Whiteman P, Downing A K, Handford P A
Sir William Dunn School of Pathology, University of Oxford, UK.
Protein Eng. 1998 Nov;11(11):957-9. doi: 10.1093/protein/11.11.957.
Fibrillin-1 is a modular glycoprotein and a major component of the 10-12 nm microfibrils of the extracellular matrix. Mutations in the fibrillin-1 (FBN 1) gene result in the connective tissue disease the Marfan syndrome (MFS) and related disorders. The calcium binding EGF-like (cbEGF) domain is the predominant structural motif of the protein and >70% of mutations leading to MFS disrupt this domain. A missense mutation which changes a proline to alanine (P1148A) in cbEGF domain 13 has been associated with a number of fibrillin disorders including MFS and Shprintzen-Goldberg syndrome. However, it has also been described as a polymorphism. In this study comparative NMR analyses on wild-type and mutant forms of covalently-linked fibrillin cbEGF domain pairs have been performed to investigate the structural consequences of this substitution. A comparison of the two-dimensional NOESY spectra of the wild-type and mutant forms of cbEGF domains 12 & 13 and cbEGF domains 13 & 14 indicated that the proline to alanine amino acid change does not introduce a significant structural defect into cbEGF domain 13 or the adjacent domains and most likely represents a polymorphism. These results demonstrate how, in the case of a protein with a well defined domain organisation such as fibrillin-1, comparative NMR analyses can be used to substantiate genetic evidence for the polymorphic status of an amino acid.
原纤蛋白-1是一种模块化糖蛋白，也是细胞外基质10 - 12纳米微原纤维的主要成分。原纤蛋白-1（FBN 1）基因的突变会导致结缔组织疾病马方综合征（MFS）及相关病症。钙结合表皮生长因子样（cbEGF）结构域是该蛋白的主要结构基序，超过70%导致MFS的突变会破坏这一结构域。在cbEGF结构域13中，将脯氨酸变为丙氨酸（P1148A）的错义突变与包括MFS和施普林曾-戈德堡综合征在内的多种原纤蛋白病症相关。然而，它也被描述为一种多态性。在本研究中，对共价连接的原纤蛋白cbEGF结构域对的野生型和突变型进行了比较核磁共振分析，以研究这种替代的结构后果。cbEGF结构域12与13以及cbEGF结构域13与14的野生型和突变型的二维核Overhauser效应光谱（NOESY）比较表明，脯氨酸到丙氨酸的氨基酸变化不会给cbEGF结构域13或相邻结构域引入显著的结构缺陷，很可能代表一种多态性。这些结果表明，对于像原纤蛋白-1这样具有明确结构域组织的蛋白质，比较核磁共振分析如何能够用于证实氨基酸多态性状态的遗传证据。
