Histatin 3-mediated killing of Candida albicans: Effect of extracellular salt concentration on binding and internalization

Yanying Xu, Indu Ambudkar, Hisako Yamagishi, William Swaim, Thomas J. Walsh, Brian C. O'Connell

Research output: Contribution to journalArticle

Abstract

Human saliva contains histidine-rich proteins, histatins, which have antifungal activity in vitro. The mechanism by which histatins are able to kill Candida albicans may have clinical significance but is currently unknown. Using radiolabeled histatin 3, we show that the protein binds to C. albicans spheroplasts in a manner that is dependent on time and concentration. Binding to the spheroplasts was saturable and could be competed with unlabeled histatin 3. A single histatin 3 binding site with a K(d) = 5.1 μM was detected. Histatin 3 binding resulted in potassium and magnesium efflux, predominantly within the first 30 min of incubation. Studies with fluorescent histatin 3 demonstrate that the protein is internalized by C. albicans and that translocation of histatin inside the cell is closely associated with cell death. Histatin binding, internalization, and cell death are accelerated in low-ionic-strength conditions. Indeed, a low extracellular salt concentration was essential for cell death to occur, even when histatin 3 was already bound to the cell. The interaction of histatin 3 with C. albicans, and subsequent cell death, is inhibited at low temperature. These results demonstrate that the candidacidal activity of histatin 3 is not due exclusively to binding at the cell surface but also involves subsequent interactions with the cell.

Original languageEnglish (US)
Pages (from-to)2256-2262
Number of pages7
JournalAntimicrobial agents and chemotherapy
Volume43
Issue number9
StatePublished - Sep 1999

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ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

Cite this

Xu, Y., Ambudkar, I., Yamagishi, H., Swaim, W., Walsh, T. J., & O'Connell, B. C. (1999). Histatin 3-mediated killing of Candida albicans: Effect of extracellular salt concentration on binding and internalization. Antimicrobial agents and chemotherapy, 43(9), 2256-2262.