An Insertion Peptide in Yeast Glycyl-tRNA Synthetase Facilitates both Productive Docking and Catalysis of Cognate tRNAs

作者：Wu Yi Hua; Chang Chia Pei; Chien Chin I; Tseng Yi Kuan; Wang Chien Chia^*

来源：Molecular and Cellular Biology, 2013, 33(17): 3515-3523.

DOI：10.1128/MCB.00122-13

The yeast Saccharomyces cerevisiae possesses two distinct glycyl-tRNA synthetase (GlyRS) genes: GRS1 and GRS2. GRS1 is dually functional, encoding both cytoplasmic and mitochondrial activities, while GRS2 is dysfunctional and not required for growth. The protein products of these two genes, GlyRS1 and GlyRS2, are much alike but are distinguished by an insertion peptide of GlyRS1, which is absent from GlyRS2 and other eukaryotic homologues. We show that deletion or mutation of the insertion peptide modestly impaired the enzyme%26apos;s catalytic efficiency in vitro (with a 2- to 3-fold increase in K-m and a 5- to 8-fold decrease in k(cat)). Consistently, GRS2 can be conveniently converted to a functional gene via codon optimization, and the insertion peptide is dispensable for protein stability and the rescue activity of GRS1 at 30 degrees C in vivo. A phylogenetic analysis further showed that GRS1 and GRS2 are paralogues that arose from a gene duplication event relatively recently, with GRS1 being the predecessor. These results indicate that GlyRS2 is an active enzyme essentially resembling the insertion peptide-deleted form of GlyRS1. Our study suggests that the insertion peptide represents a novel auxiliary domain, which facilitates both productive docking and catalysis of cognate tRNAs.

• 出版日期2013-9
• 单位中央民族大学