RTT109 AND Fun30 proteins mediate epigenetic regulation of the DNA damage response pathway in C. albicans

Fun30, an ATP-dependent chromatin remodeller, from S. cerevisiae mediates both regulation of gene expression as well as DNA damage response/repair. In this paper, we have characterized the biochemical and physiological function of Fun30 from the opportunistic fungi, C. albicans. Biochemically, the protein shows DNA-stimulated ATPase activity. Physiologically, the protein co-regulates transcription of RTT109, TEL1, MEC1, and SNF2-genes that encode for proteins involved in DNA damage response and repair pathway. The expression of FUN30, in turn, is regulated by histone H3 acetylation catalysed by Rtt109 encoded by RTT109. The RTT109Hz/FUN30Hz mutant strain shows sensitivity to oxidative stress and resistance to MMS as compared to the wild type strain. Quantitative PCR showed that the sensitivity to oxidative stress results from downregulation of MEC1, RAD9, MRC1 and RAD5 expression; ChIP experiments showed Fun30 but not H3ac regulates the expression of these genes in response to oxidative stress. In contrast, on treatment with MMS, the expression of RAD9 is upregulated and this upregulation is co-regulated by both Fun30 and H3 acetylation catalysed by Rtt109. Thus, Fun30 and H3 acetylation mediate the response of the fungal cell to genotoxic agents in C. albicans by regulating the expression of DNA damage response and repair pathway genes.