Feinberg J, Kwiatek O, Astier C, Diennet S, Mery J, Heitz F, Benyamin Y, Roustan C
Centre de Recherches de Biochimie Macromoléculaire du CNRS, UMR5539, Laboratoire de Recherche sur la Motilité Cellulaire (EPHE), Montpellier, France.
J Pept Sci. 1998 Apr;4(2):116-27. doi: 10.1002/(SICI)1099-1387(199804)4:2%3C116::AID-PSC135%3E3.0.CO;2-R.
Gelsolin is a protein that severs and caps actin filaments. The two activities are located in the N-terminal half of the gelsolin molecules. Severing and subsequent capping requires the binding of domains 2 and 3 (S2-3) to the side of the filaments to position the N-terminal domain 1 (S1) at the barbed end of actin (actin subdomains 1 and 3). The results provide a structural basis for the gelsolin capping mechanism. The effects of a synthetic peptide derived from the sequence of a binding site located in gelsolin S2 on actin properties have been studied. CD and IR spectra indicate that this peptide presented a secondary structure in solution which would be similar to that expected for the native full length gelsolin molecule. The binding of the synthetic peptide induces conformational changes in actin subdomain 1 and actin oligomerization. An increase in the polymerization rate was observed, which could be attributed to a nucleation kinetics effect. The combined effects of two gelsolin fragments, the synthetic peptide derived from an S2 sequence and the purified segment 1 (S1), were also investigated as a molecule model. The two fragments induced nucleation enhancement and inhibited actin depolymerization, two characteristic properties of capping. In conclusion, for the first time it is reported that the binding of a small synthetic fragment is sufficient to promote efficient capping by S1 at the barbed end of actin filaments.
凝溶胶蛋白是一种能切断并封闭肌动蛋白丝的蛋白质。这两种活性位于凝溶胶蛋白分子的N端一半区域。切断及随后的封闭需要结构域2和3（S2 - 3）与肌动蛋白丝的侧面结合，从而将N端结构域1（S1）定位在肌动蛋白的尖端（肌动蛋白亚结构域1和3）。这些结果为凝溶胶蛋白的封闭机制提供了结构基础。人们已经研究了一种源自凝溶胶蛋白S2中一个结合位点序列的合成肽对肌动蛋白性质的影响。圆二色光谱（CD）和红外光谱（IR）表明，这种肽在溶液中呈现出一种二级结构，类似于天然全长凝溶胶蛋白分子预期的结构。合成肽的结合会诱导肌动蛋白亚结构域1发生构象变化并导致肌动蛋白寡聚化。观察到聚合速率增加，这可归因于成核动力学效应。作为一个分子模型，还研究了凝溶胶蛋白的两个片段（源自S2序列的合成肽和纯化的片段1（S1））的联合作用。这两个片段诱导了成核增强并抑制了肌动蛋白解聚，这是封闭的两个特征性质。总之，首次报道了一个小的合成片段的结合足以促进S1在肌动蛋白丝尖端进行有效的封闭。
