Substitution of cysteine for glycine-alpha 1-691 in the pro alpha 1(I) chain of type I procollagen in a proband with lethal osteogenesis imperfecta destabilizes the triple helix at a site C-terminal to the substitution.
Substitution of cysteine for glycine-alpha 1-691 in the pro alpha 1(I) chain of type I procollagen in a proband with lethal osteogenesis imperfecta destabilizes the triple helix at a site C-terminal to the substitution.
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在患有致死性成骨不全的先证者中，用半胱氨酸取代 I 型原胶原原 α 1(I) 链中的甘氨酸-α 1-691 会破坏取代位点 C 端三螺旋的稳定性。
DOI：
10.1042/bj2790747
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Prockop,DJ
中科院分区：
文献类型：
--
作者：
Steinmann,B;Westerhausen,A;Constantinou,CD;Superti-Furga,A;Prockop,DJ
皮肤成纤维细胞从先证者与致命的成骨细胞合成一个I型前胶原含有半胱氨酸残基的α 1（I）螺旋结构域。通过蛋白酶消化的三螺旋的热稳定性测定表明，蛋白质的热去折叠的温度降低。特别重要的是观察到通过蛋白酶消化的热稳定性测定显示约140和70 kDa的两个条带以2：1的比例存在; 140 kDa条带可还原为70 kDa条带。对片段的进一步分析表明，半胱氨酸突变产生了残基700周围三螺旋的局部解折叠，并明显暴露了α 1（I）和α 2（I）链中704位的精氨酸残基。cDNA和基因组DNA的分析证明了一个单碱基突变，该突变将α 1（I）链甘氨酸-691的GGT密码子改变为半胱氨酸的TGT密码子。在先证者父母的DNA中没有发现这种突变。由于螺旋稳定性的蛋白酶测定产生了700个残基的片段，其保留在α 1-691处的二硫键键合的半胱氨酸残基，因此结果提供了第一个迹象之一，即I型前胶原中的甘氨酸取代可以改变三螺旋在取代位点C-末端的构象。
Skin fibroblasts from a proband with lethal osteogenesis imperfecta synthesized a type I procollagen containing a cysteine residue in the alpha 1(I) helical domain. Assay of thermal stability of the triple helix by proteinase digestion demonstrated a decreased temperature for thermal unfolding of the protein. Of special importance was the observation that assays of thermal stability by proteinase digestion revealed two bands present in a 2:1 ratio of about 140 and 70 kDa; the 140 kDa band was reducible to a 70 kDa band. Further analysis of the fragments demonstrated that the cysteine mutation produced a local unfolding of the triple helix around residue 700 and apparently exposed the arginine residue at position 704 in both the alpha 1(I) and alpha 2(I) chains. Analysis of cDNAs and genomic DNAs demonstrated a single-base mutation that changed the GGT codon for glycine-691 of the alpha 1(I) chain to a TGT codon for cysteine. The mutation was not found in DNA from either of the proband's parents. Since the proteinase assay of helical stability generated a fragment of 700 residues that retained disulphide-bonded cysteine residues at alpha 1-691, the results provide one of the first indications that glycine substitutions in type I procollagen can alter the conformation of the triple helix at a site that is C-terminal to the site of the substitution.