The sequence of U3 from Schizosaccharomyces pombe suggests structural divergence of this snRNA between metazoans and unicellular eukaryotes.
We have cloned and sequenced one of the two genes encoding a 255 nucleotide small nuclear RNA from the fission yeast Schizosaccharomyces pombe. Based on the presence of four regions of primary sequence conservation and a predicted secondary structure similar to that previously proposed for human U3, we conclude that this molecule is the fission yeast homologue of this mammalian snRNA. The 5' one-third of fission yeast U3 is, however, unable to form a single stable hairpin as proposed for this region of the human RNA, but rather folds into two stem-loop structures. By analogy to fission yeast U3, we propose revised secondary structures containing two hairpins for this portion of the U3-like snRNAs from Saccharomyces cerevisiae and Dictyostelium discoideum. Thus, our data suggest that the structure of U3 snRNA has diverged in lower and higher eukaryotes.
Porter
G L
GL
Department of Biochemistry, University of Illinois, Urbana 61801.
Brennwald
P J
PJ
Holm
K A
KA
Wise
J A
JA
D001483:Base Sequence; D005075:Biological Evolution; D005800:Genes, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012342:RNA, Small Nuclear / Q000235:genetics*; D015183:Restriction Mapping; D004718:Saccharomycetales / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics*; D013045:Species Specificity
D012342:RNA, Small Nuclear