Xin-repeats and nebulin-like repeats bind to F-actin in a similar manner
Xin-repeats and nebulin-like repeats bind to F-actin in a similar manner
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DOI：
10.1016/j.jmb.2005.11.082
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发表时间：
2006-02-24
影响因子：
5.6
通讯作者：
Egelman, EH
中科院分区：
文献类型：
--
作者：
Cherepanova, O;Orlova, A;Egelman, EH
Xin和nebulette是横纹肌特异性肌动蛋白结合蛋白，都含有多个肌动蛋白结合重复序列。这些重复序列的性质是不同的：nebulette具有类似于nebulin的重复序列，而Xin含有自己独特的重复序列。然而，从生化数据中提出的建议是，Xin重复序列可能与肌动蛋白分子上的多个位点结合，就像在星云蛋白中发现的那样。我们已经使用电子显微镜和迭代螺旋真实的空间重建可视化复合物的F-肌动蛋白与Xin片段含有三个或六个Xin重复，并与CN 5-nebulette片段，含有五个星云蛋白样重复。我们的研究结果表明，Xin和nebellette片段结合F-肌动蛋白以类似的方式，并在两个不同的模式：在一个模式肌动蛋白亚结构域I结合，而在第二种模式的结合桥之间的不同位点的肌动蛋白亚结构域1/2的一个原聚体和亚结构域3/4的相邻的肌动蛋白原聚体。结合已发表的关于星云蛋白、原肌球蛋白和ADF/cofilin的数据，我们的研究结果表明，以多种模式与肌动蛋白原聚体结合的能力是许多肌动蛋白结合蛋白的一般性质。(c)2005爱思唯尔有限公司保留所有权利。
Xin and nebulette are striated muscle-specific actin-binding proteins that both contain multiple actin-binding repeats. The nature of these repeats is different: nebulette has nebulin-like repeats, while Xin contains its own unique repeats. However, the suggestion was made from biochemical data that the Xin-repeats may bind to multiple sites on the actin molecule as was found for nebulin. We have used electron microscopy and the iterative helical real space reconstruction to visualize complexes of F-actin with Xin fragments containing either three or six Xin-repeats, and with the CN5-nebulette fragment, containing five nebulin-like repeats. Our results indicate that Xin and nebulette fragments bind to F-actin in a similar manner and in two distinct modes: in one mode actin subdomain I is bound, while in the second mode the binding bridges between a different site on actin subdomains 1/2 of one protomer and subdomains 3/4 of an adjacent actin protomer. Taken together with published data about nebulin, tropomyosin and ADF/cofilin, our results suggest that the ability to bind in multiple modes to the actin protomer is a general property of many actin-binding proteins. (c) 2005 Elsevier Ltd. All rights reserved.