The RTA3 Gene, Encoding a Putative Lipid Translocase, Influences the Susceptibility of Candida albicans to Fluconazole

• Published in: Antimicrobial agents and chemotherapy Vol. 60; no. 10; pp. 6060 - 6066
• Main Authors: Whaley, Sarah G, Tsao, Sarah, Weber, Sandra, Zhang, Qing, Barker, Katherine S, Raymond, Martine, Rogers, P David
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.10.2016
• Subjects: Antifungal Agents; Antifungal Agents - pharmacology; Candida albicans; Candida albicans - drug effects; Candida albicans - genetics; Candida albicans - growth & development; Candida albicans - metabolism; Drug Resistance, Fungal; Drug Resistance, Fungal - genetics; Fluconazole; Fluconazole - pharmacology; Fungal Proteins; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Expression Regulation, Fungal; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Mechanisms of Resistance; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Mutation; Phospholipid Transfer Proteins; Phospholipid Transfer Proteins - genetics; Phospholipid Transfer Proteins - metabolism; Protein Isoforms - genetics; Protein Isoforms - metabolism; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Transformation, Bacterial
• ISSN: 0066-4804; 1098-6596
• DOI: 10.1128/AAC.00732-16

The RTA3 gene, coding for a member of the Rta1p-like lipid-translocating exporter family, is coordinately upregulated with the ATP-binding cassette transporter genes CDR1 and CDR2 in azole-resistant clinical isolates of Candida albicans that carry activating mutations in the transcription factor Tac1p. We show here that deleting RTA3 in an azole-resistant clinical isolate carrying a Tac1p-activating mutation lowered fluconazole resistance by 2-fold, while overexpressing RTA3 in an azole-susceptible clinical isolate resulted in enhanced fluconazole tolerance associated with trailing growth in a liquid microtiter plate assay. We also demonstrate that an Rta3p-green fluorescent protein (GFP) fusion protein localizes predominantly to the plasma membrane, consistent with a putative function for Rta3p as a lipid translocase.