TRANSLATION ELONGATION FACTOR-III (EP-3) - AN EVOLVING EUKARYOTIC RIBOSOMAL-PROTEIN
TRANSLATION ELONGATION FACTOR-III (EP-3) - AN EVOLVING EUKARYOTIC RIBOSOMAL-PROTEIN
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DOI：
10.1007/bf01215185
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发表时间：
1995-09-01
影响因子：
3.9
通讯作者：
TUITE, MF
中科院分区：
文献类型：
--
作者：
BELFIELD, GP;ROSSSMITH, NJ;TUITE, MF
真菌似乎是独特的，在他们的第三个可溶性翻译延伸因子的要求。该因子，命名为延伸因子3（EF-3），表现出核糖体依赖性ATP酶和GTdR酶活性，其不是真菌核糖体固有的，但是对于体内翻译延伸是必需的。EF-3多肽已经在广泛的真菌物种中被鉴定，并且编码EF-3（YEF 3）的基因已经从四种真菌物种（酿酒酵母、白色念珠菌、季氏念珠菌和卡氏肺孢子虫）中分离。计算机辅助分析的预测S。酿酒酵母EF-3氨基酸序列用于鉴定几个潜在的功能结构域：两个ATP结合/催化结构域与ATP结合盒（ABC）蛋白家族成员中的等同结构域保守，一个氨基末端区域显示出与E. coli S5核糖体蛋白，以及与rRNA、tRNA和mRNA预测相互作用的区域。此外，还发现EF-3显示与肌球蛋白的氨基酸相似性，肌球蛋白的细胞功能是提供肌肉的动力。这些区域的鉴定为EF-3的进化和功能提供了线索。预测的功能区域是保守的所有已知的真菌EF-3蛋白和最近描述的同源物编码的小球藻病毒CVK 2。我们提出EF-3可能通过改变核糖体“精确中心”的构象和活性，在核糖体优化真菌蛋白质合成的精确性中发挥作用，所述核糖体“精确中心”相当于E.大肠杆菌核糖体。此外，我们认为EF-3代表了一种进化的核糖体蛋白，其性质类似于高等真核生物核糖体的内在ATP酶活性，这对真菌与其他真核生物的进化分歧具有更广泛的意义。
Fungi appear to be unique in their requirement for a third soluble translation elongation factor. This factor, designated elongation factor 3 (EF-3), exhibits ribosome-dependent ATPase and GTPase activities that are not intrinsic to the fungal ribosome but are nevertheless essential for translation elongation in vivo. The EF-3 polypeptide has been identified in a wide range of fungal species and the gene encoding EF-3 (YEF3) has been isolated from four fungal species (Saccharomyces cerevisiae, Candida albicans, Candida guillermondii, and Pneumocystis carinii). Computer-assisted analysis of the predicted S. cerevisiae EF-3 amino acid sequence was used to identify several potential functional domains; two ATP binding/catalytic domains conserved with equivalent domains in members of the ATP-Binding Cassette (ABC) family of proteins, an amino-terminal region showing significant similarity to the E. coli S5 ribosomal protein, and regions of predicted interaction with rRNA, tRNA, and mRNA. Furthermore, EF-3 was also found to display amino acid similarity to myosin proteins whose cellular function is to provide the motive force of muscle. The identification of these regions provides clues to both the evolution and function of EF-3. The predicted functional regions are conserved among all known fungal EF-3 proteins and a recently described homologue encoded by the Chlorella virus CVK2. We propose that EF-3 may play a role in the ribosomal optimization of the accuracy of fungal protein synthesis by altering the conformation and activity of a ribosomal ''accuracy center,'' which is equivalent to the S4-S5-S12 ribosomal protein accuracy center domain of the E. coli ribosome. Furthermore, we suggest that EF-3 represents an evolving ribosomal protein with properties analogous to the intrinsic ATPase activities of higher eukaryotic ribosomes, which has wider implications for the evolutionary divergence of fungi from other eukaryotes.