The antifungal plant defensin RsAFP2 from radish induces apoptosis in a metacaspase independent way in Candida albicans

Abstract 

We show that the antifungal plant defensin Raphanus sativus antifungal protein 2 (RsAFP2) from radish induces apoptosis and concomitantly triggers activation of caspases or caspase-like proteases in the human pathogen Candida albicans. Furthermore, we demonstrate that deletion of C. albicans metacaspase 1, encoding the only reported (putative) caspase in C. albicans, significantly affects caspase activation by the apoptotic stimulus acetic acid, but not by RsAFP2. To our knowledge, this is the first report on the induction of apoptosis with concomitant caspase activation by a defensin in this pathogen. Moreover, our data point to the existence of at least two different types of caspases or caspase-like proteases in C. albicans.

Abbreviations: CaMCA1, Candida albicans metacaspase 1, CFU, colony forming unit, DHE, dihydroethidium, GlcCer, glucosylceramide, PI, propidium iodide, PS, phosphatidylserine, ROS, reactive oxygen species, RsAFP2, Raphanus sativus antifungal protein 2, TUNEL, terminal transferase-mediated dUTP nick end labeling, z-VAD-FMK, carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone

Keywords: Apoptosis, Plant defensin, Antifungal, Mode of action, Metacaspase, Candida albicans metacaspase 1