Identification of polymorphic mutant alleles of CaMDR1 , a major facilitator of Candida albicans which confers multidrug resistance, and its in vitro transcriptional activation

Abstract

CaMDR1 (Candida albicans Multi Drug Resistance) encodes a major facilitator whose expression in Saccharomyces cerevisiae confers resistance to several unrelated drugs. We describe here the identification and molecular characterization of seven mutant alleles of CaMDR1 (CaMDR1-1 to 1-7). The complete sequencing of CaMDR1 alleles revealed several in-frame point mutations leading to a change in amino-acid residues where insertion/replacement of an aspartate residue in a serine-asparagine-aspartate-rich domain was most noteworthy. Interestingly, these alleles showed a distinct drug resistance profile. The expression of CaMDR1, or of its alleles, in C. albicans cells was enhanced by benomyl, methotrexate and several other unrelated drugs, and was more pronounced in at least one of the azole-resistant clinical isolates.

Identification of promoter elements responsible for the regulation of MDR1 from Candida albicans, a major facilitator transporter involved in azole resistance

“…Upregulation of MDR1 can occur in C. albicans azoleresistant strains or in azole-susceptible strains exposed to diverse drugs including benomyl and H 2 O 2 (Gupta et al, 1998;Harry et al, 2005). Therefore we tested the response of the reporter to a panel of compounds known as inducers of MDR1.…”

“…However, a dramatic transient upregulation of MDR1 can be observed in azole-susceptible strains after treatment with toxic hydrophobic agents (benomyl, methotrexate, 4-NQO, o-phenanthroline), oxidizing agents [diamide, H 2 O 2 , tert-butyl hydrogen peroxide (T-BHP) and diethylmaleate] and the alkylating agent methyl methanesulfonate (Gupta et al, 1998;Harry et al, 2005). Clinical isolates with increased MDR1 expression have not undergone amplification of the MDR1 gene (Wirsching et al, 2000a).…”

ABC transporters Cdr1p, Cdr2p and Cdr3p of a human pathogen Candida albicans are general phospholipid translocators

“…The resistance to azoles in C. albicans, was earlier thought to occur primarily through an alteration or an overexpression of the 14a-lanosterol demethylase (P45014DM) involved in sterol biosynthesis (Lamb et al, 1997;White, 1997). However, the characterization of the first ATP-binding cassette (ABC) protein Cdr1p (Candida drug resistance) by us Krishnamurthy et al, 1998a, b, c;Prasad et al, 1995a;Smriti et al, 1999) and the subsequent identification of other efflux pumps (Balan et al, 1997;Sanglard et al, 1997Sanglard et al, , 1999Calabrese et al, 2000;Franz et al, 1998) and their overexpression in azole-resistant clinical isolates has led to the suggestion that these transporters represent another mechanism involved in multidrug resistance (MDR) scenario of C. albicans (Balan et al, 1997;Sanglard et al, 1997Sanglard et al, , 1999Gupta et al, 1998;Krishnamurthy et al, 1998;Smriti et al, 1999;Calabrese et al, 2000;Franz et al, 1998). In spite of the widespread occurrence of the MDR genes in C. albicans, the molecular mechanisms of their function and the regulation of their expression is yet to be understood (Prasad et al, 1995a.…”

The SCR1 gene from Schwanniomyces occidentalis encodes a highly hydrophobic polypeptide, which confers ribosomal resistance to cycloheximide

“…The highest similarity, extending over the complete sequence, was with known or presumptive yeast transmembrane proteins including those encoded by the MDR1 gene responsible for fluconazole resistance in C. dubliniensis (Moran et al, 1998), the MDR1-6 mutant allele of the CaMDR1 gene from C. albicans, which is responsible for resistance to benomyl, methotrexate and several other unrelated drugs (Gupta et al, 1998), CYH R of C. maltosa, which confers resistance to cyh (Sasnauskas et al, 1992), and MDR1, responsible for fluconazole resistance in C. tropicalis (Barchiesi et al, 2000). The identity and similarity were 57-55% and 69-68%, respectively.…”

“…The genome sequence from S. cerevisiae has revealed the presence of as many as 28 ORFs homologous to either the ABC or the MFS family (Goffeau et al, 1997). Yeast multidrug transporters include the ABCs protein CDR1-3 from Candida albicans (Sanglard et al, 1997;Balan et al, 1997) and the MSF BEN r (CaMDR1) that renders cells resistant to cyh, benomyl, methotrexate, 4-nitro-quinoline-N-oxide, or terbinafine (Ben-Yaacov et al, 1994;Goldway et al, 1995;Sanglard et al, 1997;Gupta et al, 1998). The C. maltosa CYR R and the C. dubliniensis CdMDR1, homologous to CaMDR1, confer resistance to cyh (Sasnauskas et al, 1992) or to fluconazole, cyh, benomyl or sulphometuron methyl, respectively (Moran et al, 1998).…”