Relative rates of transport of peptidyl drugs by Candida albicans

The mechanism of anticandidal action of novel synthetic dipeptides containing N3-(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid (FMDP) residues was shown to be consistent with the "warhead delivery" concept. FMDP dipeptides were shown to be transported into Candida albicans cells by the di-tripeptide permease and subsequently hydrolyzed by intracellular peptidases, especially aminopeptidase. The anticandidal activity of the particular FMDP dipeptide was influenced by the rate of its transport and, to a lower extent, by the intracellular cleavage rate. A high transport rate accompanied by a high cleavage rate resulted in the high anticandidal activity of L-norvalyl-FMDP. The strong growth-inhibitory effect of this compound was the consequence of inhibition of the enzyme glucosanine-6-phosphate synthase by the released FMDP. The action of L-norvalyl-FMDP on exponentially growing C. albicans cells resulted in a sharp decrease of incorporation of 14C label from [14C]glucose into chitin, mannoprotein, and glucan. This effect, as well as the growth-inhibitory effect, was fully reversed by exogenous N-acetyl-D-glucosamine. Glucosamine-6-phosphate synthase was proved to be the only essential target for FMDP dipeptides. Scanning electron microscopy of C. albicans cells treated with L-norvalyl-FMDP revealed highly distorted, wrinkled, and collapsed forms. Cells formed long, bulbous chains, and partial lysis occurred.

Section: Discussionmentioning

confidence: 54%

Mechanism of action of anticandidal dipeptides containing inhibitors of glucosamine-6-phosphate synthase

Milewski

Andruszkiewicz

Kasprzak

et al. 1991

“…In consequence, the biosynthesis of the glucosaminecontaining cell wall macromolecules, chitin and mannoprotein, is inhibited (24). It was also evidenced that the relative rates of uptake of an oligopeptide antifungal agents determine their anticandidal activity (22). Therefore, trying to find an explanation for unusual susceptibility of JGCDR1 yeast to FMDPpeptides, we determined the uptake rates of these compounds and a few oligopeptides built exclusively of proteinogenic amino acids by JG436 transformants cells.…”

Section: Resultsmentioning

confidence: 99%

Unusual Susceptibility of a Multidrug-Resistant Yeast Strain to Peptidic Antifungals

Milewski

Mignini

Prasad

et al. 2001

The susceptibility of Saccharomyces cerevisiae JG436 multidrug transporter deletion mutant, Deltapdr5, to several antifungal agents was compared to that of JG436-derived JGCDR1 and JGCaMDR1 transformants, harboring the CDR1 and CaMDR1 genes, encoding the main drug-extruding membrane proteins of Candida albicans. The JGCDR1 and JGCaMDR1 yeasts demonstrated markedly diminished susceptibility to the azole antifungals, terbinafine and cycloheximide, while that to amphotericin B was unchanged. Surprisingly, JGCDR1 but not JGCaMDR1 cells showed enhanced susceptibility to peptidic antifungals, rationally designed compounds containing inhibitors of glucosamine-6-phosphate synthase. It was found that these antifungal oligopeptides, as well as model oligopeptides built of proteinogenic amino acids, were not effluxed from JGCDR1 cells. Moreover, they were taken up by these cells at rates two to three times higher than by JG436. The tested oligopeptides were rapidly cleaved to constitutive amino acids by cytoplasmic peptidases. Studies on the mechanism of the observed phenomenon suggested that an additive proton motive force generated by Cdr1p stimulated uptake of oligopeptides into JGCDR1 cells, thus giving rise to the higher antifungal activity of FMDP [N(3)-(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid]-peptides.

“…The antifungal action of all oligopeptide and amino acid antifungals used in this study is antagonized by proteinogenic oligopeptides or amino acids, respectively, which compete for uptake into the fungal cells via oligopeptide or amino acid permeases (4,8,21,26,28,43,46,47). To test whether the presence and activity of drug-effluxing transporters affected oligopeptide or amino acid transport, the uptake rates of these compounds, alanine, Ala-Ala, and Ala-Ala-Ala, were determined.…”

Section: Resultsmentioning

confidence: 99%

“…Other oligopeptides, like compounds 1 to 8, are cleaved intracellularly by peptidases, and the released enzyme inhibitor is then able to reach its target (3,4,21,28,29,43). The uptake of antifungal oligopeptides, rather than their intracellular cleavage, appears to be the rate-limiting step that determines their potency (25,26). Thus, the relatively slow accumulation of oligopeptides 1 to 9 by the AD cells, a substantial enhancement of this uptake in AD-derived mutants overexpressing CDR1 or CDR2 and a good match between the enhanced transport rates and the increased antifungal activity, are consistent with the enhanced susceptibilities to oligopeptide antifungals being due to accelerated uptake.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Susceptibility to Antifungal Oligopeptides in Yeast Strains Overexpressing ABC Multidrug Efflux Pumps

Wakieć

Gabriel

Prasad

et al. 2008

The susceptibility to several oligopeptide and amino acid antifungals of a Saccharomyces cerevisiae strain carrying multiple deletions in yeast multidrug resistance genes was compared to transformants containing the CDR1, CDR2, or MDR1 genes that encode the major Candida albicans drug efflux pumps. Recombinant yeast strains overexpressing Cdr1p and Cdr2p showed enhanced susceptibilities to all tested oligopeptide antifungals. The enhanced susceptibilities of multidrug-resistant yeast strains to oligopeptide antifungals corresponded to higher rates of oligopeptide uptake. Yeast cells overexpressing Cdr1p or Cdr2p effluxed protons at higher rates than the reference cells lacking these ABC transporters. An increased plasma membrane electrochemical gradient caused by the functional overexpression of Cdr1p or Cdr2p appeared to increase cellular susceptibility to oligopeptide antifungals by stimulating their uptake via oligopeptide permeases.