Feinberg J, Mery J, Heitz F, Benyamin Y, Roustan C
Centre for Research in Macromolecular Biochemistry (CNRS), Laboratory for Research on Cellular Motility, University of Montpellier 1, France.
Int J Pept Protein Res. 1996 Jan-Feb;47(1-2):62-9. doi: 10.1111/j.1399-3011.1996.tb00811.x.
Gelsolin and thymosin beta4 appear to be two important actin-associated proteins involved in the regulation of actin polymerization. It has been widely demonstrated that thymosin is the major cellular actin-sequestering factor shifting the polymerization equilibrium of actin towards a monomeric state. At the same time gelsolin, a Ca2+ and inositol phosphate sensitive protein, regulates actin filament length. The interactions of these two proteins with actin are rather complex and require the participation of several complementary peptide sequences. We have identified a common motif, (I, V)EKFD, in the two proteins in the functional sequences so far examined. Gelsolin- and thymosin beta4-related peptides including the common motif were synthesized and their structural and functional properties studied. These two sequences exert a major inhibitory effect on salt-induced actin polymerization. We used circular dichroism and Fourier-transform infrared spectroscopy to show that the two synthetic peptides present some secondary structure in solution. As far as the peptide derived from the thymosin sequence was concerned, alpha-helical structure was induced by trifluoroethanol as observed with the full-length molecule. These experiments underscore the importance of the conformational state of peptide fragments in their biological activities. ELISA and fluorescence measurements have been used to identify the binding regions of these fragments to a C-terminal region (subdomain 1) of the actin sequence. Our results also emphasize the relationship between the propensity of small sequences to form secondary structures and their propensity for biological activity as related to actin interaction and inhibition of actin polymerization.
凝溶胶蛋白和β4胸腺素似乎是参与肌动蛋白聚合调节的两种重要的肌动蛋白相关蛋白。已广泛证明，胸腺素是主要的细胞肌动蛋白隔离因子，可使肌动蛋白的聚合平衡向单体状态转变。同时，凝溶胶蛋白是一种对Ca2+和肌醇磷酸敏感的蛋白，可调节肌动蛋白丝的长度。这两种蛋白与肌动蛋白的相互作用相当复杂，需要几个互补肽序列的参与。在迄今为止研究的功能序列中，我们在这两种蛋白中鉴定出一个共同基序，即（I，V）EKFD。合成了包含该共同基序的凝溶胶蛋白和β4胸腺素相关肽，并研究了它们的结构和功能特性。这两个序列对盐诱导的肌动蛋白聚合具有主要抑制作用。我们使用圆二色性和傅里叶变换红外光谱表明，这两种合成肽在溶液中呈现出一些二级结构。就源自胸腺素序列的肽而言，正如全长分子所观察到的那样，三氟乙醇诱导了α螺旋结构。这些实验强调了肽片段的构象状态在其生物活性中的重要性。已使用酶联免疫吸附测定（ELISA）和荧光测量来鉴定这些片段与肌动蛋白序列C末端区域（亚结构域1）的结合区域。我们的结果还强调了小序列形成二级结构的倾向与其与肌动蛋白相互作用和抑制肌动蛋白聚合相关的生物活性倾向之间的关系。
