Validation of Nri1/Nri2 physical interaction with the Candida albicans RSC complex

Regulation of gene expression programs is crucial for the survival of microbial pathogens in host environments and for their ability to cause disease. In this study, we investigated the epigenetic regulator RSC (Remodels the Structure of Chromatin) in the most prevalent human fungal pathogen Candida albicans (CaRSC). To precisely determine the composition of the CaRSC complex, we immunopurified Myc-tagged Sth1, the core catalytic subunit of the CaRSC complex encoded by C3_02490C and identified its physical interactors using high-resolution tandem mass spectrometry (LC-MS/MS). Strikingly, we identified two novel hitherto uncharacterized proteins that co-purified with Sth1, C2_01370p (Nri1) and C1_01800p (Nri2), whose homologs are annotated only in the CTG clade of fungi. Here, we performed reciprocal co-immunoprecipitations of Myc-tagged Nri1 and Nri2 followed by LC-MS/MS to validate these interactions. For each condition, biological duplicates were analyzed.