R-loops do not accumulate in transcription-defective hpr1-101 mutants: implications for the functional role of THO/TREX.
To get further insight into the effect that THO/TREX and R-loops have in transcription-associated recombination and transcription, we analyzed the ability to form R-loops of hpr1-101, a THO mutation that impairs transcription and mRNP biogenesis without triggering hyper-recombination. Human AID, a cytidine deaminase that acts on ssDNA displaced by RNA-DNA hybrids, strongly induced both hyper-recombination and hyper-mutation in hpr1-101, similar to hpr1Delta mutants. However, in contrast to hpr1Delta, AID-induced mutations in hpr1-101 occur at similar frequencies in both the transcribed and non-transcribed strands, implying that the enhanced AID action in these mutants is not caused by co-transcriptional R-loops. These results indicate for the first time that THO has a transcriptional function that is not mediated by R-loops, providing a new perspective for the understanding of the coupling of transcription with mRNP biogenesis and export.
Gómez-González
Belén
B
Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, 41092 Sevilla, Spain.
Aguilera
Andrés
A
D000483:Alleles; D003564:Cytidine Deaminase / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000032:analysis; D017930:Genes, Reporter; D006801:Humans; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D016601:RNA-Binding Proteins / Q000378:metabolism; D011995:Recombination, Genetic; D016914:Ribonuclease H / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
D004277:DNA, Single-Stranded; C063494:HPR1 protein, S cerevisiae; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C026452:messenger ribonucleoprotein; D016914:Ribonuclease H; C078856:ribonuclease HI; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase