title: rRNA suppressor of a eukaryotic translation initiation factor 5B/initiation factor 2 mutant reveals a binding site for translational GTPases on the small ribosomal subunit.
abstract: The translational GTPases promote initiation, elongation, and termination of protein synthesis by interacting with the ribosome. Mutations that impair GTP hydrolysis by eukaryotic translation initiation factor 5B/initiation factor 2 (eIF5B/IF2) impair yeast cell growth due to failure to dissociate from the ribosome following subunit joining. A mutation in helix h5 of the 18S rRNA in the 40S ribosomal subunit and intragenic mutations in domain II of eIF5B suppress the toxic effects associated with expression of the eIF5B-H480I GTPase-deficient mutant in yeast by lowering the ribosome binding affinity of eIF5B. Hydroxyl radical mapping experiments reveal that the domain II suppressors interface with the body of the 40S subunit in the vicinity of helix h5. As the helix h5 mutation also impairs elongation factor function, the rRNA and eIF5B suppressor mutations provide in vivo evidence supporting a functionally important docking of domain II of the translational GTPases on the body of the small ribosomal subunit.
authors.affiliation: Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2427, USA.
authors.forename: Byung-Sik
authors.initials: BS
authors.lastname: Shin
authors.forename: Joo-Ran
authors.initials: JR
authors.lastname: Kim
authors.forename: Michael G
authors.initials: MG
authors.lastname: Acker
authors.forename: Kathryn N
authors.initials: KN
authors.lastname: Maher
authors.forename: Jon R
authors.initials: JR
authors.lastname: Lorsch
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Dever
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry / Q000235:genetics*; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism*; D016153:Genes, Suppressor; D006639:Histidine; D017665:Hydroxyl Radical; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000378:metabolism; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012337:RNA, Ribosomal, 18S / Q000737:chemistry / Q000235:genetics*; D054679:Ribosome Subunits, Small / Q000201:enzymology* / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics*; D013489:Suppression, Genetic / Q000235:genetics*
chemical_list: D015852:Eukaryotic Initiation Factor-2; C451460:FUN12 protein, S cerevisiae; D020648:Peptide Elongation Factor 1; D012337:RNA, Ribosomal, 18S; D029701:Saccharomyces cerevisiae Proteins; D017665:Hydroxyl Radical; D006639:Histidine; D020558:GTP Phosphohydrolases