in a manner in which mutations that abolish helical structure and assembly bind poorly to vit D, ATR, and CCM. These results provide not only insight into COMPcc and its functional role but also useful guidelines for the design of stable, pentameric coiled-coils capable of selectively storing and delivering various small molecules.