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.
Nabavi
Sadeq
S
Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G2W1.
Nazar
Ross N
RN
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