CHARACTERIZATION OF 3 NEW SNRNAS FROM SACCHAROMYCES-CEREVISIAE - SNR34, SNR35 AND SNR36

Genes for three novel snRNAs of Saccharomyces cerevisiae have been iso lated, sequenced and tested for essentiality. The RNAs encoded by thes e 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, ba sed on extraction properties and association with fibrillarin. SnR34 a nd snR35 contain a trimethylguanosine cap, but this feature is absent from snR36. The novel RNAs lack elements conserved among several other snoRNAs, including box C, box D and long sequence complementarities w ith rRNA. Genetic disruption analyses showed each of the RNAs to be di spensable and a haploid strain lacking all three RNAs and a previously characterized fourth snoRNA (snR33) is also viable. No differences in the levels of precursors or mature rRNAs were apparent in the four ge ne knockout strain. Possible roles for the new RNAs in ribosome biogen esis are discussed.