J. Moriya et al., A NOVEL MODIFIED NUCLEOSIDE FOUND AT THE FIRST POSITION OF THE ANTICODON OF METHIONINE TRANSFER-RNA FROM BOVINE LIVER-MITOCHONDRIA, Biochemistry, 33(8), 1994, pp. 2234-2239
Methionine tRNA was purified from bovine liver mitochondria, and its n
ucleotide sequence was determined. The tRNA possesses only three postt
ranscriptionally modified nucleosides, two pseudouridines in the antic
odon and T stems and a previously unknown nucleoside specified by the
gene sequence as cytidine, in the first position of the anticodon. Str
ucture analysis of the anticodon nucleoside by mass spectrometry revea
led a molecular mass 28 Da greater than that of cytidine, and unmodifi
ed ribose, with substitution at C-5 implied by hydrogen-deuterium exch
ange experiments. Proton NMR of the intact tRNA showed presence of a f
ormyl moiety, thus leading to the candidate structure 5-formylcytidine
(f(5)C), not a previously known compound. The structure assignment wa
s confirmed by chemical synthesis and comparison of data from combined
HPLC/mass spectrometry and proton NMR for the natural and synthetic n
ucleosides. The potential function of f(5)C in the tRNA(Met) anticodon
is discussed with regard to codon-anticodon interactions.