Valentin-Ranc C, Carlier M F
Laboratoire d'Enzymologie, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
J Biol Chem. 1992 Oct 25;267(30):21543-50.
The nature of the kinetic intermediates involved in S1-induced polymerization of G-actin into F-acto-S1-decorated filaments has been investigated using as probes light scattering, the fluorescence of pyrenyl- or NBD-labeled actin, and the anisotropy of fluorescence of N-iodoacetyl-N'-(5-sulfo-1-napthyl)ethylene diamine (AEDANS)-labeled actin. With AEDANS-G-actin, the initial formation of a ternary G2S complex between two G-actin and one S1 molecules (Valentin-Ranc, C., Combeau, C., Carlier, M. F., and Pantaloni, D. (1991) J. Biol. Chem. 266, 17871-17879) has been confirmed. Data obtained with all probes are consistent with the subsequent rapid formation of G-actin-S1 oligomers in which the actin/S1 molar ratio is 2:1. Oligomers form above 0.6 microM G-actin with S1(A1) and above 3.5 microM G-actin with S1(A2), at 20 degrees C. Oligomerization is endothermic with a delta H of 14 kcal/mol. A tentative model is proposed to comprehensively account for the data and the structural features of the F-actin-S1 filament. Within this model, longitudinal actin-actin interactions take place in G2S, and lateral, hydrophobic actin-actin interactions appear upon formation of (G2S)n oligomers.
利用光散射、芘基或NBD标记肌动蛋白的荧光以及N-碘乙酰-N'-(5-磺基-1-萘基)乙二胺（AEDANS）标记肌动蛋白的荧光各向异性作为探针，研究了S1诱导G-肌动蛋白聚合成F-肌动蛋白-S1修饰细丝过程中涉及的动力学中间体的性质。对于AEDANS-G-肌动蛋白，已证实两个G-肌动蛋白和一个S1分子之间最初形成三元G2S复合物（瓦伦丁-兰克，C.，孔博，C.，卡利耶，M.F.，和潘塔洛尼，D.（1991年）《生物化学杂志》266，17871 - 17879）。用所有探针获得的数据与随后快速形成肌动蛋白/S1摩尔比为2:1的G-肌动蛋白-S1寡聚体一致。在20℃时，用S1(A1)时，寡聚体在0.6微摩尔/升以上的G-肌动蛋白浓度时形成，用S1(A2)时，在3.5微摩尔/升以上的G-肌动蛋白浓度时形成。寡聚化是吸热的，焓变ΔH为14千卡/摩尔。提出了一个初步模型，以全面解释这些数据以及F-肌动蛋白-S1细丝的结构特征。在这个模型中，纵向肌动蛋白-肌动蛋白相互作用发生在G2S中，而横向、疏水的肌动蛋白-肌动蛋白相互作用在(G2S)n寡聚体形成时出现。
