Characterization of three new snRNAs from Saccharomyces cerevisiae: snR34, snR35 and snR36

摘要

Genes for three novel snRNAs of Saccharomyces cerevisiae have been isolated, sequenced and tested for essentiality. The RNAs encoded by these genes are designated snR34, snR35 and snR36 respectively and contain 203, 204 and 182 nucleotides. Each RNA is derived from a single copy gene and all three RNAs are believed to be nucleolar, i.e. snoRNAs, based on extraction properties and association with fibrillarin. SnR34 and snR35 contain a trimethylguanoslne cap, but this feature is absent from snR36. Thenovel RNAs lack elements conserved among several other snoR-NAs, including box C, box D and long sequence complementarities with rRNA. Genetic disruption analyses showed each of the RNAs to be dispensable and a haploid strain lacking all three RNAs anda previously characterized fourth snoRNA (snR33) is also viable. No differences in the levels of precursors or mature rRNAs were apparent in the four gene knock-out strain. Possible roles for the new RNAs in ribosome biogenesis are discussed.