Nucleotide sequence of formylmethionine tRNA from an extreme thermophile, Thermus thermophilus HB 8

Abstract

The nucleotide sequence of formylmethionine tRNA from an extreme thermophile, Thermus thermophilus HB 8 was determined by a combination of classical methods using unlabelled sample to sequence RNase T and RNase A-fragments and a rapid sequencing gel thechnique using 5′- 32 P- 1 labelled sample to deduce the complete sequence. Formylmethionine tRNA from T.thermophilus is composed of two species, tRNA f2Met and tRNA f1Met , their nucleotide sequence being almost identical to each other and also identical to that of E.coli tRNA fMet except a slight replacement and modification. Both species contained modification at three points which does not exist in E.coli tRNA Metf ; 2′- 0 -methylation at G 19 , N -l-methylation at A 59 and 2-thiolation at T 55 . Moreover, U 51 in E.coli tRNA fMet was replaced by C in both species. tRNA f2Met had a reversed G-C pair at position 52 and 64. Other parts were mostly common to all prokaryotic initiator tRNAs so far reported. The thermostability of these thermophile initiator tRNAs was discussed in relation to their unique modifications.