The folding nucleus of a fibronectin type III domain is composed of core residues of the immunoglobulin-like fold
The folding nucleus of a fibronectin type III domain is composed of core residues of the immunoglobulin-like fold
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DOI：
10.1006/jmbi.2000.4378
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发表时间：
2001-02-02
影响因子：
5.6
通讯作者：
Clarke, J
中科院分区：
文献类型：
--
作者：
Cota, E;Steward, A;Clarke, J
为了确定稳定 FNfn10（人纤连蛋白的第十个 fnIII 结构域）折叠限速过渡态的接触点，在该结构域的 29 个位置上分析了 42 个突变体。对突变的异常反应意味着 A、B 和 G 链的结构形成无法通过此方法进行评估。在所有分析的残留物中，phi 值都是分数，没有观察到完全结构化的区域。分析表明，β-三明治中心链的疏水残基形成了过渡态相互作用的一个大核心。布朗斯台德分析表明，过渡态氨基酸侧链的稳定能与天然态的氨基酸侧链稳定能相似，约为 40%。该蛋白质通过成核-缩合机制进行折叠，核心内的三级相互作用构成了折叠核。本地交互（轮流和循环）显然不那么重要。与人生腱蛋白 (TNfn3) 的同源结构域进行比较，结果表明 FNfn10 具有更延伸的结构化过渡态，跨越 β-三明治的三个不同“层”。结果支持这样的假设：共同结构核心中的相互作用引导这些域的折叠。 (C) 2001 年学术出版社。
To identify the contacts that stabilise the rate-limiting transition state for folding of FNfn10 (the tenth fnIII domain of human fibronectin), 42 mutants have been analysed at 29 positions across this domain. An anomalous response to mutation means that structure formation in the A, B and G strands cannot be evaluated by this method. in all the residues analysed, phi-values are fractional and no completely structured region is observed. The analysis reveals that hydrophobic residues from the central strands of the beta-sandwich form a large core of interactions in the transition state. Bronsted analysis shows that the stabilisation energy from the amino acid side-chains in the transition state is similar to 40 % of that in the native state. The protein folds by a nucleation-condensation mechanism, and tertiary interactions within the core make up the folding nucleus. Local interactions, in turns and loops, are apparently much less significant. Comparison with an homologous domain from human tenascin (TNfn3), shows that FNfn10 has a more extended, structured transition state spanning three different "layers" of the beta-sandwich. The results support the hypothesis that interactions in the common structural core guide the folding of these domains. (C) 2001 Academic Press.