Milbemycin A4 oxime as a probe of azole transport in Candida glabrata

Bryan Walker, Koichi Izumikawa, Huie Fung Tsai, John E. Bennett

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Azole resistance in Candida glabrata, a pathogenic yeast, has prompted studies of compounds that have therapeutic potential by reversing azole resistance. Milbemycin A4 oxime blocked azole efflux and enhanced azole susceptibility fourfold in 28 clinical isolates of C. glabrata. Specificity of the milbemycin A4 oxime effect depended on the drug transporter and the substrate being effluxed. The major effect of milbemycin A4 oxime was inhibition of azole and rhodamine 6G efflux by the ATP-binding cassette (ABC) transporters CgCDR1 and PDH1. Milbemycin A4 oxime effect did not extend to oligomycin, transported by the ABC transporter YOR1 or to benomyl, transported by the major facilitator superfamily transporter, CgFLR1. Milbemycin A4 oxime did not suppress transcription of CgCDR1 but increased CgCDR1 expression 126-fold. Selectivity of the effect is compatible with the concept that milbemycin A4 oxime may interact directly with one or more drug-binding sites of the major azole transporters.

Original languageEnglish (US)
Pages (from-to)755-761
Number of pages7
JournalFEMS Yeast Research
Issue number5
StatePublished - Aug 2014
Externally publishedYes


  • Azole
  • Candida glabrata
  • Milbemycin
  • Resistance

ASJC Scopus subject areas

  • Microbiology
  • Applied Microbiology and Biotechnology


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