Cloning and characterization of tRNA (m1A58) methyltransferase (TrmI) from Thermus thermophilus HB27, a protein required for cell growth at extreme temperatures

Nucleic Acids Res. 2003 Apr 15;31(8):2148-56. doi: 10.1093/nar/gkg314.


N1-methyladenosine (m1A) is found at position 58 in the T-loop of many tRNAs. In yeast, the formation of this modified nucleoside is catalyzed by the essential tRNA (m1A58) methyltransferase, a tetrameric enzyme that is composed of two types of subunits (Gcd14p and Gcd10p). In this report we describe the cloning, expression and characterization of a Gcd14p homolog from the hyperthermophilic bacterium Thermus thermophilus. The purified recombinant enzyme behaves as a homotetramer of 150 kDa by gel filtration and catalyzes the site- specific formation of m1A at position 58 of the T-loop of tRNA in the absence of any other complementary protein. S-adenosylmethionine is used as donor of the methyl group. Thus, we propose to name the bacterial enzyme TrmI and accordingly its structural gene trmI. These results provide a key evolutionary link between the functionally characterized two-component eukaryotic enzyme and the recently described crystal structure of an uncharacterized, putative homotetrameric methyltransferase Rv2118c from Mycobacterium tuberculosis. Interest ingly, inactivation of the T.thermophilus trmI gene results in a thermosensitive phenotype (growth defect at 80 degrees C), which suggests a role of the N1-methylation of tRNA adenosine-58 in adaptation of life to extreme temperatures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Division / genetics
  • Chromatography, Gel
  • Cloning, Molecular
  • Dimerization
  • Electrophoresis, Polyacrylamide Gel
  • Hot Temperature
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • RNA, Transfer, Asp / metabolism
  • Sequence Homology, Amino Acid
  • Temperature
  • Thermus thermophilus / enzymology
  • Thermus thermophilus / genetics*
  • Thermus thermophilus / growth & development
  • tRNA Methyltransferases / genetics*
  • tRNA Methyltransferases / isolation & purification
  • tRNA Methyltransferases / metabolism


  • RNA, Transfer, Asp
  • tRNA Methyltransferases
  • tRNA (adenine(58)-N(1))-methyltransferase

Associated data

  • GENBANK/AJ516007