Arabidopsis Mediator subunit 17 connects transcription with DNA repair after UV-B exposure

GIUSTOZZI, MARISOL; FREYTES, SANTIAGO N.; CERDÁN, PABLO; PAULA CASATI

Congreso; THE 31st INTERNATIONAL CONFERENCE ON ARABIDOPSIS RESEARCH; 2021

Mediator subunit 17 (MED17) is a subunit of the Mediator complex and regulates transcription initiation in eukaryotic organisms. In yeast and humans, MED17 also participates in DNA repair,physically interacting with proteins in Nucleotide Excision DNA Repair. Thus, we analyzed the role of MED17 in Arabidopsis plants exposed to UV-B radiation. We compared med17 mutanttranscriptome to that of WT plants; results showed that almost one third of transcripts with altered expression in med17 plants are also changed by UV-B exposure in WT plants. To validate the roleof MED17 in UV-B irradiated plants, plant responses to UV-B were analyzed, including flowering time, DNA damage accumulation and programmed cell death in the meristematic cells of the roottips. Our results show that med17 mutants have altered responses to UV-B; and in particular, we demonstrated that MED17 participates in various aspects of the DNA damage response (DDR).Increased sensitivity to DDR after UV-B in med17 plants can be due to altered regulation of UV-B responsive transcripts; but additionally MED17 directly interacts with DNA repair proteins,suggesting a direct role of this Mediator subunit during repair. Together, the data demonstrates that MED17 is an important regulator of the DDR after UV‐B radiation in Arabidopsis plants