Site Specific Interactions and Collagen Self Assembly

蛋白质自组装成大分子的能力是所有活着的有机体的基础。其中一些最复杂的结构是由三股螺旋胶原蛋白形成的纤维。单体自组装成纤维的确切方式还没有定义。目前的应用是基于我们的观察，即I型胶原的端肽结合到Alpha1(1)链的776到822个氨基酸的特定区域，并且这种相互作用对胶原的自组装至关重要。我们最近对I型和II型胶原突变体的组装结果有力地支持了我们的假设，即胶原分子之间的位置特异性相互作用对纤维的形成至关重要。我们现在使用基因工程的II型和IX型胶原来详细研究同型和异型纤维的形成机制。该项目的长期目标是了解胶原纤维在健康和疾病中形成的基本原理。总的假设是，在纤维组装过程中，胶原单体之间的特异性相互作用是由端肽与三螺旋结构域的特定区域结合控制的。这种结合对胶原纤维的形成起着至关重要的调节作用。此外，我们假设异型纤维的组装也受部位特异性形成的控制。此外，我们假设异型纤维的组装也受不同类型胶原之间的部位特异性相互作用控制，纤维胶原的突变改变了部位特异性的相互作用，从而改变了细胞外基质的结构。为了验证这些假说，我们提出了以下具体目标：(1)阐明同型和异型胶原纤维形成的部位特异性机制；(2)确定胶原分子之间的部位特异性相互作用如何调节纤维的形态、胶原自组装的动力学和热力学；(3)分析胶原纤维中的突变如何影响胶原组装的部位特异性机制。这项拟议的研究将为胶原纤维的胶原自组装结构提供新的信息。所提出的研究结果将在胶原纤维发挥重要作用的领域有广泛的应用。例如，细胞分化和增殖、发育、骨矿化、组织重塑、纤维化、组织工程学和结缔组织遗传病的治疗。

The ability of proteins to self-assemble into macromolecules is fundamental to all living organisms. Some of the most complex of these structures are the fibrils formed from the triple helical collagen. The precise manner in which the monomers self-assemble into fibrils has not been defined. The present application is based on our observations that the telopeptides of collagen I bind to a specific region spanning amino acids 776 to 822 of the alpha1(1) chain, and that this interaction is critical for collagen self-assembly. Our recent results of the assembly of collagen I and collagen II mutants, strongly support our hypothesis that site-specific interactions between collagen molecules are critical for the fibril formation. We now use the gene-engineered collagen II and collagen IX to study the mechanism of the formation of homotypic and heterotypic fibrils in detail. The broad, long-term goal of this project is to understand fundamental principles of the formation of collagen fibrils in health and disease. The overall hypothesis is that the specific interaction between collagen monomers during fibril assembly is controlled by the binding of telopeptides to specific regions of the triple- helical domain. This binding is critical for the regulation of collagen fibril formation. Moreover, we hypothesize that assembly of heterotypic fibrils is also controlled by the site-specific formation. Moreover we hypothesize that assembly of heterotypic fibrils is also controlled by the site-specific interactions between different collagen types, and that mutations in fibrillar collagens change the site-specific interaction and, as a result, alter the structure of the extracellular matrix. To test the hypotheses, the following specific aims are proposed: (1) To elucidate a site-specific mechanism of the formation of homotypic and heterotypic collagen fibrils, (2) To determine how the site-specific interactions between collagen molecules regulate morphology of fibrils, kinetics and thermodynamics of collagen self-assembly, and (3) To analyze how mutations in fibrillar collagens affect the site-specific mechanism of collagen assembly. The proposed research will yield new information on collagen self-assembly structure of collagen fibrils. Results of the proposed studies will have a wide application in the areas where collagen fibrils play an important role. Examples include cell differentiations and proliferations, development, bone mineralization, tissue remodeling, fibrosis, tissue engineering, and therapy of the heritable diseases of connective tissue.