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Wobble modification differences and subcellular localization of tRNAs in Leishmania tarentolae : implication for tRNA sorting mechanism
Author(s) -
Kaneko Tomonori,
Suzuki Takeo,
Kapushoc Stephen T.,
Rubio Mary Anne,
Ghazvini Jafar,
Watanabe Kimitsuna,
Simpson Larry,
Suzuki Tsutomu
Publication year - 2003
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdg066
Subject(s) - frontier , library science , transfer rna , biology , artificial intelligence , art history , genetics , computer science , history , rna , gene , archaeology
In Leishmania tarentolae , all mitochondrial tRNAs are encoded in the nuclear genome and imported from the cytosol. It is known that tRNA Glu (UUC) and tRNA Gln (UUG) are localized in both cytosol and mitochondria. We investigated structural differences between affinity‐isolated cytosolic (cy) and mitochondrial (mt) tRNAs for glutamate and glutamine by mass spectrometry. A unique modification difference in both tRNAs was identified at the anticodon wobble position: cy tRNAs have 5‐methoxycarbonylmethyl‐2‐ thiouridine (mcm 5 s 2 U), whereas mt tRNAs have 5‐ methoxycarbonylmethyl‐2′‐ O ‐methyluridine (mcm 5 Um). In addition, a trace portion (4%) of cy tRNAs was found to have 5‐methoxycarbonylmethyluridine (mcm 5 U) at its wobble position, which could represent a common modification intermediate for both modified uridines in cy and mt tRNAs. We also isolated a trace amount of mitochondria‐specific tRNA Lys (UUU) from the cytosol and found mcm 5 U at its wobble position, while its mitochondrial counterpart has mcm 5 Um. Mt tRNA Lys and in vitro transcribed tRNA Glu were imported much more efficiently into isolated mitochondria than the native cy tRNA Glu in an in vitro importation experiment, indicating that cytosol‐specific 2‐thiolation could play an inhibitory role in tRNA import into mitochondria.