Effect of temperature on the mechanism of actin polymerization.
Effect of temperature on the mechanism of actin polymerization.
复制标题
温度对肌动蛋白聚合机制的影响。
DOI：
10.1021/bi00369a014
复制
发表时间：
1986
期刊：
影响因子：
2.9
通讯作者：
Frieden,C
中科院分区：
文献类型：
--
作者：
Zimmerle,CT;Frieden,C
华盛顿大学医学院生物化学系，圣路易斯，密苏里州63110，1986年5月7日接收; 1986年7月2日接收的修订版Mandarin pt摘要：通过使用不同浓度的Mg 2+、Ca 2+和G-肌动蛋白，在pH 8时，测量了Mg 2+诱导的兔骨骼肌G-肌动蛋白聚合速率作为温度的函数。聚合机理类似于在此pH下提出的聚合机理[Frieden，C.等人（1983）Proc. Acad. Sci. USA 80，6513-6517]发现拟合10 - 35 ℃的数据。从动力学数据来看，在任何温度下都没有发现肌动蛋白丝断裂的证据。二聚体的形成是对温度最敏感的步骤，从10 ℃到35 ℃，正向和反向速率常数的比率变化4个数量级。在这个温度变化，所有其他比率的正向和反向速率常数的变化7倍或更少，和临界浓度几乎保持不变。通过使用N-（碘乙酰基）-7N-（5-磺基-1-萘基）乙二胺标记的肌动蛋白或通过模拟聚合反应的全时过程来测量，随着温度的升高，G-肌动蛋白单体的可逆Mg 2+诱导的异构化在更大程度上发生。这部分是由于随着温度的升高，Mg 2+结合变得更紧密，而Ca 2+结合变得更弱。通过使用由等离子体凝溶胶蛋白成核的肌动蛋白确定的从弯曲尖端的延伸率显示出比扩散限制反应所预期的略大的温度依赖性。轴蛋白可以通过经典描述为成核-延伸反应的聚合过程从单体形式（G-肌动蛋白）转化为长螺旋聚合物（F-肌动蛋白）1（Oosawa和加塞，1962）。这种体外聚合过程受到环境变量如pH、温度和离子强度的强烈影响（加塞等人，1962;加塞，1969），并且肌动蛋白在体内的组装或分解可能受到类似因素以及肌动蛋白结合蛋白的影响。因此，详细了解这些环境因素发挥的作用可能是重要的了解在体内肌动蛋白聚合的调节和调制。
Department of Biological Chemistry, Washington University School of Medicine, St. Louis, Missouri 63110 Received May 7, 1986; Revised Manuscript Received July 2, 1986 abstract: The rate of the Mg2+-inducedpolymerization of rabbit skeletal muscle G-actin has been measured as as function of temperature at pH 8 by using various concentrations of Mg2+, Ca2+, and G-actin. A polymerization mechanism similar to that proposed at thispH [Frieden, C.(1983) Proc. Natl. Acad. Sci. USA 80, 6513-6517] was found to fit the data from 10 to 35 C. From the kinetic data, no evidence for actin filament fragmentation was found at any temperature. Dimer formation is the most temperature-sensitive step, with the ratio of forward and reverse rate constants changing 4 orders of magnitude from 10 to 35 C. Over this temperature change, all other ratios of forward and reverse rate constants change 7-fold or less, and the critical concentration remains nearly constant. The reversible Mg2+-induced isom-erization of G-actin monomer occurs to a greater extent with increasing temperature, measured either by using iV-(iodoacetyl)-7V-(5-sulfo-l-naphthyl) ethylenediamine-labeled actin or by simulation of the full-time course of the polymerization reaction. This is partially due to Mg2+ binding becoming tighter, and Ca2+ binding becoming weaker, with increasing temperature. Elongation rates from the filament-pointed end, determined by using actin nucleated by plasma gelsolin, show a temperature dependence slightly larger than that expected for a diffusion-limited reaction.. Axtin can undergo transformation from a monomeric form (G-actin) to a long helical polymer (F-actin) 1 by a polymerization process classically described as a nucleation-elongation reaction (Oosawa & Kasai, 1962). This polymerization pro-cess in vitro is strongly influenced by environmental variables such as pH, temperature, and ionic strength (Kasai et al., 1962; Kasai, 1969), and actin assembly or disassembly in vivo is probably influenced by similar factors as well as by actin binding proteins. Thus, detailed knowledge of the role such environmental factors play may be important for understanding the regulation and modulation of in vivo actin po-lymerization.