A protein complex containing Tho2, Hpr1, Mft1 and a novel protein, Thp2, connects transcription elongation with mitotic recombination in Saccharomyces cerevisiae

Transcription-induced recombination has been reported in all organisms from bacteria to mammals. We have shown previously that the yeast genes HPR1 an d THO2 may be keys to the understanding of transcription-associated recombi nation, as they both affect transcription elongation and hyper-recombinatio n in a concerted manner. Using a yeast strain that has the wild-type THO2 g ene replaced by one encoding a His(6)-HA-tagged version, we have isolated a n oligomeric complex containing four proteins: Tho2, Hpr1, Mft1 and a novel protein that we have named Thp2, We have reciprocally identified a complex containing Hpr1, Tho2 and Mft1 using anti-Mft1 antibodies in immunoprecipi tation experiments. The protein complex is mainly nuclear; therefore, Tho2 and Hpr1 are physically associated, Like hpr1 Delta and tho2 Delta cells, m ft1 Delta and thp2 Delta cells show mitotic hyper-recombination and impaire d transcription elongation, in particular, through the bacterial lacZ seque nce. Hyper-recombination conferred by mft1 Delta and thp2 Delta is only obs erved in DNA regions under transcription conditions. We propose that this p rotein complex acts as a functional unit connecting transcription elongatio n with the incidence of mitotic recombination.