title: Variable region V1 of Saccharomyces cerevisiae 18S rRNA participates in biogenesis and function of the small ribosomal subunit.
abstract: The role of helix 6, which forms the major portion of the most 5'-located expansion segment of Saccharomyces cerevisiae 18S rRNA, was studied by in vivo mutational analysis. Mutations that increased the size of the helical part and/or the loop, even to a relatively small extent, abolished 18S rRNA formation almost completely. Concomitantly, 35S pre-rRNA and an abnormal 23S precursor species accumulated. rDNA units containing these mutations did not support cell growth. A deletion removing helix 6 almost completely, on the other hand, had a much less severe effect on the formation of 18S rRNA, and cells expressing only the mutant rRNA remained able to grow, albeit at a much reduced rate. Disruption of the apical A.U base pair by a single point mutation did not cause a noticeable reduction in the level of 18S rRNA but did result in a twofold lower growth rate of the cells. This effect could not be reversed by introduction of a second point mutation that restores base pairing. We conclude that both the primary and the secondary structure of helix 6 play an important role in the formation and the biological function of the 40S subunit.
authors.affiliation: Department of Biochemistry and Molecular Biology, IMBW, BioCentrum Amsterdam, Vrije Universiteit, de Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands.
authors.forename: R W
authors.initials: RW
authors.lastname: van Nues
authors.forename: J
authors.initials: J
authors.lastname: Venema
authors.forename: R J
authors.initials: RJ
authors.lastname: Planta
authors.forename: H A
authors.initials: HA
authors.lastname: Raué
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D012337:RNA, Ribosomal, 18S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*
chemical_list: D012335:RNA, Ribosomal; D012337:RNA, Ribosomal, 18S; D012319:RNA Polymerase II