bfr1+, a novel gene of Schizosaccharomyces pombe which confers brefeldin A resistance, is structurally related to the ATP-binding cassette superfamily.
We have isolated a Schizosaccharomyces pombe gene, bfr1+, which on a multicopy plasmid vector, pDB248', confers resistance to brefeldin A (BFA), an inhibitor of intracellular protein transport. This gene encodes a novel protein of 1,531 amino acids with an intramolecular duplicated structure, each half containing a single ATP-binding consensus sequence and a set of six transmembrane sequences. This structural characteristic of bfr1+ protein resembles that of mammalian P-glycoprotein, which, by exporting a variety of anticancer drugs, has been shown to be responsible for multidrug resistance in tumor cells. Consistent with this is that S. pombe cells harboring bfr1+ on pDB248' are resistant to actinomycin D, cerulenin, and cytochalasin B, as well as to BFA. The relative positions of the ATP-binding sequences and the clusters of transmembrane sequences within the bfr1+ protein are, however, transposed in comparison with those in P-glycoprotein; the bfr1+ protein has N-terminal ATP-binding sequence followed by transmembrane segments in each half of the molecule. The bfr1+ protein exhibited significant homology in primary and secondary structures with two recently identified multidrug resistance gene products of Saccharomyces cerevisiae, Snq2 and Sts1/Pdr5/Ydr1. The bfr1+ gene is not essential for cell growth or mating, but a delta bfr1 mutant exhibited hypersensitivity to BFA. We propose that the bfr1+ protein is another member of the ATP-binding cassette superfamily and serves as an efflux pump of various antibiotics.
Nagao
K
K
Department of Biotechnology, University of Tokyo, Japan.
Taguchi
Y
Y
Arioka
M
M
Kadokura
H
H
Takatsuki
A
A
Yoda
K
K
Yamasaki
M
M
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D020126:Brefeldin A; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000235:genetics; D018432:Drug Resistance, Multiple / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal / Q000235:genetics*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010641:Phenotype; D015183:Restriction Mapping; D012568:Schizosaccharomyces / Q000187:drug effects / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D018528:ATP-Binding Cassette Transporters; C092496:BFR1 protein, S pombe; D003517:Cyclopentanes; D005656:Fungal Proteins; D029702:Schizosaccharomyces pombe Proteins; D020126:Brefeldin A; D000255:Adenosine Triphosphate