The Cm56 tRNA modification in archaea is catalyzed either by a specific 2'-O-methylase, or a C/D sRNP.
We identified the first archaeal tRNA ribose 2'-O-methylase, aTrm56, belonging to the Cluster of Orthologous Groups (COG) 1303 that contains archaeal genes only. The corresponding protein exhibits a SPOUT S-adenosylmethionine (AdoMet)-dependent methyltransferase domain found in bacterial and yeast G18 tRNA 2'-O-methylases (SpoU, Trm3). We cloned the Pyrococcus abyssi PAB1040 gene belonging to this COG, expressed and purified the corresponding protein, and showed that in vitro, it specifically catalyzes the AdoMet-dependent 2'-O-ribose methylation of C at position 56 in tRNA transcripts. This tRNA methylation is present only in archaea, and the gene for this enzyme is present in all the archaeal genomes sequenced up to now, except in the crenarchaeon Pyrobaculum aerophilum. In this archaea, the C56 2'-O-methylation is provided by a C/D sRNP. Our work is the first demonstration that, within the same kingdom, two different mechanisms are used to modify the same nucleoside in tRNAs.
IEFG 109, Laboratoire de Biologie Moléculaire des Eucaryotes, (LBME) UMR CNRS/UHP 5099 118, route de Narbonne, 31062 Toulouse Cedex 02, France.
Marie-Hélène
MH
Renalier
Nicole
N
Joseph
Christine
C
Gaspin
Patricia
P
Thebault
Annie
A
Mougin
D000595:Amino Acid Sequence; D002384:Catalysis; D003001:Cloning, Molecular; D016384:Consensus Sequence; D003596:Cytosine / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D020745:Genome, Archaeal; D005982:Glutathione Transferase / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames; D010802:Phylogeny; D017433:Protein Structure, Secondary; D041543:Pyrobaculum / Q000235:genetics / Q000378:metabolism; D043903:Pyrococcus abyssi / Q000201:enzymology / Q000235:genetics; D019642:RNA, Archaeal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020537:RNA, Small Nucleolar / Q000235:genetics / Q000378:metabolism*; D012343:RNA, Transfer / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature; D012359:tRNA Methyltransferases / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*
D019642:RNA, Archaeal; D020537:RNA, Small Nucleolar; D011994:Recombinant Proteins; D003596:Cytosine; D012343:RNA, Transfer; D012359:tRNA Methyltransferases; D005982:Glutathione Transferase