A novel wobble rule found in starfish mitochondria. Presence of 7- methylguanosine at the anticodon wobble position expands decoding capability of tRNA

Satoshi Matsuyama, Takuya Ueda, Pamela F. Crain, James A. McCloskey, Kimitsuna Watanabe

Research output: Contribution to journalArticle

44 Citations (Scopus)


In the starfish mitochondrial (mt) genome, codons AGA and AGG (in addition to AGU and AGC) have been considered to be translated as serine. There is, however, only a single candidate mt tRNA gene responsible for translating these codons and it has a GCT anticodon sequence, but guanosine at the first position of the anticodon should base pair only with pyrimidines according to the conventional wobble rule. To solve this enigma, the mt tRNA (GCU/ser) was purified, and sequence determination in combination with electrospray liquid chromatography/mass spectrometry revealed that 7- methylguanosine is located at the first position of the anticodon. This is the first case in which a tRNA has been found to have 7-methylguanosine at the wobble position. It is suggested that methylation at N-7 of wobbling guanosine endows the tRNA with the capability of forming base pairs with all four nucleotides, A, U, G, and C, and expands the repertoire of codon- anticodon interaction. This finding indicates that a nonuniversal genetic code in starfish has been generated by base modification in the tRNA anticodon.

Original languageEnglish
Pages (from-to)3363-3368
Number of pages6
JournalJournal of Biological Chemistry
Issue number6
Publication statusPublished - 1998 Feb 6


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this