Histatin 5 and derivatives. Their localization and effects on the ultra-structural level

Histatins, a family of cationic peptides present in saliva, are active against the opportunistic yeast Candida albicans. The mechanism of action is still unclear. Histatin 5 and more potent synthetic variants, dhvar4 and dhvar5, were used to study localization and effects on morphology on the ultra-structural level. Although all peptides induced leakage, no association with the plasma membrane, indicative for permanent pores, was observed with immuno-gold-labeling. Freeze-fracturing showed severe changes of the plasma membrane. Together with, for the dhvars, the loss of intracellular integrity, this suggests that leakage may be a secondary effect rather than an effect of formation of permanent pores.