Cleavage-induced termination in U2 snRNA gene expression.
The maturation of many small nuclear RNAs is dependent on RNase III-like endonuclease mediated cleavage, which generates a loading site for the exosome complex that trims the precursor at its 3' end. Using a temperature sensitive Pac1 nuclease, here we show that the endonuclease cleavage is equally important in terminating the transcription of the U2 snRNA in Schizosaccharomyces pombe. Using a temperature sensitive Dhp1p 5'-->3' exonuclease, we demonstrate that it also is an essential component of the termination pathway. Taken together the results support a "reversed torpedoes" model for the termination and maturation of the U2 snRNA; the Pac1 endonuclease cleavage provides entry sites for the 3' and 5' exonuclease activities, leading to RNA maturation in one direction and transcript termination in the other.
Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G2W1.
Sadeq
S
Nabavi
Ross N
RN
Nazar
D001483:Base Sequence; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D012342:RNA, Small Nuclear / Q000235:genetics* / Q000378:metabolism; D012568:Schizosaccharomyces / Q000201:enzymology / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D012342:RNA, Small Nuclear; D029702:Schizosaccharomyces pombe Proteins; C405484:U2 small nuclear RNA; D004722:Endoribonucleases; C499540:pac1 protein, S pombe