The P23T cataract mutation causes loss of solubility of folded γD-crystallin
The P23T cataract mutation causes loss of solubility of folded γD-crystallin
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DOI：
10.1016/j.jmb.2004.08.050
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发表时间：
2004-10-15
影响因子：
5.6
通讯作者：
Slingsby, C
中科院分区：
文献类型：
--
作者：
Evans, P;Wyatt, K;Slingsby, C
人类γ D-晶状体蛋白基因的突变与几种类型的先天性白内障有关。特别地，人γ D晶状体蛋白的Pro23至Thr（P23 T）突变与天蓝色、层状、珊瑚状和束状先天性白内障相关。我们已经表达和纯化了野生型人γ D、P23 T和Pro23 to Ser 23（P23 S）突变体。我们的测量结果表明，P23 T的溶解度明显低于野生型人gammaD，而P23 S的溶解度居中。使用同步辐射圆二色性光谱，我们已经确定P23 T突变体具有略微增加的β-折叠含量，这可能归因于由于用能够形成氢键的残基取代Pro23而导致的边缘β-链的延伸。这两个点突变似乎都没有显著降低蛋白质的热稳定性，也没有降低其对盐酸胍诱导的展开的抗性。这些结果表明，不溶性，而不是失去稳定性，是P23 T先天性白内障的主要基础。(C)2004爱思唯尔有限公司保留所有权利。
Mutations in the human gammaD-crystallin gene have been linked to several types of congenital cataracts. In particular, the Pro23 to Thr (P23T) mutation of human gammaD crystallin has been linked to cerulean, lamellar, coralliform, and fasciculiform congenital cataracts. We have expressed and purified wild-type human gammaD, P23T, and the Pro23 to Ser23 (P23S) mutant. Our measurements show that P23T is significantly less soluble than wild-type human gammaD, with P23S having an intermediate solubility. Using synchrotron radiation circular dichroism spectroscopy, we have determined that the P23T mutant has a slightly increased content of beta-sheet, which may be attributed to the extension of an edge beta-strand due to the substitution of Pro23 with a residue able to form hydrogen bonds. Neither of the point mutations appears to have reduced the thermal stability of the protein significantly, nor its resistance to guanidine hydrochloride-induced unfolding. These results suggest that insolubility, rather than loss of stability, is the primary basis for P23T congenital cataracts. (C) 2004 Elsevier Ltd. All rights reserved.