Sicot F X, Exposito J Y, Masselot M, Garrone R, Deutsch J, Gaill F
INSU CNRS Roscoff, Universite P.M. Curie, Paris, France.
Eur J Biochem. 1997 May 15;246(1):50-8. doi: 10.1111/j.1432-1033.1997.00050.x.
Arenicola marina possesses cuticular and interstitial collagens, which are mostly synthesised by its epidermis. A cDNA library was constructed from the body wall. This annelid cDNA library was screened with a sea-urchin-collagen cDNA probe, and several overlapping clones were isolated. Nucleotide sequencing of these clones revealed an open reading frame of 2052 nucleotides. The translation product exhibits a triple helical domain of 138 Gly-Xaa-Yaa repeats followed by a 269-residue-long C-terminal non-collagenous domain (C-propeptide). The triple helical domain exhibits an imperfection that has been previously described in a peptide produced by cyanogen bromide digestion (CNBr peptide) of A. marina interstitial collagen. This imperfection occurs at the same place in the interstitial collagen of the vestimentiferan Riftia pachyptila. This identifies the clone as coding for the C-terminal part of a fibrillar collagen chain. It was called FAm1alpha, for fibrillar collagen 1alpha chain of A. marina. The non-collagenous domain possesses a structure similar to carboxy-terminal propeptides of fibrillar pro-alpha chains. Only six conserved cysteine residues are observed in A. marina compared with seven or eight in all other known C-propeptides. This provides information on the importance of disulfide bonds in C-propeptide interactions and in the collagen-assembly process. Phylogenetic studies indicate that the fibrillar collagen 1alpha chain of A. marina is homologous to the R. pachyptila interstitial collagen and that the FAm1alpha gene evolved independently from the other alpha-chain genes. Complementary analyses indicate that the vertebrate fibrillar collagen family is composed of two monophyletic subgroups with a specific position of the collagen type-V chains.
沙蠋拥有表皮胶原蛋白和间质胶原蛋白，它们大多由其表皮合成。从体壁构建了一个cDNA文库。用海胆胶原蛋白cDNA探针筛选这个环节动物cDNA文库，分离出了几个重叠克隆。对这些克隆进行核苷酸测序，发现一个2052个核苷酸的开放阅读框。翻译产物表现出一个由138个Gly-Xaa-Yaa重复序列组成的三螺旋结构域，后面跟着一个269个残基长的C端非胶原蛋白结构域（C-前肽）。三螺旋结构域存在一个缺陷，该缺陷先前在沙蠋间质胶原蛋白的溴化氰消化产物（CNBr肽）中已有描述。在巨型管虫厚壳贻贝的间质胶原蛋白中，这个缺陷出现在相同位置。这表明该克隆编码的是纤维状胶原蛋白链的C端部分。它被命名为FAm1alpha，即沙蠋的纤维状胶原蛋白1alpha链。非胶原蛋白结构域具有与纤维状前α链的羧基末端前肽相似的结构。与所有其他已知的C-前肽中的七个或八个相比，在沙蠋中只观察到六个保守的半胱氨酸残基。这提供了有关二硫键在C-前肽相互作用和胶原蛋白组装过程中的重要性的信息。系统发育研究表明，沙蠋的纤维状胶原蛋白1alpha链与厚壳贻贝的间质胶原蛋白同源，并且FAm1alpha基因是从其他α链基因独立进化而来的。补充分析表明，脊椎动物纤维状胶原蛋白家族由两个单系亚组组成，其中V型胶原蛋白链具有特定位置。
