H3K56 acetylation modulates genotoxic and fungicidal agent sensitivity in C. albicans. (a) Immunoblot of H3K56ac and total H3 in whole-cell lysates from exponentially growing populations of each strain. (b) Fragmentation spectrum of precursor ion m/z 638.92+ showing the presence of H3K56ac. (c) Extracted ion chromatograms for m/z 638.92+ (H3K56ac) and its deuterated analog m/z 640.42+ (H3K56-D3ac). (d) Stoichiometry of H3K56ac determined by mass spectrometry for histones purified from exponentially growing cells. ε-NH2 of Lys56 is modified with either an acetyl (ac) or a deuterated acetyl (pr) group. (e) Colony formation assays (tenfold serial dilutions of each strain). YPD, control; HU, hydroxyurea; MMS, methyl methane sulfonate; FLC, fluconazole; CSF, caspofungin; MCF, micafungin; NAC, N-acetyl-L-cysteine; VitC, vitamin C.