Yeast spt6-140 mutation, affecting chromatin and transcription, preferentially increases recombination in which Rad51p-mediated strand exchange is dispensable.
We have shown that the spt6-140 and spt4-3 mutations, affecting chromatin structure and transcription, stimulate recombination between inverted repeats by a RAD52-dependent mechanism that is very efficient in the absence of RAD51, RAD54, RAD55, and RAD57. Such a mechanism of recombination is RAD1-RAD59-dependent and yields gene conversions highly associated with the inversion of the repeat. The spt6-140 mutation alters transcription and chromatin in our inverted repeats, as determined by Northern and micrococcal nuclease sensitivity analyses, respectively. Hyper-recombination levels are diminished in the absence of transcription. We believe that the chromatin alteration, together with transcription impairment caused by spt6-140, increases the incidence of spontaneous recombination regardless of whether or not it is mediated by Rad51p-dependent strand exchange. Our results suggest that spt6, as well as spt4, primarily stimulates a mechanism of break-induced replication. We discuss the possibility that the chromatin alteration caused by spt6-140 facilitates a Rad52p-mediated one-ended strand invasion event, possibly inefficient in wild-type chromatin. Our results are consistent with the idea that the major mechanism leading to inversions might not be crossing over but break-induced replication followed by single-strand annealing.
Malagón
F
F
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Avd. Reina Mercedes 6, 41012 Seville, Spain.
Aguilera
A
A
D015152:Blotting, Northern; D015139:Blotting, Southern; D002843:Chromatin / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005838:Genotype; D056488:Histone Chaperones; D006836:Hydro-Lyases / Q000235:genetics; D008957:Models, Genetic; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D051135:Rad51 Recombinase; D011995:Recombination, Genetic; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors
D002843:Chromatin; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D056488:Histone Chaperones; D009687:Nuclear Proteins; C080991:SPT4 protein, S cerevisiae; C065456:SPT6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035602:Transcriptional Elongation Factors; D004247:DNA; D051135:Rad51 Recombinase; D006836:Hydro-Lyases; C021434:imidazoleglycerolphosphate dehydratase