title: The folding capacity of the mature domain of the dual-targeted plant tRNA nucleotidyltransferase influences organelle selection.
abstract: tRNA-NTs (tRNA nucleotidyltransferases) are required for the maturation or repair of tRNAs by ensuring that they have an intact cytidine-cytidine-adenosine sequence at their 3'-termini. Therefore this enzymatic activity is found in all cellular compartments, namely the nucleus, cytoplasm, plastids and mitochondria, in which tRNA synthesis or translation occurs. A single gene codes for tRNA-NT in plants, suggesting a complex targeting mechanism. Consistent with this, distinct signals have been proposed for plastidic, mitochondrial and nuclear targeting. Our previous research has shown that in addition to N-terminal targeting information, the mature domain of the protein itself modifies targeting to mitochondria and plastids. This suggests the existence of an as yet unknown determinate for the distribution of dual-targeted proteins between these two organelles. In the present study, we explore the enzymatic and physicochemical properties of tRNA-NT variants to correlate the properties of the enzyme with the intracellular distribution of the protein. We show that alteration of tRNA-NT stability influences its intracellular distribution due to variations in organelle import capacities. Hence the fate of the protein is determined not only by the transit peptide sequence, but also by the physicochemical properties of the mature protein.
authors.affiliation: Department of Chemistry and Biochemistry and Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke St. W., Montréal, Québec, Canada H4B 1R6.
authors.forename: Matthew
authors.initials: M
authors.lastname: Leibovitch
authors.forename: Daniela
authors.initials: D
authors.lastname: Bublak
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Hanic-Joyce
authors.forename: Bodo
authors.initials: B
authors.lastname: Tillmann
authors.forename: Nadine
authors.initials: N
authors.lastname: Flinner
authors.forename: Daniel
authors.initials: D
authors.lastname: Amsel
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Scharf
authors.forename: Oliver
authors.initials: O
authors.lastname: Mirus
authors.forename: Paul B M
authors.initials: PB
authors.lastname: Joyce
authors.forename: Enrico
authors.initials: E
authors.lastname: Schleiff
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism; D002942:Circular Dichroism; D019295:Computational Biology; D015388:Organelles / Q000201:enzymology* / Q000378:metabolism*; D012316:RNA Nucleotidyltransferases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D012316:RNA Nucleotidyltransferases; C023198:tRNA nucleotidyltransferase