title: Released ATP is an extracellular cytotoxic mediator in salivary histatin 5-induced killing of Candida albicans.
abstract: Salivary histatins (Hsts) are antifungal peptides with promise as therapeutic agents against candidiasis. Hst 5 kills the fungal pathogen Candida albicans via a mechanism that involves release of cellular ATP in the absence of cytolysis. Here we demonstrate that released ATP has a further role in Hst 5 killing. Incubation of the cells with ATP analogues induced cell death, and addition of the ATP scavenger apyrase to remove extracellular ATP released during Hst 5 treatment resulted in a reduction in cell killing. Experiments using anaerobically grown C. albicans with decreased susceptibility to Hst 5 confirmed that depletion of cellular ATP as a result of ATP efflux was not sufficient to cause cell death. In contrast to Hst-susceptible aerobic cultures, anaerobically grown cells were not killed by exogenously applied ATP. These findings established that Hst binding, subsequent entry into the cells, and ATP release precede the signal for cytotoxicity, which is mediated by extracellular ATP. In a higher-eukaryote paradigm, released ATP acts as a cytotoxic mediator by binding to membrane nucleotide P2X receptors. Based on a pharmacological profile and detection of a C. albicans 60-kDa membrane protein immunoreactive with antibody to P2X(7) receptor, we propose that released ATP in response to Hst 5 activates candidal P2X(7)-like receptors to cause cell death.
authors.affiliation: Department of Oral Biology, School of Dental Medicine, State University of New York at Buffalo, Buffalo, New York 14214, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Koshlukova
authors.forename: M W
authors.initials: MW
authors.lastname: Araujo
authors.forename: D
authors.initials: D
authors.lastname: Baev
authors.forename: M
authors.initials: M
authors.lastname: Edgerton
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology*; D000595:Amino Acid Sequence; D000693:Anaerobiosis; D000935:Antifungal Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects*; D054808:Histatins; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D058910:Purinergic P2 Receptor Agonists; D012471:Salivary Proteins and Peptides / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; C068075:HTN3 protein, human; D054808:Histatins; D058910:Purinergic P2 Receptor Agonists; D012471:Salivary Proteins and Peptides; D000255:Adenosine Triphosphate