Specific recognition of the collagen triple helix by chaperone HSP47 - Minimal structural requirement and spatial molecular orientation
Specific recognition of the collagen triple helix by chaperone HSP47 - Minimal structural requirement and spatial molecular orientation
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DOI：
10.1074/jbc.m509707200
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发表时间：
2006-02-10
影响因子：
4.8
通讯作者：
Kitagawa, K
中科院分区：
文献类型：
--
作者：
Koide, T;Asada, S;Kitagawa, K
在内质网中独特的前胶原折叠是在前胶原特异性分子伴侣的帮助下实现的。热休克蛋白47 （HSP47）是一种内质网内的伴侣蛋白，在正常的前胶原折叠中起重要作用，尽管其分子功能尚未明确。最近关于HSP47结合特异性的研究进展表明，胶原Gly-Xaa-Yaa重复序列中Yaa位置的Arg残基对其相互作用至关重要(Koide， T., Takahara， Y., Asada， S., and Nagata， K.（2002）。化学学报，2007,26 (6):678 -6182；Tasab， M., Jenkinson， L., and bullid, n.j.（2002）。化学，277,35007-35012)。在本研究中，我们利用工程胶原模型肽的系统进一步研究了HSP47的客户识别机制。首先，利用构象受限的胶原样肽进行的体外结合研究表明，HSP47只识别正确折叠的三螺旋，与相应的单链多肽的相互作用可以忽略不计。其次，利用异三聚体模型客户端对HSP47的结合研究表明，三螺旋结构中Arg残基的数量要求最低。最后，一项使用光反应性胶原肽的交联研究提供了关于伴侣-胶原复合物中HSP47分子空间取向的信息。获得的结果导致hsp47 -胶原复合物的新模型的发展，完全不同于先前提出的“飞盘模型”(Dafforn， T. R., Della， M., and Miller, a . D. (2001) J. Biol。化学，276,49310-49319)。
The unique folding of procollagens in the endoplasmic reticulum is achieved with the assistance of procollagen-specific molecular chaperones. Heat-shock protein 47 (HSP47) is an endoplasmic reticulum-resident chaperone that plays an essential role in normal procollagen folding, although its molecular function has not yet been clarified. Recent advances in studies on the binding specificity of HSP47 have revealed that Arg residues at Yaa positions in collagenous Gly-Xaa-Yaa repeats are critical for its interactions (Koide, T., Takahara, Y., Asada, S., and Nagata, K. (2002) J. Biol. Chem. 277, 6178-6182; Tasab, M., Jenkinson, L., and Bulleid, N. J. (2002) J. Biol. Chem. 277, 35007-35012). In the present study, we further examined the client recognition mechanism of HSP47 by taking advantage of systems employing engineered collagen model peptides. First, in vitro binding studies using conformationally constrained collagen-like peptides revealed that HSP47 only recognized correctly folded triple helices and that the interaction with the corresponding single-chain polypeptides was negligible. Second, a binding study using heterotrimeric model clients for HSP47 demonstrated a minimal requirement for the number of Arg residues in the triple helix. Finally, a cross-linking study using photoreactive collagenous peptides provided information about the spatial orientation of an HSP47 molecule in the chaperone-collagen complex. The obtained results led to the development of a new model of HSP47-collagen complexes that differs completely from the previously proposed "flying capstan model" (Dafforn, T. R., Della, M., and Miller, A. D. ( 2001) J. Biol. Chem. 276, 49310-49319).