Salivary histatin 5 induces non-lytic release of ATP from Candida albicans leading to cell death.
Salivary histatins are potent in vitro antifungal proteins and have promise as therapeutic agents against oral candidiasis. We performed pharmacological studies directed at understanding the biochemical basis of Hst 5 candidacidal activity. Three inhibitors of mitochondrial metabolism: carbonyl cyanide p-chlorophenylhydrazone, dinitrophenol, and azide inhibited Hst 5 killing of Candida albicans, while not inhibiting cellular ATP production. In contrast, Hst 5 caused a drastic reduction of C. albicans intracellular ATP content, which was a result of an efflux of ATP. Carbonyl cyanide p-chlorophenylhydrazone, dinitrophenol, and azide inhibited Hst 5-induced ATP efflux, thus establishing a correlation between ATP release and cell killing. Furthermore, C. albicans cells were respiring and had polarized membranes at least 80 min after ATP release, thus implying a non-lytic exit of cellular ATP in response to Hst 5. Based on evidence that transmembrane ATP efflux can occur in the absence of cytolysis through a channel-like pathway and that released ATP can act as a cytotoxic mediator by binding to membrane purinergic receptors, we evaluated whether extracellular ATP released by Hst 5 may have further functional role in cell killing. Consistent with this hypothesis, purinergic agonists BzATP and adenosine 5'O-(thiotriphosphate) induced loss of C. albicans cell viability and purinergic antagonists prevented Hst 5 killing.
Koshlukova
S E
SE
Department of Oral Biology, School of Dental Medicine, State University of New York at Buffalo, Buffalo, New York 14214, USA.
Lloyd
T L
TL
Araujo
M W
MW
Edgerton
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000378:metabolism*; D001386:Azides / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000378:metabolism*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D004140:Dinitrophenols / Q000494:pharmacology; D054808:Histatins; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D010101:Oxygen Consumption; D011983:Receptors, Purinergic / Q000378:metabolism; D012471:Salivary Proteins and Peptides / Q000378:metabolism*; D014475:Uncoupling Agents / Q000494:pharmacology
D000935:Antifungal Agents; D001386:Azides; D004140:Dinitrophenols; C068075:HTN3 protein, human; D054808:Histatins; D011983:Receptors, Purinergic; D012471:Salivary Proteins and Peptides; D014475:Uncoupling Agents; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000255:Adenosine Triphosphate