Terbinafine resistance mediated by salicylate 1-monooxygenase in Aspergillus nidulans.
Resistance to antifungal agents is a recurring and growing problem among patients with systemic fungal infections. UV-induced Aspergillus nidulans mutants resistant to terbinafine have been identified, and we report here the characterization of one such gene. A sib-selected, 6.6-kb genomic DNA fragment encodes a salicylate 1-monooxygenase (salA), and a fatty acid synthase subunit (fasC) confers terbinafine resistance upon transformation of a sensitive strain. Subfragments carrying salA but not fasC confer terbinafine resistance. salA is present as a single-copy gene on chromosome VI and encodes a protein of 473 amino acids that is homologous to salicylate 1-monooxygenase, a well-characterized naphthalene-degrading enzyme in bacteria. salA transcript accumulation analysis showed terbinafine-dependent induction in the wild type and the UV-induced mutant Terb7, as well as overexpression in a strain containing the salA subgenomic DNA fragment, probably due to the multicopy effect caused by the transformation event. Additional naphthalene degradation enzyme-coding genes are present in fungal genomes, suggesting that resistance could follow degradation of the naphthalene ring contained in terbinafine.
Graminha
Marcia A S
MA
Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, 14049-900 Ribeirão Preto, Sao Paulo, Brazil.
Rocha
Eleusa M F
EM
Prade
Rolf A
RA
Martinez-Rossi
Nilce M
NM
D000935:Antifungal Agents / Q000378:metabolism / Q000494:pharmacology*; D001233:Aspergillus nidulans / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D015152:Blotting, Northern; D015139:Blotting, Southern; D002874:Chromosome Mapping; D003470:Culture Media; D053938:DNA Fragmentation / Q000235:genetics; D017931:DNA Primers; D004271:DNA, Fungal / Q000235:genetics; D025141:Drug Resistance, Fungal; D064429:Fatty Acid Synthases / Q000378:metabolism; D015723:Gene Library; D005800:Genes, Fungal / Q000235:genetics; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000502:physiology*; D009281:Naphthalenes / Q000378:metabolism / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077291:Terbinafine; D014158:Transcription, Genetic; D014170:Transformation, Genetic
D000935:Antifungal Agents; D003470:Culture Media; D017931:DNA Primers; D004271:DNA, Fungal; D009281:Naphthalenes; D006899:Mixed Function Oxygenases; C022619:salicylate 1-monooxygenase; D064429:Fatty Acid Synthases; D000077291:Terbinafine