Spb1p-directed formation of Gm2922 in the ribosome catalytic center occurs at a late processing stage.
rRNA molecules undergo extensive posttranscriptional modification, predominantly 2'-O-ribose methylation and pseudouridine formation, both of which are guided by the numerous small nucleolar RNAs in eukaryotes. Here, we describe an exception to this rule. The essential yeast nucleolar protein Spb1p is a site-specific rRNA methyltransferase modifying the universally conserved G2922 that is located within the A loop of the catalytic center of the ribosome. The equivalent position in bacteria is the docking site for aminoacyl-tRNA, and it is critical for translation. In sharp contrast to other 2'-O-methylriboses that are formed on the primary transcript, Gm2922 appears at a late processing stage, during the maturation of the 27S pre-rRNA. Thus, eukaryotes have maintained a site-specific enzyme to catalyze the methylation of a nucleotide that plays a crucial role in ribosome biogenesis and translation.
Lapeyre
Bruno
B
Centre de Recherche de Biochimie Macromoléculaire, 1919 Route de Mende, 34293 Montpellier, France. bruno.lapeyre@crbm.cnrs.fr
Purushothaman
Suresh K
SK
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D002457:Cell Extracts; D002458:Cell Fractionation; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006147:Guanine / Q000737:chemistry*; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012335:RNA, Ribosomal / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D002457:Cell Extracts; D005656:Fungal Proteins; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; D029701:Saccharomyces cerevisiae Proteins; D006147:Guanine; D008780:Methyltransferases; C403804:SPB1 protein, S cerevisiae