Structural effects of cofilin on longitudinal contacts in F-actin
Structural effects of cofilin on longitudinal contacts in F-actin
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DOI：
10.1016/s0022-2836(02)01008-2
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发表时间：
2002-11-01
影响因子：
5.6
通讯作者：
Reisler, E
中科院分区：
文献类型：
--
作者：
Bobkov, AA;Muhlrad, A;Reisler, E
研究了酵母cofilin对骨骼肌和酵母肌动蛋白的结构影响。Cofilin与天然肌动蛋白的结合是非合作的，以1:1的摩尔比饱和，CaATP-G-actin和F-actin的K-d均小于或等于0.05 muM。Cofilin结合增强了dansyl乙二胺（DED）附着在骨骼肌f -肌动蛋白DNase I结合环Gln41上的荧光，降低了AEDANS在酵母Q41C/C374S突变体f -肌动蛋白Cys41上的荧光。而cofilin对CaATP-G-actin上DED或AEDANS的光谱性质没有影响。从色氨酸残基到骨骼肌肌动蛋白Gln41位点DED和酵母Q41C/ C374S肌动蛋白Cys41位点AEDANS的荧光能量转移（FRET）由于cofilin与F-结合而没有与g -肌动蛋白结合而减少。Cofilin强烈抑制Cys41蛋白间二硫交联的速率。酵母Q41C突变体F-actin上的Cys374。cofilin的结合增强了Q41C F-actin上连接Cys41和Cys374的芘探针之间的准分子形成。这些结果表明，cofilin改变了子结构域I和子结构域2之间的界面，并将DNase I结合环从相邻肌动蛋白原聚体的子结构域1移开。Cofilin在骨骼肌f -肌动蛋白Gln41处将色氨酸残基的FRET还原为4-叠氮-2-硝基苯基腐胺（ANP），但在g -肌动蛋白中没有。然而，在F-actin中的Gln41与Cys374被ANP交联后，cofilin结合并没有改变FRET从色氨酸残基到ANP。这表明cofilin的结合和对F-actin的构象作用并不是紧密耦合的。总的来说，本研究为cofilin削弱F-actin的纵向，子结构域2/1接触提供了解决证据。(C) 2002 Elsevier Science Ltd.版权所有。
Structural effects of yeast cofilin on skeletal muscle and yeast actin were examined in solution. Cofilin binding to native actin was non-cooperative and saturated at a 1:1 molar ratio, with K-d less than or equal to 0.05 muM for both CaATP-G-actin and F-actin. Cofilin binding enhanced the fluorescence of dansyl ethylenediamine (DED) attached to Gln41 on the DNase I binding loop of skeletal muscle F-actin and decreased the fluorescence of AEDANS at Cys41 on yeast Q41C/C374S mutant F-actin. However, cofilin had no effect on the spectral properties of DED or AEDANS on CaATP-G-actin. Fluorescence energy transfer (FRET) from tryptophan residues to DED at Gln41 on skeletal muscle actin and to AEDANS at Cys41 on yeast Q41C/ C374S actin was decreased by cofilin binding to F- but not to G-actin. Cofilin inhibited strongly the rate of interprotomer disulfide cross-linking of Cys41. to Cys374 on yeast Q41C mutant F-actin. Binding of cofilin enhanced excimer formation between pyrene probes attached to Cys41 and Cys374 on Q41C F-actin. These results indicate that cofilin alters the interface between subdomains I and 2 and shifts the DNase I binding loop away from subdomain 1 of an adjacent actin protomer. Cofilin reduced FRET from tryptophan residues to 4-azido-2-nitrophenylputrescine (ANP) at Gln41 in skeletal muscle F-but not in G-actin. However, following the interprotomer cross-linking of Gln41 to Cys374 in F-actin by ANP, cofilin binding did not change FRET from the tryptophan residues to ANP. This suggests that cofilin binding and the conformational effect on F-actin are not coupled tightly. Overall, this study provides solution evidence for the weakening of longitudinal, subdomain 2/1 contacts in F-actin by cofilin. (C) 2002 Elsevier Science Ltd. All rights reserved.