Loss of the yeast transporter Agp2 upregulates the pleiotropic drug-resistant pump Pdr5 and confers resistance to the protein synthesis inhibitor cycloheximide

• Published in: PloS one Vol. 19; no. 5; p. e0303747
• Main Authors: Manzoor, Yusra, Aouida, Mustapha, Ramadoss, Ramya, Moovarkumudalvan, Balasubramanian, Ahmed, Nisar, Sulaiman, Abdallah Alhaj, Mohanty, Ashima, Ali, Reem, Mifsud, Borbala, Ramotar, Dindial
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22.05.2024; Public Library of Science (PLoS)
• Subjects: Amino acids; Analysis; Antimitotic agents; Antineoplastic agents; Antineoplastic drugs; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Biology and Life Sciences; Bleomycin; Cancer; Carnitine; Cycloheximide; Cycloheximide - pharmacology; Degradation; Derepression; Drug resistance; Drug Resistance, Fungal - drug effects; Drug Resistance, Fungal - genetics; Efflux; Ethylenediaminetetraacetic acid; Gene expression; Gene Expression Regulation, Fungal - drug effects; Genes; Genomes; Inhibitors; Levocarnitine; Mass spectrometry; Mass spectroscopy; Membranes; Mutants; Oxidation; Plasma; Polyamines; Protein biosynthesis; Protein synthesis; Protein Synthesis Inhibitors - pharmacology; Proteins; Research and Analysis Methods; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Sensors; Up-Regulation - drug effects; Yeast; Yeasts
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0303747

The transmembrane protein Agp2, initially shown as a transporter of L-carnitine, mediates the high-affinity transport of polyamines and the anticancer drug bleomycin-A5. Cells lacking Agp2 are hyper-resistant to polyamine and bleomycin-A5. In these earlier studies, we showed that the protein synthesis inhibitor cycloheximide blocked the uptake of bleomycin-A5 into the cells suggesting that the drug uptake system may require de novo synthesis. However, our recent findings demonstrated that cycloheximide, instead, induced rapid degradation of Agp2, and in the absence of Agp2 cells are resistant to cycloheximide. These observations raised the possibility that the degradation of Agp2 may allow the cell to alter its drug resistance network to combat the toxic effects of cycloheximide. In this study, we show that membrane extracts from agp2Δ mutants accentuated several proteins that were differentially expressed in comparison to the parent. Mass spectrometry analysis of the membrane extracts uncovered the pleiotropic drug efflux pump, Pdr5, involved in the efflux of cycloheximide, as a key protein upregulated in the agp2Δ mutant. Moreover, a global gene expression analysis revealed that 322 genes were differentially affected in the agp2Δ mutant versus the parent, including the prominent PDR5 gene and genes required for mitochondrial function. We further show that Agp2 is associated with the upstream region of the PDR5 gene, leading to the hypothesis that cycloheximide resistance displayed by the agp2Δ mutant is due to the derepression of the PDR5 gene.