title: The thioredoxin system of Penicillium chrysogenum and its possible role in penicillin biosynthesis.
abstract: Penicillium chrysogenum is an important producer of penicillin antibiotics. A key step in their biosynthesis is the oxidative cyclization of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV) to isopenicillin N by the enzyme isopenicillin N synthase (IPNS). bis-ACV, the oxidized disulfide form of ACV is, however, not a substrate for IPNS. We report here the characterization of a broad-range disulfide reductase from P. chrysogenum that efficiently reduces bis-ACV to the thiol monomer. When coupled in vitro with IPNS, it converts bis-ACV to isopenicillin N and may therefore play a role in penicillin biosynthesis. The disulfide reductase consists of two protein components, a 72-kDa NADPH-dependent reductase, containing two identical subunits, and a 12-kDa general disulfide reductant. The latter reduces disulfide bonds in low-molecular-weight compounds and in proteins. The genes coding for the reductase system were cloned and sequenced. Both possess introns. A comparative analysis of their predicted amino acid sequences showed that the 12-kDa protein shares 26 to 60% sequence identity with thioredoxins and that the 36-kDa protein subunit shares 44 to 49% sequence identity with the two known bacterial thioredoxin reductases. In addition, the P. chrysogenum NADPH-dependent reductase is able to accept thioredoxin as a substrate. These results establish that the P. chrysogenum broad-range disulfide reductase is a member of the thioredoxin family of oxidoreductases. This is the first example of the cloning of a eucaryotic thioredoxin reductase gene.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Israel.
authors.forename: G
authors.initials: G
authors.lastname: Cohen
authors.forename: A
authors.initials: A
authors.lastname: Argaman
authors.forename: R
authors.initials: R
authors.lastname: Schreiber
authors.forename: M
authors.initials: M
authors.lastname: Mislovati
authors.forename: Y
authors.initials: Y
authors.lastname: Aharonowitz
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004220:Disulfides / Q000378:metabolism; D005800:Genes, Fungal / Q000235:genetics*; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism*; D010084:Oxidation-Reduction; D010406:Penicillins / Q000096:biosynthesis*; D010408:Penicillium chrysogenum / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013879:Thioredoxins / Q000235:genetics* / Q000378:metabolism
chemical_list: D004220:Disulfides; D009842:Oligopeptides; D010406:Penicillins; C011638:5-(2-aminoadipyl)cysteinylvaline; D013879:Thioredoxins; D009247:NADH, NADPH Oxidoreductases; C079399:delta-(alpha-aminoadipyl)cysteinylvalinedisulfide reductase; C006414:penicillin N