title: The fission yeast Schizosaccharomyces pombe has two distinct tRNase Z(L)s encoded by two different genes and differentially targeted to the nucleus and mitochondria.
abstract: tRNase Z is the endonuclease that is involved in tRNA 3'-end maturation by removal of the 3'-trailer sequences from tRNA precursors. Most eukaryotes examined to date, including the budding yeast Saccharomyces cerevisiae and humans, have a single long form of tRNase Z (tRNase ZL). In contrast, the fission yeast Schizosaccharomyces pombe contains two candidate tRNase ZLs encoded by the essential genes sptrz1+ and sptrz2+. In the present study, we have expressed recombinant SpTrz1p and SpTrz2p in S. pombe. Both recombinant proteins possess precursor tRNA 3'-endonucleolytic activity in vitro. SpTrz1p localizes to the nucleus and has a simian virus 40 NLS (nuclear localization signal)-like NLS at its N-terminus, which contains four consecutive arginine and lysine residues between residues 208 and 211 that are critical for the NLS function. In contrast, SpTrz2p is a mitochondrial protein with an N-terminal MTS (mitochondrial-targeting signal). High-level overexpression of sptrz1+ has no detectable phenotypes. In contrast, strong overexpression of sptrz2+ is lethal in wild-type cells and results in morphological abnormalities, including swollen and round cells, demonstrating that the correct expression level of sptrz2+ is critical. The present study provides evidence for partitioning of tRNase Z function between two different proteins in S. pombe, although we cannot rule out specialized functions for each protein.
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210046, China.
authors.forename: Xuhua
authors.initials: X
authors.lastname: Gan
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Haiyan
authors.initials: H
authors.lastname: Yu
authors.forename: Hongmei
authors.initials: H
authors.lastname: Dai
authors.forename: Jinyu
authors.initials: J
authors.lastname: Liu
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
mesh_terms: D002467:Cell Nucleus / Q000201:enzymology / Q000378:metabolism; D004722:Endoribonucleases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D005800:Genes, Fungal; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D050296:Microbial Viability; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism; D050505:Mutant Proteins / Q000096:biosynthesis / Q000378:metabolism; D019913:Nuclear Localization Signals / Q000378:metabolism; D021382:Protein Sorting Signals; D021381:Protein Transport; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012343:RNA, Transfer / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D050505:Mutant Proteins; D019913:Nuclear Localization Signals; D021382:Protein Sorting Signals; D012322:RNA Precursors; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D012343:RNA, Transfer; D004722:Endoribonucleases; C512661:tRNase Z, S cerevisiae