title: Candida albicans estrogen-binding protein gene encodes an oxidoreductase that is inhibited by estradiol.
abstract: Candida albicans, the most common fungal pathogen of humans, possesses an estrogen-binding protein (EBP) that binds mammalian estrogens with high affinity. We report here the cloning and complete nucleotide sequence of a gene encoding a C. albicans EBP. Amino acid sequences obtained from cyanogen bromide fragments of purified EBP were used to design oligonucleotide primers for PCR. An 800-bp product was amplified and used to screen a C. albicans genomic library. A clone was isolated containing an insert with an open reading frame of 1221 nt capable of encoding a protein with 407 amino acids and having a calculated molecular mass of 46,073 Da, the estimated size of EBP. The cloned gene, expressed in Escherichia coli as a lacZ fusion protein, demonstrated high-affinity binding for estradiol and a competition profile comparable to C. albicans wild-type EBP. Northern blots of C. albicans RNA revealed a single transcript of approximately 1600 nt, whereas Southern blots identified three hybridizing fragments. Computer searches of data bases showed that EBP shares a 46% amino acid identity with the old yellow enzyme, an oxidoreductase from Saccharomyces cerevisiae, but was unrelated to the human estrogen receptor as previously speculated. In addition, a 51-amino acid region of EBP is highly conserved among a group of flavoproteins including old yellow enzyme. Expressed EBP was shown to exhibit oxidoreductase activity that could be inhibited by 17 beta-estradiol in vitro. In conclusion, the EBP from C. albicans has no evident homology to the mammalian steroid receptor superfamily but appears to be a member of a recently identified family of flavoproteins.
authors.affiliation: Department of Medicine, Stanford University School of Medicine, CA 94305.
authors.forename: N D
authors.initials: ND
authors.lastname: Madani
authors.forename: P J
authors.initials: PJ
authors.lastname: Malloy
authors.forename: P
authors.initials: P
authors.lastname: Rodriguez-Pombo
authors.forename: A V
authors.initials: AV
authors.lastname: Krishnan
authors.forename: D
authors.initials: D
authors.lastname: Feldman
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002176:Candida albicans / Q000235:genetics* / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism*; D005800:Genes, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D009252:NADPH Dehydrogenase / Q000235:genetics; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000235:genetics*; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D002352:Carrier Proteins; D004271:DNA, Fungal; D004967:Estrogens; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; C010140:estrophilin; D004958:Estradiol; D010088:Oxidoreductases; D009252:NADPH Dehydrogenase