Mutations of RNA polymerase II activate key genes of the nucleoside triphosphate biosynthetic pathways.
The yeast URA2 gene, encoding the rate-limiting enzyme of UTP biosynthesis, is transcriptionally activated by UTP shortage. In contrast to other genes of the UTP pathway, this activation is not governed by the Ppr1 activator. Moreover, it is not due to an increased recruitment of RNA polymerase II at the URA2 promoter, but to its much more effective progression beyond the URA2 mRNA start site(s). Regulatory mutants constitutively expressing URA2 resulted from cis-acting deletions upstream of the transcription initiator region, or from amino-acid replacements altering the RNA polymerase II Switch 1 loop domain, such as rpb1-L1397S. These two mutation classes allowed RNA polymerase to progress downstream of the URA2 mRNA start site(s). rpb1-L1397S had similar effects on IMD2 (IMP dehydrogenase) and URA8 (CTP synthase), and thus specifically activated the rate-limiting steps of UTP, GTP and CTP biosynthesis. These data suggest that the Switch 1 loop of RNA polymerase II, located at the downstream end of the transcription bubble, may operate as a specific sensor of the nucleoside triphosphates available for transcription.
Kwapisz
Marta
M
CEA, iBiTec-S, Service de Biologie Intégrative et Génétique Moléculaire, Gif-sur-Yvette, France.
Wery
Maxime
M
Després
Daphné
D
Ghavi-Helm
Yad
Y
Soutourina
Julie
J
Thuriaux
Pierre
P
Lacroute
François
F
D001221:Aspartate Carbamoyltransferase / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D015966:Gene Expression Regulation, Fungal; D007168:IMP Dehydrogenase / Q000235:genetics; D008954:Models, Biological; D009154:Mutation; D009705:Nucleosides / Q000737:chemistry*; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009705:Nucleosides; C065682:PPR1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C110837:URA2 protein, S cerevisiae; C477283:IMD2 protein, S cerevisiae; D007168:IMP Dehydrogenase; D001221:Aspartate Carbamoyltransferase; D012319:RNA Polymerase II; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)