Role of the pro-α2(I) COOH-terminal region in assembly of type I collagen: Disruption of two intramolecular disulfide bonds in pro-α2(I) blocks assembly of type I collagen

✍ Scribed by Sharon A. Doyle; Barbara D. Smith

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 141 KB
• Volume: 71
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/(sici)1097-4644(19981101)71:2<233::aid-jcb8>3.0.co;2-w

✦ Synopsis

Collagen biosynthesis is a complex process that begins with the association of three procollagen chains. A series of conserved intra-and interchain disulfide bonds in the carboxyl-terminal region of the procollagen chains, or C-propeptide, has been hypothesized to play an important role in the nucleation and alignment of the chains. We tested this hypothesis by analyzing the ability of normal and cysteine-mutated pro-␣2(I) chains to assemble into type I collagen heterotrimers when expressed in a cell line (D2) that produces only endogenous pro-␣1(I). Pro-␣2(I) chains containing single or double cysteine mutations that disrupted individual intra-or interchain disulfide bonds were able to form pepsin resistant type I collagen with pro-␣1(I), indicating that individual disulfide bonds were not critical for assembly of the pro-␣2(I) chain with pro-␣1(I). Pro-␣2(I) chains containing a triple cysteine mutation that disrupted both intrachain disulfide bonds were not able to form pepsin resistant type I collagen with pro-␣1(I). Therefore, disruption of both pro-␣2(I) intrachain disulfide bonds prevented the production and secretion of type I collagen heterotrimers. Although none of the individual disulfide bonds is essential for assembly of the procollagen chains, the presence of at least one intrachain disulfide bond may be necessary as a structural requirement for chain association or to stabilize the protein to prevent intracellular degradation.