Pittman Yvette R, Kandl Kimberly, Lewis Marcus, Valente Louis, Kinzy Terri Goss
Department of Molecular Genetics, Microbiology, and Immunology, University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
J Biol Chem. 2009 Feb 13;284(7):4739-47. doi: 10.1074/jbc.M807945200. Epub 2008 Dec 18.
Eukaryotic translation elongation factor 1A (eEF1A) both shuttles aminoacyl-tRNA (aa-tRNA) to the ribosome and binds and bundles actin. A single domain of eEF1A is proposed to bind actin, aa-tRNA and the guanine nucleotide exchange factor eEF1Balpha. We show that eEF1Balpha has the ability to disrupt eEF1A-induced actin organization. Mutational analysis of eEF1Balpha F163, which binds in this domain, demonstrates effects on growth, eEF1A binding, nucleotide exchange activity, and cell morphology. These phenotypes can be partially restored by an intragenic W130A mutation. Furthermore, the combination of F163A with the lethal K205A mutation restores viability by drastically reducing eEF1Balpha affinity for eEF1A. This also results in a consistent increase in actin bundling and partially corrected morphology. The consequences of the overlapping functions in this eEF1A domain and its unique differences from the bacterial homologs provide a novel function for eEF1Balpha to balance the dual roles in actin bundling and protein synthesis.
真核生物翻译延伸因子1A（eEF1A）既能将氨酰tRNA（aa - tRNA）转运至核糖体，又能结合并捆绑肌动蛋白。研究表明，eEF1A的单个结构域可结合肌动蛋白、aa - tRNA以及鸟嘌呤核苷酸交换因子eEF1Bα。我们发现eEF1Bα能够破坏eEF1A诱导的肌动蛋白组织。对该结构域中结合的eEF1Bα F163进行突变分析，结果显示其对生长、eEF1A结合、核苷酸交换活性及细胞形态均有影响。这些表型可通过基因内W130A突变部分恢复。此外，F163A与致死性K205A突变的组合通过大幅降低eEF1Bα对eEF1A的亲和力来恢复细胞活力。这还导致肌动蛋白捆绑持续增加，细胞形态得到部分纠正。该eEF1A结构域中重叠功能的后果及其与细菌同源物的独特差异为eEF1Bα在平衡肌动蛋白捆绑和蛋白质合成的双重作用方面提供了一种新功能。
