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Genes encoding multiple drug resistance-like proteins in Aspergillus fumigatus and Aspergillus flavus
M B Tobin1, R B Peery, P L Skatrud
1Department of Infectious Diseases, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA.
Abstract:
Polymerase chain reaction using degenerate primers was used to identify genes encoding proteins of the ATP-binding cassette superfamily in Aspergillus fumigatus and Aspergillus flavus. In A. fumigatus, two genes (AfuMDR1 and AfuMDR2) encoding proteins of the ATP-binding cassette superfamily were identified. One gene (AflMDR1) was isolated from A. flavus and is the apparent homologue to AfuMDR1. AfuMDR1 and AflMDR1 encode proteins of molecular weights 148,000 and 143,000, respectively, each containing 12 putative transmembrane regions and two ATP-binding sites. These proteins are arranged in two homologous halves, each half consisting of a hydrophobic region (encoding six putative transmembrane domains) and an ATP-binding site. The AfuMDR1 and AflMDR1-encoded proteins bear a high degree of similarity to the Schizosaccharomyces pombe leptomycin B resistance protein and to human MDR1. The second gene identified in A. fumigatus, AfuMDR2, encodes a protein of molecular weight 85,000, containing four putative transmembrane domains and an ATP binding domain. The encoded protein is similar to those encoded by MDL1 and MDL2, two MDR-like genes of Saccharomyces cerevisiae. Expression of AFUMDR1 in S. cerevisiae conferred increased resistance to the antifungal agent cilofungin (LY121019), an echinocandin B analog.
Insights
Researchers identified ATP-binding cassette superfamily genes in Aspergillus fumigatus and Aspergillus flavus. The AfuMDR1 gene from A. fumigatus conferred resistance to an antifungal agent when expressed in yeast, highlighting its potential role in drug resistance.
Area of Science:
- Mycology
- Molecular Biology
- Biochemistry
Background:
- ATP-binding cassette (ABC) superfamily proteins are crucial for various cellular transport processes.
- Understanding ABC transporters in pathogenic fungi like Aspergillus is vital for developing antifungal strategies.
Purpose of the Study:
- To identify and characterize genes encoding ABC superfamily proteins in Aspergillus fumigatus and Aspergillus flavus.
- To investigate the functional role of identified genes, particularly in relation to drug resistance.
Main Methods:
- Polymerase chain reaction (PCR) with degenerate primers was employed to identify target genes.
- Gene cloning and sequencing were performed to analyze the identified genes and their encoded proteins.
- Functional analysis involved expressing a gene in Saccharomyces cerevisiae to assess its effect on antifungal resistance.
Main Results:
- Two ABC superfamily genes, AfuMDR1 and AfuMDR2, were identified in A. fumigatus. A homologous gene, AflMDR1, was found in A. flavus.
- AfuMDR1 and AflMDR1 encode large proteins with multiple transmembrane domains and ATP-binding sites, showing similarity to known drug transporters.
- Expression of AfuMDR1 in S. cerevisiae resulted in increased resistance to the antifungal agent cilofungin.
Conclusions:
- The identified genes, AfuMDR1 and AflMDR1, represent potential drug efflux pumps in Aspergillus species.
- AfuMDR1 plays a role in conferring resistance to specific antifungal agents, suggesting its involvement in fungal drug resistance mechanisms.