Chemoproteomic Profiling of C. albicans for Characterization of Antifungal Kinase Inhibitors

Candida albicans is a
major cause
of systemic candidiasis, a severe fungal infection with a ∼40%
mortality rate. Yck2, a casein kinase 1 (CK1) in C.
albicans, is targeted by antifungal inhibitors YK-I-02
(YK) and MN-I-157 (MN). Using multiplexed inhibitor beads and mass
spectrometry (MIB/MS), the selectivity of these inhibitors was determined
across the fungal kinome. The MIB matrix captured 89% of C. albicans protein kinases, revealing that YK and
MN selectively engage three CK1 homologues (Yck2, Yck22, and Hrr25)
and a human p38α homologue (Hog1). Chemoproteomics using a custom
MN-kinobead confirmed the remarkable fungal kinome selectivity. To
identify new Yck2 inhibitors with selectivity over Hog1, 13 human
CK1 inhibitors were screened, leading to the discovery of a new chemotype
with antifungal activity. These findings highlight the utility of
MIB/MS in profiling nonhuman kinomes and developing selective fungal
kinase inhibitors as antimicrobial agents.