ROLES OF THE SUBUNIT 17 OF MEDIATOR COMPLEX IN THE UV-B INDUCED DNA DAMAGE RESPONSE

MARISOL GIUSTOZZI; A. JASKOLOWSKI; P. CERDÁN; PAULA CASATI

Congreso; LIV Reunión SAIB 2018; 2018

Mediator complex is multi-subunit protein, conserved throughout eukaryotes; which functions as a molecular bridge between gene specifictranscription factors bound at enhancers and RNA polymerase II. Several reports demonstrate that the Mediator complex in yeast acts asregulatory protein linking transcription with DNA repair. In particular, in yeast and humans, mutants in the subunit 17 of the Mediator complexhave defects in the nucleotide excision repair (NER) system. In Arabidopsis thaliana, mediator is composed by 34 subunits and acts as a signalintegrator. In recent years, ozone depletion in the stratosphere has resulted in an increase in ultraviolet-B radiation levels at the earth?s surface,causing DNA lesions, induction of stress responses and inhibition of photosynthesis. Repair of DNA damage is essential to maintain thegenomic integrity. Thus, the aim of this work is to explore the participation of Mediator in DNA damage responses induced by UV-B radiationin A. thaliana plants by using med17 mutants and transgenic plants overexpressing AtMED17. Our results show that med17 plants accumulatemore damaged DNA after UV-B exposure in the absence of white light than Wild Type Col-0 plants. When DNA damage level is not repaired incells, programmed death cell (PDC) is triggered, consequently, our interest is to analyze if MED17 is involved in PDC after UV-B. Therefore,med17 mutants show a lower number of meristematic death cells in root tips after UV-B exposure, while the opposite was observed inoverexpressing MED17 roots. Together, our results suggest that AtMED17 has an important role in the DNA damage response in Arabidopsis.