Identification and functional analysis of a novel box C／D snoRNA from Schizosaccharomyces pombe

By constructing and screening the Schizosaccharomyces pombe nuclear cDNA library, a novel small nucleolar RNAs (snoRNA) was identified. The novel snoRNA displays structural features typical of C/D box snoRNA family and possesses a 10-nt-long rRNA antisense element which is predicted to guide the 2‘-O-methylation of the fission yeast 25S rRNA at G940. As expected, the rRNA ribose-methyla- tion site predicted by the novel snoRNA was precisely mapped by a deoxynucleoside triphosphate concentration-dependent primer extension assay. The comparison of functional element of guide snoRNAs among eukaryotes reveals that the novel snoRNA is a partial counterpart of the budding yeast snR60 and was termed snR60-11, snR60-Ⅱ gene nested in the intron of a non-coding RNA gene with an unknown function, which is the first example of a yeast snoRNA encoded in an intron of a non-coding RNA gene. Furthermore, a number of yeast snR60 homologues were also identified from other fungi and fly. Our results reveal that snR60 exhibits diverse genomic organization in eukaryotes, implying the high mobility of snR60 gene in the course of evolution.

Identification and functional analysis of a novel box C/D snoRNA fromSchizosaccharomyces pombe

By constructing and screening the Schizosac-charomyces pombe nuclear cDNA library, a novel small nu-cleolar RNAs (snoRNA) was identified. The novel snoRNAdisplays structural features typical of C/D box snoRNA fam-ily and possesses a 10-nt-long rRNA antisense element whichis predicted to guide the 2'-O-methylation of the fission yeast 25S rRNA at G940. As expected, the rRNA ribose-methyla-tion site predicted by the novel snoRNA was preciselymapped by a deoxynucleoside triphosphate concentration-dependent primer extension assay. The comparison of func-tional element of guide snoRNAs among eukaryotes reveals that the novel snoRNA is a partial counterpart of the bud-ding yeast snR60 and was termed snR60-II. snR60-II genenested in the intron of a non-coding RNA gene with an un-known function, which is the first example of a yeastsnoRNA encoded in an intron of a non-coding RNA gene.Furthermore, a number of yeast snR60 homologues were also identified from other fungi and fly. Our results reveal thatsnR60 exhibits diverse genomic organization in eukaryotes, implying the high mobility of snR60 gene in the course ofevolution.