PDF(Pubmed)
Abstract：
Marfan syndrome, an autosomal dominant disorder of connective tissue, is primarily caused by mutations in the fibrillin-1 (FBN1) gene, which encodes the protein fibrillin-1. The protein is composed of epidermal growth factor-like (EGF-like) domains, transforming growth factor beta-binding protein-like (TB) domains, and hybrid (Hyb) domains and is an important component of elastin-related microfibrils in elastic fiber tissue. In this study, we report a cysteine to tyrosine substitution in two different domains of fibrillin-1, both of which cause Marfan syndrome with ocular abnormalities, in two families. Using protease degradation and liquid chromatography-tandem mass spectrometry analyses, we explored the different effects of substitution of cysteine by tyrosine in an EGF-like and a calcium-binding (cb) EGF-like domain on protein stability. The results showed that cysteine mutations in the EGF domain are more likely to result in altered proteolytic sensitivity and thermostability than those in the cbEGF domain. Furthermore, cysteine mutations can lead to new enzymatic sites exposure or hidden canonical cleavage sites. These results indicate the differential clinical phenotypes and molecular pathogenesis of Marfan syndrome caused by cysteine mutations in different fibrillin-1 domains. These results strongly suggest that failure to form disulfide bonds and abnormal proteolysis of fibrillin-1 caused by cysteine mutations may be an important factor underlying the pathogenesis of diseases caused by fibrillin-1 mutations, such as Marfan syndrome.
摘要：
马凡氏综合征,结缔组织的常染色体显性疾病，主要由原纤维蛋白-1（FBN1）基因突变引起，编码原纤维蛋白-1的蛋白质。该蛋白质由表皮生长因子样（EGF样）结构域组成，转化生长因子β结合蛋白样（TB）结构域，和杂合（Hyb）结构域，是弹性纤维组织中与弹性蛋白相关的微纤维的重要组成部分。在这项研究中,我们报道了在纤丝蛋白-1的两个不同结构域中的半胱氨酸被酪氨酸取代，这两个结构域都会导致伴有眼部异常的马凡氏综合征，在两个家庭。使用蛋白酶降解和液相色谱-串联质谱分析，我们探讨了在EGF样结构域和钙结合(cb)EGF样结构域中酪氨酸取代半胱氨酸对蛋白质稳定性的不同影响.结果表明，与cbEGF结构域相比，EGF结构域中的半胱氨酸突变更可能导致蛋白水解敏感性和热稳定性的改变。此外，半胱氨酸突变可导致新的酶位点暴露或隐藏的典型切割位点。这些结果表明由不同纤丝蛋白-1结构域的半胱氨酸突变引起的马凡氏综合征的不同临床表型和分子发病机制。这些结果强烈表明，半胱氨酸突变引起的原纤维蛋白-1的二硫键形成失败和异常蛋白水解可能是原纤维蛋白-1突变引起的疾病发病机理的重要因素。比如马凡氏综合症。
