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

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

Nucleic acids research (2003-04-12)
Louis Droogmans, Martine Roovers, Janusz M Bujnicki, Catherine Tricot, Thomas Hartsch, Victor Stalon, Henri Grosjean
ABSTRACT

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.

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Roche
Isopropyl-β-D-thiogalactoside, mol wt 238.3, pkg of 1 g (10724815001), pkg of 5 g (11411446001)