Executive Summary : | C. albicans is an opportunistic fungal pathogen exhibiting genomic and morphogenic plasticity which are regulated epigenetically. The ATP driven chromatin remodelers are important epigenetic determinants in Candida biology. In this work, I wish to investigate the role of Rvb proteins in C. albicans. Rvb1 and Rvb2 proteins are the highly conserved AAA+ helicases found in several eukaryotes. Rvb form the important components of different critical complexes like chromatin-remodeling complex INO80, Swr-C and BAF; component of HAT Tip60 complex and R2TP complex in S. cerevisiae and H. sapiens. Polycomb Repressive complex 1 in D. melanogaster contains Rvb2, and Brahma complex contains Rvb1, both the complexes are involved in the regulation of growth and development genes, suggesting the crucial role of Rvb in various cellular processes. Rvb proteins being component of several critical complexes are involved in plethora of cellular functions like DNA double stranded break and UV damage repair, snoRNP biogenesis and assembly, telomere core complex assembly, mitotic spindle assembly and DNA remodeling. They are designated as Reptin and Pontin superfamilies in humans and involved in oncogenesis. Yeast Rvb1 and Rvb2 are ATP-dependent DNA helicases forming heterohexameric complex, recruit Arp5 to assemble a functional Ino80 chromatin remodeling complex. They show sequence similarity to bacterial RuvB proteins, contain the Walker A and Walker B domain at N-terminus. They interact with c-Myc, beta-catenin, E2F1, and ATF2 in higher eukaryotes, and modulate cellular transformation, signalling, apoptosis and response to stress and DNA damage. Rvb1-Rvb2 complex purified from yeast, showed ATP-dependent chromatin remodeling activity in vitro. We hypothesize crucial role of Rvb proteins in DNA damage repair and pathogenicity of the fungi C. albicans. Since C. albicans can accommodate wide range of aneuploidy and genomic rearrangement, it is worth studying the role of Rvb proteins in the genomic plasticity and hence DNA damage repair in C. albicans. The virulent attribute of the fungi is also regulated epigenetically, we hypothesize an important role of Rvb proteins in fungal pathogenesis. Briefly, the knockout of the RVB (identified using in silico method) will be scored for any phenotypic defects. The mutant will be treated with DNA damaging agents, checking for DDR checkpoint activation, recruitment of ds break repair proteins like Rad52 and genomic fragmentation. The mutant will be tested in the mice systemic model of infection to investigate the plausible role in virulence. Spot assay will be done to investigate the role of RVB in stress response. This work will bridge the gap in understanding of the Candida pathogenesis and the genomic integrity. There is a constant need to identify new antifungal physiological target owing to the emerging drug resistant fungi. This study can prove to be the roadmap for further development of antifungal target. |