I-PpoI, the endonuclease encoded by the group I intron PpLSU3, is expressed from an RNA polymerase I transcript.
PpLSU3, a mobile group I intron in the rRNA genes of Physarum polycephalum, also can home into yeast chromosomal ribosomal DNA (rDNA) (D. E. Muscarella and V. M. Vogt, Mol. Cell. Biol. 13:1023-1033, 1993). By integrating PpLSU3 into the rDNA copies of a yeast strain temperature sensitive for RNA polymerase I, we have shown that the I-PpoI homing endonuclease encoded by PpLSU3 is expressed from an RNA polymerase I transcript. We have also developed a method to integrate mutant forms of PpLSU3 as well as the Tetrahymena intron TtLSU1 into rDNA, by expressing I-PpoI in trans. Analysis of I-PpoI expression levels in these mutants, along with subcellular fractionation of intron RNA, strongly suggests that the full-length excised intron RNA, but not RNAs that are further cleaved, serves as or gives rise to the mRNA.
Lin
J
J
Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853, USA.
Vogt
V M
VM
D000818:Animals; D001665:Binding Sites; D004251:DNA Transposable Elements; D004275:DNA, Ribosomal; D004706:Endodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D007438:Introns; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D010804:Physarum / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012318:RNA Polymerase I / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D013768:Tetrahymena / Q000235:genetics
D004251:DNA Transposable Elements; D004275:DNA, Ribosomal; D012313:RNA; D012318:RNA Polymerase I; D004706:Endodeoxyribonucleases; C064579:I-Ppo endonuclease