title: Dual targeting of the tRNA nucleotidyltransferase in plants: not just the signal.
abstract: Enzymes involved in tRNA maturation are essential for cytosolic, mitochondrial, and plastid protein synthesis and are therefore localized to these different compartments of the cell. Interestingly, only one isoform of tRNA nucleotidyltransferase (responsible for adding the 3'-terminal cytidine-cytidine-adenosine to tRNAs) has been identified in plants. The present study therefore explored how signals contained on this enzyme allow it to be distributed among the different cell compartments. It is demonstrated that the N-terminal portion of the protein acts as an organellar targeting signal and that differential use of multiple in-frame start codons alters the localization of the protein. Moreover, it is shown that the mature domain has a major impact on the distribution of the protein within the cell. These data indicate that regulation of dual localization involves not only specific N-terminal signals, but also additional factors within the protein or the cell.
authors.affiliation: LMU München, VW-Research group, Department of Biology I, Menzinger Str. 67, D-80638 München, Germany.
authors.forename: Serena Schmidt
authors.initials: SS
authors.lastname: von Braun
authors.forename: Antonino
authors.initials: A
authors.lastname: Sabetti
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Hanic-Joyce
authors.forename: Jun
authors.initials: J
authors.lastname: Gu
authors.forename: Enrico
authors.initials: E
authors.lastname: Schleiff
authors.forename: Paul B M
authors.initials: PB
authors.lastname: Joyce
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D003600:Cytosol / Q000201:enzymology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D007527:Isoenzymes / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D010442:Peptide Chain Initiation, Translational / Q000502:physiology; D018087:Plastids / Q000201:enzymology*; D017434:Protein Structure, Tertiary; D012316:RNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D012316:RNA Nucleotidyltransferases; C023198:tRNA nucleotidyltransferase