Dissecting the Oxidative Folding of Circular Cystine Knot Miniproteins
Dissecting the Oxidative Folding of Circular Cystine Knot Miniproteins
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DOI：
10.1089/ars.2008.2295
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发表时间：
2009-05-01
影响因子：
6.6
通讯作者：
Craik, David J.
中科院分区：
文献类型：
--
作者：
Gunasekera, Sunithi;Daly, Norelle L.;Craik, David J.
环肽是一种具有特殊稳定性的植物蛋白，因为它存在环状骨架和排列在胱氨酸结基序中的三个二硫键。因此，它们已被提出作为模板，以稳定药物设计应用中的生物活性表位。两个主要的亚家族，称为莫比乌斯和手镯环肽，需要显着不同的体外折叠条件，以实现天然折叠。为了确定影响cyclotide折叠的基本元素，我们研究了一套混合cyclotide的体外折叠的基础上组合的Mobius cyclotide kalata B1和手镯cyclotide cycloviolacin O 1。两个环肽亚家族的折叠途径被发现是不同的，并受到半胱氨酸间环2和6内的特定残基的影响。在这些循环中的两个变化，在循环2中的取代和在循环6中的添加，使折叠的条件下，折叠不会发生在体外的天然肽的环紫素O 1类似物的折叠。一个关键的中间体包含一个天然的发夹结构，似乎是在折叠过程的早期成核位点。总体而言，这些关于环肽类化合物折叠的机制研究结果对于新药先导物的设计具有潜在的价值。抗氧化剂。氧化还原信号。11，971-980。
Cyclotides are plant proteins with exceptional stability owing to the presence of a cyclic backbone and three disulfide bonds arranged in a cystine knot motif. Accordingly, they have been proposed as templates to stabilize bioactive epitopes in drug-design applications. The two main subfamilies, referred to as the Mobius and bracelet cyclotides, require dramatically different in vitro folding conditions to achieve the native fold. To determine the underlying elements that influence cyclotide folding, we examined the in vitro folding of a suite of hybrid cyclotides based on combination of the Mobius cyclotide kalata B1 and the bracelet cyclotide cycloviolacin O1. The folding pathways of the two cyclotide subfamilies were found to be different and influenced by specific residues within intercysteine loops 2 and 6. Two changes in these loops, a substitution in loop 2 and an addition in loop 6, enabled the folding of a cycloviolacin O1 analogue under conditions in which folding does not occur in vitro for the native peptide. A key intermediate contains a native-like hairpin structure that appears to be a nucleation locus early in the folding process. Overall, these mechanistic findings on the folding of cyclotides are potentially valuable for the design of new drug leads. Antioxid. Redox Signal. 11, 971-980.