Munshi R, Kandl K A, Carr-Schmid A, Whitacre J L, Adams A E, Kinzy T G
Department of Molecular Genetics and Microbiology, UMDNJ Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
Genetics. 2001 Apr;157(4):1425-36. doi: 10.1093/genetics/157.4.1425.
The translation elongation factor 1 complex (eEF1) plays a central role in protein synthesis, delivering aminoacyl-tRNAs to the elongating ribosome. The eEF1A subunit, a classic G-protein, also performs roles aside from protein synthesis. The overexpression of either eEF1A or eEF1B alpha, the catalytic subunit of the guanine nucleotide exchange factor, in Saccharomyces cerevisiae results in effects on cell growth. Here we demonstrate that overexpression of either factor does not affect the levels of the other subunit or the rate or accuracy of protein synthesis. Instead, the major effects in vivo appear to be at the level of cell morphology and budding. eEF1A overexpression results in dosage-dependent reduced budding and altered actin distribution and cellular morphology. In addition, the effects of excess eEF1A in actin mutant strains show synthetic growth defects, establishing a genetic connection between the two proteins. As the ability of eEF1A to bind and bundle actin is conserved in yeast, these results link the established ability of eEF1A to bind and bundle actin in vitro with nontranslational roles for the protein in vivo.
翻译延伸因子1复合物（eEF1）在蛋白质合成中起核心作用，将氨酰tRNA转运至正在延伸的核糖体。eEF1A亚基是一种典型的G蛋白，除蛋白质合成外还发挥其他作用。在酿酒酵母中，eEF1A或鸟嘌呤核苷酸交换因子的催化亚基eEF1Bα的过表达会对细胞生长产生影响。在此我们证明，任一因子的过表达均不影响另一亚基的水平，也不影响蛋白质合成的速率或准确性。相反，体内的主要影响似乎发生在细胞形态和出芽水平。eEF1A的过表达导致出芽呈剂量依赖性减少，肌动蛋白分布和细胞形态改变。此外，肌动蛋白突变株中过量eEF1A的影响表现为合成生长缺陷，从而在这两种蛋白之间建立了遗传联系。由于eEF1A结合和捆绑肌动蛋白的能力在酵母中是保守的，这些结果将eEF1A在体外已确定的结合和捆绑肌动蛋白的能力与该蛋白在体内的非翻译作用联系起来。
