More than half of yeast U1 snRNA is dispensable for growth.
Yeast U1 snRNA (568 nucleotides) is 3.5-fold larger than its mammalian counterpart (164 nucleotides) and contains apparent sequence homology only at the 5' and 3' ends. We have used deletion analysis to determine whether the yeast-specific U1 sequences play essential roles in vivo. Yeast cells carrying a deletion of more than 60% (355 nucleotides) of the single-copy U1 gene are viable, though slow-growing, while a deletion of 316 nucleotides allows essentially wild-type growth. The boundaries of the viable deletions define a dispensable internal domain which comprises sequences unique to yeast. In contrast, the essential 5' and 3' terminal domains correspond to phylogenetically conserved sequences and/or structures previously implicated in RNA:RNA and RNA:protein interactions. The minimal essential sequences of yeast U1 can be drawn in a secondary structure which resembles metazoan U1 in four of seven structural domains.
Siliciano
P G
PG
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Kivens
W J
WJ
Guthrie
C
C
D001483:Base Sequence; D015152:Blotting, Northern; D005800:Genes, Fungal; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010641:Phenotype; D012326:RNA Splicing; D012331:RNA, Fungal / Q000502:physiology; D012342:RNA, Small Nuclear / Q000502:physiology*; D015003:Yeasts / Q000235:genetics / Q000254:growth & development*
D012331:RNA, Fungal; D012342:RNA, Small Nuclear