Specific interactions between the Candida albicans ABC transporter Cdr1p ectodomain and a D-octapeptide derivative inhibitor.
Overexpression of the Candida albicans ATP-binding cassette transporter CaCdr1p causes clinically significant resistance to azole drugs including fluconazole (FLC). Screening of a ~1.89 × 10(6) member D-octapeptide combinatorial library that concentrates library members at the yeast cell surface identified RC21v3, a 4-methoxy-2,3,6-trimethylbenzenesulphonyl derivative of the D-octapeptide D-NH(2) -FFKWQRRR-CONH(2) , as a potent and stereospecific inhibitor of CaCdr1p. RC21v3 chemosensitized Saccharomyces cerevisiae strains overexpressing CaCdr1p but not other fungal ABC transporters, the C. albicans MFS transporter CaMdr1p or the azole target enzyme CaErg11p, to FLC. RC21v3 also chemosensitized clinical C. albicans isolates overexpressing CaCDR1 to FLC, even when CaCDR2 was overexpressed. Specific targeting of CaCdr1p by RC21v3 was confirmed by spontaneous RC21v3 chemosensitization-resistant suppressor mutants of S. cerevisiae expressing CaCdr1p. The suppressor mutations introduced a positive charge beside, or within, extracellular loops 1, 3, 4 and 6 of CaCdr1p or an aromatic residue near the extracytoplasmic end of transmembrane segment 5. The mutations did not affect CaCdr1p localization or CaCdr1p ATPase activity but some increased susceptibility to the CaCdr1p substrates FLC, rhodamine 6G, rhodamine 123 and cycloheximide. The suppressor mutations showed that the drug-like CaCdr1p inhibitors FK506, enniatin, milbemycin α11 and milbemycin β9 have modes of action similar to RC21v3.
The Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand.
Kyoko
K
Niimi
David R K
DR
Harding
Ann R
AR
Holmes
Erwin
E
Lamping
Masakazu
M
Niimi
Joel D A
JD
Tyndall
Richard D
RD
Cannon
Brian C
BC
Monk
D002176:Candida albicans / Q000201:enzymology*; D025141:Drug Resistance, Fungal; D004791:Enzyme Inhibitors / Q000378:metabolism*; D005656:Fungal Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D009842:Oligopeptides / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013489:Suppression, Genetic
C094693:CDR1 protein, Candida albicans; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D009842:Oligopeptides