Synthetases isopenicillin synthetase

Fig. 5. Biosynthesis of penicillins when ACV is aminoadipoly cysteinyl valine and IPNS is isopenicillin N synthase and CgH CH2COSCoA represents benzyl coenzyme A. ACV synthetase is thought to catalyze the first step of this reaction sequence.

The tripeptide LLD-ACV is then cydised to isopenicillin N by an oxidative reaction involving the removal of four protons. The enzyme that catalyses this reaction is isopenidllin N synthetase or synthase (IPNS). 

Abbreviations ACVS, 5-(L-a-aminoadipyl)-L-cysteinyl-D-valine Synthetase IPNS, isopenicillin N synthase IPNE, isopenicillin N epimerase DAOCS/ DACS, deacetoxycephalosporin C synthetase/deacetylcephalosporin C synthase DAC-AT, acetyl CoA deacetylcephalosporin C O-acety 1 transferase DTT, dithiothreitol. 

JE Baldwin, J Gagnon, H Ting. N-terminal amino acid sequence and some properties of isopenicillin-N synthetase from Cephalosporium acremonium. FEBS Lett 188 253-256, 1985. 

SM Samson, R Belagaje, DT Blankenship, JL Chapman, D Perry, PL Skatrud, RM VanFrank, EP Abraham, JE Baldwin, SW Queener, TD Ingolia. Isolation, sequence determination and expression in Escherichia coli of the isopenicillin N synthetase gene from Cephalosporium acremonium. Nature 318 191-194, 1985. 

FR Ramos, MJ Lopez-Nieto, JF Martin. Isopenicillin N synthetase of Penicillium chrysogenum, an enzyme that converts 5-(L-a-aminoadipyl)-L-cysteinyl-D-valine to isopenicillin N. Antimicrob Agents Chemother 27 380-387, 1985. 

SE Jensen, BK Leskiw, LC Vining, Y Aharonowitz, DWS Westlake, S Wolfe. Purification of isopenicillin N synthetase from Streptomyces clavuligerus. Can J Microbiol 32 953-958, 1986. 

JE Baldwin, SJ Killin, AJ Pratt, JD Sutherland, NJ Turner, MJC Crabbe, EP Abraham, AC Willis. Purification and characterization of cloned isopenicillin N synthetase. J Antibiot 40 652-659, 1987. 

S Kovacevic, MB Tobin, JR Miller. The (3-lactam biosynthesis genes for isopenicillin N epimerase and deacetoxycephalosporin C synthetase are expressed from a single transcript in Streptomyces clavuligerus. J Bacteriol 172 3952-3958, 1990. 

The biosynthesis of CPC is well known. The first step of CPC synthesis is the formation of the tripeptide S-(L-a-aminoadipyl)-L-cysteinlyl-D-valine (LLD-ACV) from L-a-aminoadipinic acid (AAA), L-cystein (CYS ) and D-valine (VAL) by the LLD-ACV synthetase (ACVS). LLD-ACV is converted with the enzyme isopenicillin AT-synthetase (cyclase) to isopenicillin N (IPN) and then with isopenicillin N-epimerase to penicillin N (PEN). The 6-ring is formed by deacetoxycephalosporin C-synthase (expandase). Deacetoxycephalosporin C (DAOC) is converted with deacetoxycephalosporin C-hydroxylase to decacetylcephalosporin C (DAC) and the latter with deacetylcephalosporin C-acyltransferase to CPC (Fig. 1). Except the amino acid and ACV, all others were monitored by on-line HPLC. 

Isopenicillin-N synthetase mononuclear iron 0 -lactam ring formation 3.2.2. 

Two groups have synthesized the thiazepinone (194) and its sulphoxide to test them as possible intermediates in the biosynthesis of isopenicillin N (195). However, neither (194) nor its sulphoxide behaved as substrates in a cell-free synthetase system from Cephalosporium acremonium ... 

Ktlck U, Walz M, Mohr G, Mracek M (1989). The 5 -sequence of the isopenicillin N-synthetase gene (pcbC) from Cephalosporium acremonium directs the expression of the prokaryotic hygromycin B phosphotransferase gene (hph) in Aspergillus niger. Appl. Microbiol. Biotechnol. 31 358-365. 

PEREZ-ESTEBAN, B., OREJAS, M., GOMEZ-PARDO, E., PESIALVA, M.A., Molecular characterization of a fungal secondary metabolism promoter Transcription of the Aspergillus nidulans isopenicillin N synthetase gene is modulated by upstream negative elements. Mol. Microbiol., 1993, 9, 881-895. 

Leskiw BK, Aharonowic Y. Mevarech M, Wolfe S. Vining LC, Westlake DWS, Jensen SE. Cloning and nucleotide sequence determination of the isopenicillin N synthetase gene from Streptomyces cknwligents. Gene 1988 62 187—196. 

Can LG, Skatrud PL, Scheet ME. Queener SW. Ingolia TD. Cloning and expression of the isopenicillin N synthetase gene from Peniciilium cfirysogenum. Gene 1986 48 257-266. 

Samson SM. Chapman JL, Belagaje R, Queener SW, Ingolia TD, Analysis of the role of cys-teine residues in isopenicillin N synthetase activity by site-directed mutagenesis. Proc Natl Acad Sci USA 1987 84 5705-5709. 

Ramsden M, McQuade BA, Saunders K, Turner MK, Harford S. Characterization of a loss-of-function in the isopenicillin N synthetase gene trf Acretnoiuum dnysqgenutn. Gene 1989 ... 

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