Translation ability of mitochondrial tRNAsSer with unusual secondary structures in an in vitro translation system of bovine mitochondria.
BACKGROUND
Metazoan mitochondrial (mt) tRNAs are structurally quite different from the canonical cloverleaf secondary structure. The mammalian mt tRNASerGCU for AGY codons (Y = C or U) lacks the entire D arm, whereas tRNASerUGA for UCN codons (N = A, G, C or U) has an extended anti-codon stem. It has been a long-standing problem to prove experimentally how these tRNAsSer work in the mt translation system.


RESULTS
To solve the above-mentioned problem, we examined their translational abilities in an in vitro bovine mitochondrial translation system using transcripts of altered tRNASer analogues derived from bovine mitochondria. Both tRNASer analogues had almost the same ability to form ternary complexes with mt EF-Tu and GTP. The D-arm-lacking tRNASer GCU analogue had considerably lower translational activity than the tRNASerUGA analogue and produced mostly short oligopeptides, up to a tetramer. In addition, tRNASerGCU analogue was disfavoured by the ribosome when other tRNAs capable of decoding the cognate codon were available.


CONCLUSIONS
Both mt tRNASerGCU and tRNASerUGA analogues with unusual secondary structure were found to be capable of translation on the ribosome. However, the tRNASerGCU analogue has some molecular disadvantage on the ribosome, which probably derives from the lack of a D arm.
Hanada
T
T
Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Suzuki
T
T
Yokogawa
T
T
Takemoto-Hori
C
C
Sprinzl
M
M
Watanabe
K
K
D000818:Animals; D001483:Base Sequence; D002417:Cattle; D003062:Codon; D006160:Guanosine Triphosphate / Q000378:metabolism; D066298:In Vitro Techniques; D009690:Nucleic Acid Conformation; D010444:Peptide Elongation Factor Tu / Q000378:metabolism; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding; D014176:Protein Biosynthesis; D012313:RNA / Q000737:chemistry / Q000235:genetics*; D000077278:RNA, Mitochondrial; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics; D012360:RNA, Transfer, Phe / Q000235:genetics; D012362:RNA, Transfer, Ser / Q000737:chemistry / Q000235:genetics*; D046249:Transfer RNA Aminoacylation
D003062:Codon; D011108:Polymers; D000077278:RNA, Mitochondrial; D012346:RNA, Transfer, Amino Acyl; D012360:RNA, Transfer, Phe; D012362:RNA, Transfer, Ser; D012313:RNA; D006160:Guanosine Triphosphate; D010444:Peptide Elongation Factor Tu