Antifungal Effect of <i>Arabidopsis</i> SGT1 Proteins via\nMitochondrial Reactive Oxygen Species

The highly conserved SGT1 (suppressor\nof the G2 alleles of skp1) proteins from <i>Arabidopsis</i> are known to contribute to plant resistance to pathogens. While\nSGT1 proteins respond to fungal pathogens, their antifungal activity\nis not reported and the mechanism for this inhibition is not well\nunderstood. Therefore, recombinant <i>Arabidopsis</i> SGT1\nproteins were cloned, expressed, and purified to evaluate their antifungal\nactivity, resulting in their potent inhibition of pathogen growth.\nDye-labeled proteins are localized to the cytosol of <i>Candida\nalbicans</i> cells without the disruption of the cell membrane.\nMoreover, we showed that entry of the proteins into <i>C. albicans</i> cells resulted in the accumulation of reactive oxygen species (ROS)\nand cell death via altered mitochondrial potential. Morphological\nchanges of <i>C. albicans</i> cells in the presence of proteins\nwere visualized by scanning electron microscopy. Our data suggest\nthat AtSGT1 proteins play a critical role in plant resistance to pathogenic\nfungal infection and they can be classified to a new plant antifungal\nprotein.