Nucleotide excision repair and the degradation of RNA pol II by the Caenorhabditis elegans XPA and Rsp5 orthologues, RAD-3 and WWP-1.
The Caenorhabditis elegans rad-3 gene was identified in a genetic screen for radiation sensitive (rad) mutants. Here, we report that the UV sensitivity of rad-3 mutants is caused by a nonsense mutation in the C. elegans orthologue of the human nucleotide excision repair gene XPA. We have used the xpa-1/rad-3 mutant to examine how a defect in nucleotide excision repair (NER) perturbs development. We find that C. elegans carrying a mutation in xpa-1/rad-3 are hypersensitive and hypermutable in response to UV irradiation, but do not display hypersensitivity to oxidative stress or show obvious developmental abnormalities in the absence of UV exposure. Consistent with these observations, non-irradiated xpa-1 mutants have a similar lifespan as wild type. We further show that UV irradiated xpa-1 mutants undergo a stage-dependent decline in growth and survival, which is associated with a loss in transcriptional competence. Surprisingly, transcriptionally quiescent dauer stage larvae are able to survive a dose of UV irradiation, which is otherwise lethal to early stage larvae. We show that the loss of transcriptional competence in UV irradiated xpa-1 mutants is associated with the degradation of the large RNA polymerase II (RNA pol II) subunit, AMA-1, and have identified WWP-1 as the putative E3 ubiquitin ligase mediating this process. The absence of wwp-1 by itself does not cause sensitivity to UV irradiation, but it acts synergistically with a mutation in xpa-1 to enhance UV hypersensitivity.
Astin
Jonathan W
JW
Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol, UK.
O'Neil
Nigel J
NJ
Kuwabara
Patricia E
PE
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017173:Caenorhabditis elegans / Q000187:drug effects / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000235:genetics* / Q000502:physiology; D040461:Gene Components; D008136:Longevity / Q000235:genetics; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000235:genetics; D010269:Paraquat / Q000633:toxicity; D034622:RNA Interference; D012319:RNA Polymerase II / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic / Q000235:genetics / Q000528:radiation effects*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays; D051760:Xeroderma Pigmentosum Group A Protein / Q000235:genetics / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D009841:Oligonucleotides; D051760:Xeroderma Pigmentosum Group A Protein; C413402:wwp-1 protein, C elegans; D044767:Ubiquitin-Protein Ligases; D012319:RNA Polymerase II; D010269:Paraquat