tailieunhanh - Báo cáo khoa học: Endoribonucleases – enzymes gaining spotlight in mRNA metabolism

The efficient turnover of messenger RNA represents an important mecha-nism that allows the cell to control gene expression. Until recently, the mechanism of mRNA decay was mainly attributed to exonucleases, com-prising enzymes that degrade RNAs from the ends of the molecules. | ỊFEBS Journal REVIEW ARTICLE Endoribonucleases - enzymes gaining spotlight in mRNA metabolism Wai Ming Li Tavish Barnes and Chow H. Lee Chemistry Program University of Northern British Columbia Prince George Canada Keywords decay degradation endoribonucleases eukaryotes mRNA RNA metabolism Correspondence C. H. Lee Chemistry Program University of Northern BC 3333 University Way Prince George BC V2N 4Z9 Canada Fax 1 250 960 5170 Tel 1 250 960 5413 E-mail leec@ Received 14 August 2009 revised 14 October 2009 accepted 9 November 2009 doi The efficient turnover of messenger RNA represents an important mechanism that allows the cell to control gene expression. Until recently the mechanism of mRNA decay was mainly attributed to exonucleases comprising enzymes that degrade RNAs from the ends of the molecules. This article summarizes the endoribonucleases comprising enzymes that cleave RNA molecules internally which were identified in more recent years in eukaryotic mRNA metabolism. Endoribonucleases have received little attention in the past based on the difficulty in their identification and a lack of understanding of their physiological significance. This review aims to compare the similarities and differences among this group of enzymes as well as their known cellular functions. Despite the many differences in protein structure and thus difficulties in identifying them based on amino acid sequence most endoribonucleases possess essential cellular functions and have been shown to play an important role in mRNA turnover. Introduction Until recently it was generally considered that mRNA decay in higher eukaryotes occurs primarily through the ends of the molecule via two exonucleolytic pathways. One involves deadenylation followed by 3 -5 exonucleolytic degradation as catalyzed by a putative complex of exonucleases termed the exosome 1 . The other involves 5 decapping followed by 5 -3 exonucle-olytic decay 1 . This traditional view of