Steplewski Andrzej, Ito Hidetoshi, Rucker Eileen, Brittingham Raymond J, Alabyeva Tatiana, Gandhi Milind, Ko Frank K, Birk David E, Jimenez Sergio A, Fertala Andrzej
Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
J Struct Biol. 2004 Dec;148(3):326-37. doi: 10.1016/j.jsb.2004.07.006.
Collagen II fibrils are a critical structural component of the extracellular matrix of cartilage providing the tissue with its unique biomechanical properties. The self-assembly of collagen molecules into fibrils is a spontaneous process that depends on site-specific binding between specific domains belonging to interacting molecules. These interactions can be altered by mutations in the COL2A1 gene found in patients with a variety of heritable cartilage disorders known as chondrodysplasias. Employing recombinant procollagen II, we studied the effects of R75C or R789C mutations on fibril formation. We determined that both R75C and R789C mutants were incorporated into collagen assemblies. The effects of the R75C and R789C substitutions on fibril formation differed significantly. The R75C substitution located in the thermolabile region of collagen II had no major effect on the fibril formation process or the morphology of fibrils. In contrast, the R789C substitution located in the thermostable region of collagen II caused profound changes in the morphology of collagen assemblies. These results provide a basis for identifying pathways leading from single amino acid substitutions in collagen II to changes in the structure of individual fibrils and in the organization of collagenous matrices.
Ⅱ型胶原纤维是软骨细胞外基质的关键结构成分，赋予组织独特的生物力学特性。胶原分子自组装成纤维是一个自发过程，依赖于相互作用分子特定结构域之间的位点特异性结合。在多种遗传性软骨疾病（称为软骨发育异常）患者中发现的COL2A1基因突变可改变这些相互作用。利用重组前胶原Ⅱ，我们研究了R75C或R789C突变对纤维形成的影响。我们确定R75C和R789C突变体都能整合到胶原聚集体中。R75C和R789C取代对纤维形成的影响有显著差异。位于Ⅱ型胶原热不稳定区域的R75C取代对纤维形成过程或纤维形态没有重大影响。相比之下，位于Ⅱ型胶原热稳定区域的R789C取代导致胶原聚集体形态发生深刻变化。这些结果为确定从Ⅱ型胶原中的单个氨基酸取代到单个纤维结构和胶原基质组织变化的途径提供了基础。
