Goshima M, Kariya K, Yamawaki-Kataoka Y, Okada T, Shibatohge M, Shima F, Fujimoto E, Kataoka T
Department of Physiology II, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan.
Biochem Biophys Res Commun. 1999 Apr 2;257(1):111-6. doi: 10.1006/bbrc.1999.0420.
Ras proteins are conserved from yeasts to mammals and implicated in regulation of the actin cytoskeleton. The flightless-1 (fli-1) gene of Drosophila melanogaster and its homologs in Caenorhabditis elegans and humans encode proteins (FLI-1) comprising a fusion of a leucine-rich repeats (LRRs) domain and a gelsolin-like domain. This LRRs domain is highly homologous to those of three proteins involved in Ras-mediated signaling; Saccharomyces cerevisiae adenylyl cyclase, C. elegans SUR-8, and mammalian RSP-1. Here we report that the LRRs domain of C. elegans FLI-1 (Ce-FLI-1) associates directly with Ras (Kd = 11 nM) and, when overexpressed, suppresses the heat shock sensitive phenotype of yeast cells bearing the activated RAS2 gene (RAS2(Val-19)). Further, the gelsolin-like domain of Ce-FLI-1 is shown to possess a Ca2+-independent G-actin-binding activity as well as F-actin-binding and -severing activities. FLI-1 may be involved in regulation of the actin cytoskeleton through Ras.
Ras蛋白从酵母到哺乳动物都保守存在，并参与肌动蛋白细胞骨架的调控。果蝇的无翅-1（fli-1）基因及其在秀丽隐杆线虫和人类中的同源物编码的蛋白质（FLI-1）包含一个富含亮氨酸重复序列（LRRs）结构域和一个凝溶胶蛋白样结构域的融合体。这个LRRs结构域与参与Ras介导信号传导的三种蛋白质的结构域高度同源；酿酒酵母腺苷酸环化酶、秀丽隐杆线虫SUR-8和哺乳动物RSP-1。在此我们报道，秀丽隐杆线虫FLI-1（Ce-FLI-1）的LRRs结构域直接与Ras结合（解离常数Kd = 11 nM），并且当过量表达时，可抑制携带激活型RAS2基因（RAS2(Val-19)）的酵母细胞的热休克敏感表型。此外，Ce-FLI-1的凝溶胶蛋白样结构域显示具有不依赖Ca2+的G-肌动蛋白结合活性以及F-肌动蛋白结合和切断活性。FLI-1可能通过Ras参与肌动蛋白细胞骨架的调控。
