The pfr1 gene from the human pathogenic fungus Paracoccidioides brasiliensis encodes a half-ABC transporter that is transcribed in response to treatment with fluconazole.
We have isolated a gene that encodes a half-ABC-transporter, designated Pfr1, from the dimorphic human pathogenic fungus Paracoccidioides brasiliensis, which has high identity with members of the ABC-superfamily involved in multidrug resistance. The pfr1 gene is predicted to encode a 827 amino acid protein that, in common with mammalian Mdr1, has a TM-NBD topology. The transcription of the pfr1 gene is induced by the triazole drug fluconazole but not by amphotericin B, suggesting a role in transport-mediated azole resistance. However, Pfr1 has greatest identity to the mitochondrial ABC transporters Mdl1 and Mdl2 from Saccharomyces cerevisiae and mammalian ABC-me, with identities of 47.2%, 40.6% and 39.5%, respectively, over the length of these proteins. Furthermore, the N-terminus of Pfr1 is rich in positively charged residues, a feature of mitochondrial targeting sequences. Considering these features, it seems likely that Pfr1 is a mitochondrial protein. Previous studies have revealed that the acquisition of azole resistance in S. cerevisiae is linked to mitochondrial loss and, conversely, that mitochondrial dysfunction can lead to the upregulation of PDR transporters mediated by the transcription factor Pdr3. Our studies suggest that a mitochondrial ABC transporter is induced as part of the cellular response to drug treatment. The promoter region of pfr1 contains a PDRE-like consensus sequence to which Pdr3 binds, which may be the element responsible for the upregulation of Pfr1 in response to fluconazole. The nucleotide binding domain of Pfr1 was expressed and purified from Escherichia coli and shown to retain ATPase activity, consistent with Pfr1 functioning as a homodimeric transport ATPase.
Gray
Christopher H
CH
Centre for Infectious Diseases, Wolfson Research Institute, University of Durham, Queen's Campus, Stockton-on-Tees TS17 6BH, UK.
Ines Borges-Walmsley
M
M
Evans
Gareth J
GJ
Walmsley
Adrian R
AR
D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000235:genetics*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000494:pharmacology*; D001483:Base Sequence; D003001:Cloning, Molecular; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology*; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics*; D005800:Genes, Fungal / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D006801:Humans; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010228:Paracoccidioides / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D012331:RNA, Fungal / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015854:Up-Regulation / Q000187:drug effects
D018528:ATP-Binding Cassette Transporters; D000935:Antifungal Agents; D005656:Fungal Proteins; D012331:RNA, Fungal; D015725:Fluconazole; D000251:Adenosine Triphosphatases