Distinct tRNA modifications in the thermo-acidophilic archaeon, Thermoplasma acidophilum.

Thermoplasma acidophilum is a thermo-acidophilic archaeon. We purified tRNA(Leu) (UAG) from T. acidophilum using a solid-phase DNA probe method and determined the RNA sequence after determining via nucleoside analysis and m(7)G-specific aniline cleavage because it has been reported that T. acidophilum tRNA contains m(7)G, which is generally not found in archaeal tRNAs. RNA sequencing and liquid chromatography-mass spectrometry revealed that the m(7)G modification exists at a novel position 49. Furthermore, we found several distinct modifications, which have not previously been found in archaeal tRNA, such as 4-thiouridine9, archaeosine13 and 5-carbamoylmethyuridine34. The related tRNA modification enzymes and their genes are discussed.