title: Mutational analysis of the conserved bases C1402 and A1500 in the center of the decoding domain of Escherichia coli 16 S rRNA reveals an important tertiary interaction.
abstract: Interactions within the decoding center of the 30 S ribosomal subunit have been investigated by constructing all 15 possible mutations at nucleotides C1402 and A1500 in helix 44 of 16 S rRNA. As expected, most of the mutations resulted in highly deleterious phenotypes, consistent with the high degree of conservation of this region and its functional importance. A total of seven mutants were viable under conditions where the mutant ribosomes comprised 100 % of the ribosomal pool. A suppressor mutation specific for the C1402U-A1500G mutant was isolated at position 1520 in helix 45 of 16 S rRNA. In addition, lack of dimethylation of A1518/A1519 caused by mutation of the ksgA methylase enhanced the deleterious effect of many of the 1402/1500 mutations. These data suggest that a higher-order interaction between helices 44 and 45 in 16 S rRNA is important for the proper functioning of the ribosome. This is consistent with the recent high-resolution crystal structures of the 30 S subunit, which show a tertiary interaction between the 1402/1500 region of helix 44 and the dimethyl A stem loop.
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry J. W. Wilson Laboratory, Brown University, 69 Brown Street Providence, RI 02912, USA.
authors.forename: A
authors.initials: A
authors.lastname: Vila-Sanjurjo
authors.forename: A E
authors.initials: AE
authors.lastname: Dahlberg
mesh_terms: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D017124:Conserved Sequence / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000235:genetics; D021122:Protein Subunits; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013489:Suppression, Genetic / Q000235:genetics
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D021122:Protein Subunits; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D008780:Methyltransferases; C047346:16S rRNA (adenine(1518)-N(6)-adenine(1519)-N(6))-dimethyltransferase; C100305:kasugamycin