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Paradkar A, Jensen S, Mosher R. Comparative Genetics and Molecular Biology of ß-Lactam Biosynthesis. ACTA ACUST UNITED AC 2013. [DOI: 10.1201/b14856-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
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Malmberg LH, Hu WS. Kinetic analysis of cephalosporin biosynthesis in Streptomyces clavuligerus. Biotechnol Bioeng 2012; 38:941-7. [PMID: 18600850 DOI: 10.1002/bit.260380815] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A kinetic model describing the cephalosporin biosynthesis in Streptomyces clavuligerus was developed. Using previously reported kinetic data of biosynthetic enzymes, we examined the kinetics of cephalosporin production. The predicted time profile of the specific production rate during a batch culture parallels that of experimental observation. Sensitivity analysis reveals that delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV) synthetase is the rate-limiting enzyme. The effect of amplifying ACV synthetase on the specific production rate was analyzed theoretically. Increasing ACV synthetase enhances the production rate initially until ACV synthetase enhances the production rate initially until deacetocycephalosporin C hydroxylase becomes rate-limiting. Such kinetic analysis can provide a rational basis for modifying the biosynthetic machinery of cephalosporin through gene cloning.
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Affiliation(s)
- L H Malmberg
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Chapter 16. Enzymology of beta-lactam compounds with cephem structure produced by actinomycete. Methods Enzymol 2009; 458:401-29. [PMID: 19374992 DOI: 10.1016/s0076-6879(09)04816-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Cephamycins are beta-lactam antibiotics with a cephem structure produced by actinomycetes. They are synthesized by a pathway similar to that of cephalosporin C in filamentous fungi but the actinomycetes pathway contains additional enzymes for the formation of the alpha-aminoadipic acid (AAA) precursor and for the final steps specific to cephemycins. Most of the biochemical and genetic studies on cephemycins have been made on cephemycin C biosynthesis in the producer strains Streptomyces clavuligerus ATCC27064 and Amycolatopsis lactamdurans NRRL3802. Genes encoding cephamycin C biosynthetic enzymes are clustered in both actinomycetes. Ten enzymatic steps are involved in the formation of cephamycin C. The precursor alpha-AAA is formed by the sequential action of lysine-6-aminotransferase and piperideine-6-carboxylate dehydrogenase. Steps common to cephalosporin C biosynthesis include the formation of the tripeptide L-delta-alpha-aminoadipyl-L-cysteinyl-D-valine (ACV) by ACV synthetase, the cyclization of ACV to form isopenicillin N (IPN) by IPN synthase, the epimerization of IPN to penicillin N by isopenicillin N epimerase, the ring expansion of penicillin N to a six member cephem ring by deacetoxycephalosporin C synthase (DAOCS) and the hydroxylation at C-3' by deacetylcephalosporin C hydroxylase. However, in actinomycetes, the epimerization step is different from that in cephalosporin-producing fungi, and the expansion of the ring and its hydroxylation are performed by separate enzymes. Specific steps in cephamycin biosynthesis include the carbamoylation at C-3' by cephem carbamoyl transferase and the introduction of a methoxyl group at C-7 by the joint action of a C-7 cephem-hydroxylase and a methyltransferase. All the enzymes of the pathway have been purified almost to homogeneity and the DAOC synthase and 7-hydroxycephem-methyltransferase (CmcI) of S. clavuligerus have been crystallized giving insights into the mode of action of these enzymes. The cefE gene of S. clavuligerus, encoding DAOCS, has been extensively used to expand the penicillin ring in filamentous fungi in vivo using DNA recombinant technology.
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Hamed RB, Batchelar ET, Mecinović J, Claridge TDW, Schofield CJ. Evidence that Thienamycin Biosynthesis Proceeds via C-5 Epimerization: ThnE Catalyzes the Formation of (2S,5S)-trans-Carboxymethylproline. Chembiochem 2009; 10:246-50. [DOI: 10.1002/cbic.200800652] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Felnagle EA, Jackson EE, Chan YA, Podevels AM, Berti AD, McMahon MD, Thomas MG. Nonribosomal peptide synthetases involved in the production of medically relevant natural products. Mol Pharm 2008; 5:191-211. [PMID: 18217713 PMCID: PMC3131160 DOI: 10.1021/mp700137g] [Citation(s) in RCA: 203] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Natural products biosynthesized wholly or in part by nonribosomal peptide synthetases (NRPSs) are some of the most important drugs currently used clinically for the treatment of a variety of diseases. Since the initial research into NRPSs in the early 1960s, we have gained considerable insights into the mechanism by which these enzymes assemble these natural products. This review will present a brief history of how the basic mechanistic steps of NRPSs were initially deciphered and how this information has led us to understand how nature modified these systems to generate the enormous structural diversity seen in nonribosomal peptides. This review will also briefly discuss how drug development and discovery are being influenced by what we have learned from nature about nonribosomal peptide biosynthesis.
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Affiliation(s)
| | | | | | | | | | | | - Michael G. Thomas
- Department of Bacteriology, University of Wisconsin-Madison, Madison WI 53706
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Kelly WL, Townsend CA. Mutational analysis and characterization of nocardicin C-9' epimerase. J Biol Chem 2004; 279:38220-7. [PMID: 15252031 DOI: 10.1074/jbc.m405450200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biosynthetic gene cluster for the nocardicin A producer Nocardia uniformis subsp. tsuyamanensis ATCC 21806 was recently identified. Nocardicin A is the most potent of a series of monocyclic beta-lactam antibiotics produced by this organism. Its activity has been attributed to a syn-configured oxime moiety and a d-homoseryl side chain attached through an unusual ether linkage to the core nocardicin framework. Notably present in the nocardicin biosynthetic gene cluster is nocJ, encoding a protein with sequence similarity to the pyridoxal 5'-phosphate (PLP)-dependent 1-aminocyclopropane-1-carboxylic acid deaminases. Insertional mutagenesis of nocJ abolished nocardicin A production, while the l-homoseryl isomer, isonocardicin A, was still observed. Expression of the disrupted nocJ gene in trans was sufficient to restore production of nocardicin A in the disruption mutant. Heterologous expression, purification, and in vitro characterization of NocJ by UV spectroscopy, cofactor reduction, chiral HPLC analysis of the products and their exchange behavior in deuterium oxide led to confirmation of its role as the PLP-dependent nocardicin C-9' epimerase responsible for interconversion of the nocardicin homoseryl side chain in both nocardicin A with isonocardicin A, and nocardicin C with isonocardicin C. NocJ is the first member of a new class of beta-lactam aminoacyl side chain epimerases, the first two classes being the evolutionarily distinct prokaryotic PLP-dependent isopenicillin N epimerase and the fungal isopenicillin N epimerase two protein system.
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Affiliation(s)
- Wendy L Kelly
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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Abstract
Metabolic engineering has become a rational alternative to classical strain improvement in optimisation of beta-lactam production. In metabolic engineering directed genetic modification are introduced to improve the cellular properties of the production strains. This has resulted in substantial increases in the existing beta-lactam production processes. Furthermore, pathway extension, by heterologous expression of novel genes in well-characterised strains, has led to introduction of new fermentation processes that replace environmentally damaging chemical methods. This minireview discusses the recent developments in metabolic engineering and the applications of this approach for improving beta-lactam production.
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Affiliation(s)
- Jette Thykaer
- Center for Process Biotechnology, BioCentrum, Technical University of Denmark, Building 223, DK-2800, Lyngby, Denmark
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Ullan RV, Casqueiro J, Banuelos O, Fernandez FJ, Gutierrez S, Martin JF. A novel epimerization system in fungal secondary metabolism involved in the conversion of isopenicillin N into penicillin N in Acremonium chrysogenum. J Biol Chem 2002; 277:46216-25. [PMID: 12228250 DOI: 10.1074/jbc.m207482200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epimerization step that converts isopenicillin N into penicillin N during cephalosporin biosynthesis has remained uncharacterized despite its industrial relevance. A transcriptional analysis of a 9-kb region located downstream of the pcbC gene revealed the presence of two transcripts that correspond to the genes named cefD1 and cefD2 encoding proteins with high similarity to long chain acyl-CoA synthetases and acyl-CoA racemases from Mus musculus, Homo sapiens, and Rattus norvegicus. Both genes are expressed in opposite orientations from a bidirectional promoter region. Targeted inactivation of cefD1 and cefD2 was achieved by the two-marker gene replacement procedure. Disrupted strains lacked isopenicillin N epimerase activity, were blocked in cephalosporin C production, and accumulated isopenicillin N. Complementation in trans of the disrupted nonproducer mutant with both genes restored epimerase activity and cephalosporin biosynthesis. However, when cefD1 or cefD2 were introduced separately into the double-disrupted mutant, no epimerase activity was detected, indicating that the concerted action of both proteins encoded by cefD1 and cefD2 is required for epimerization of isopenicillin N into penicillin N. This epimerization system occurs in eukaryotic cells and is entirely different from the known epimerization systems involved in the biosynthesis of bacterial beta-lactam antibiotics.
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Affiliation(s)
- Ricardo V Ullan
- Area de Microbiologia, Facultad de Ciencias Biológicas y Ambientales, Universidad de León, 24071 León, Spain
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Abstract
The genes pcbAB, pcbC and penDE encoding enzymes involved in the biosynthesis of penicillin have been cloned from Penicillium chrysogenum and Aspergillus nidulans. They are clustered in chromosome I (10.4 Mb) of P. chrysogenum, but they are located in chromosome II of Penicillium notatum (9.6 Mb) and in chromosome VI (3.0 Mb) of A. nidulans. Expression studies have shown that each gene is expressed as a single transcript from separate promoters. Enzyme regulation studies and gene expression analysis have provided useful information to understand the control of gene expression leading to overexpression of the genes involved in penicillin biosynthesis. Cephalosporin genes have been studied in Cephalosporium acremonium and also in cephalosporin-producing bacteria. In C. acremonium the genes involved in cephalosporin biosynthesis are separated in at least two clusters. Cluster I (pcbAB-pcbC) encodes the first two enzymes of the cephalosporin pathway which are very similar to those involved in penicillin biosynthesis. Cluster II (cefEF-cefG), encodes the last three enzymatic activities of the cephalosporin pathway. It is unknown, at this time, if the cefD gene encoding isopenicillin epimerase is linked to any of the two clusters. In cephamycin producing bacteria the genes encoding the entire biosynthetic pathway are located in a single cluster extending for about 30 kb in Nocardia lactamdurans, and in Streptomyces clavuligerus. The cephamycin clusters of N. lactamdurans and S. clavuligerus include a gene lat which encodes lysine-6-aminotransferase an enzyme involved in formation of the precursor alpha-aminoadipic acid. The N. lactamdurans cephamycin cluster includes, in addition, a beta-lactamase (bla) gene, a penicillin binding protein (pbp), and a transmembrane protein gene (cmcT) that is probably involved in secretion of the cephamycin. Little is known however about the mechanism of control of gene expression in the different beta-lactam producers. The availability of most of the structural genes provides a good basis for further studies on gene expression. This knowledge should lead in the next decade to a rational design of strain improvement procedures. The origin and evolution of beta-lactam genes is intriguing since their nucleotide sequences are extremely conserved despite their restricted distribution in the microbial world.
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Affiliation(s)
- J F Martín
- Department of Ecology, Genetics and Microbiology, Faculty of Biology, University of León, Spain
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Affiliation(s)
- S E Jensen
- Department of Microbiology, University of Alberta Edmonton, Canada
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Pascarella S, Schirch V, Bossa F. Similarity between serine hydroxymethyltransferase and other pyridoxal phosphate-dependent enzymes. FEBS Lett 1993; 331:145-9. [PMID: 8405393 DOI: 10.1016/0014-5793(93)80314-k] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A structural homology of the pyridoxal-5'-phosphate (PLP)-dependent enzyme serine hydroxymethyltransferase (SHMT) with aspartate aminotransferase (AAT) is proposed. Although the two sequences are very dissimilar, a reasonable alignment was obtained using the profile analysis method. Sequences of AAT and dialkylglycine decarboxylase (DGD), for which crystal structure data are available, have been aligned on the basis of their structure superposition. A profile was then calculated and SHMT sequence aligned to it. Three of the four residues conserved in all aminotransferases (including the PLP-binding lysine) are matched. A profile search with DGD-AAT-SHMT profile is more selective and sensitive than individual sequence profiles for PLP-dependent enzyme detection. Potential homologies with the eryC1 gene product involved in erythromycin biosynthesis and with amino acid decarboxylases were observed. Homology with AAT will be used as a guideline for planning site-directed mutagenesis experiments on SHMT.
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Affiliation(s)
- S Pascarella
- Dipartimento di Scienze Biochimiche A Rossi Fanelli, Università La Sapienza, Roma, Italy
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Ouzounis C, Sander C. Homology of the NifS family of proteins to a new class of pyridoxal phosphate-dependent enzymes. FEBS Lett 1993; 322:159-64. [PMID: 8482384 DOI: 10.1016/0014-5793(93)81559-i] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Iterative profile sequence analysis reveals a remote homology of peroxisomal serine-pyruvate aminotransferases from mammals to the small subunit of soluble hydrogenases from cyanobacteria, an isopenicillin N epimerase, the NifS gene products from bacteria and yeast, and the phosphoserine aminotransferase family. All members of this new class whose function is known are pyridoxal phosphate-dependent enzymes, yet they have distinct catalytic activities. Upon alignment, a lysine around position 200 remains invariant and is predicted to be the pyridoxal phosphate-binding residue. Based on the detected homology, it is predicted that NifS has also a pyridoxal phosphate-dependent serine (or related) aminotransferase function associated with nitrogen economy and/or protection during nitrogen fixation.
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Affiliation(s)
- C Ouzounis
- Protein Design Group, European Molecular Biology Laboratory, Heidelberg, Germany
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Coque JJ, Martín JF, Liras P. Characterization and expression in Streptomyces lividans of cefD and cefE genes from Nocardia lactamdurans: the organization of the cephamycin gene cluster differs from that in Streptomyces clavuligerus. MOLECULAR & GENERAL GENETICS : MGG 1993; 236:453-8. [PMID: 8437592 DOI: 10.1007/bf00277148] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The cefD and cefE genes of Nocardia lactamdurans, which encode isopenicillin N epimerase and deacetoxycephalosporin C synthase respectively, have been located 0.63 kb upstream from the lysine-6-amino-transferase (lat) gene. cefD contains an open reading frame (ORF) of 1197 nucleotides (nt) encoding a protein of 398 amino acids with a M(r) of 43,622. The deduced amino acid sequence exhibits 62.2% identity to the cefD gene product of Streptomyces clavuligerus. The sequence SXHKXL in isopenicillin N epimerase resembles the consensus sequence for pyridoxal phosphate binding found in several amino acid decarboxylases from Enterobacteria. cefE contains an ORF of 945 nt encoding a protein of 314 amino acids with a M(r) of 34,532, which is similar to the deacetoxycephalosporin C synthase of S. clavuligerus. Expression of both genes, cefD and cefE, in S. lividans transformants, results in deacetoxycephalosporin C synthase and isopenicillin N epimerase activities that are 10-12 times higher than those in N. lactamdurans. The cefD and cefE genes of N. lactamdurans are closely linked but the overall organization of the cephamycin gene cluster differs in N. lactamdurans and S. clavuligerus.
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Affiliation(s)
- J J Coque
- Faculty of Biology, Dpt. of Ecology, Genetics and Microbiology, University of León, Spain
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YEH WK, GHAG SK, QUEENER SW. Enzymes for Epimerization of Isopenicillin N, Ring Expansion of Penicillin N, and 3'-Hydroxylation of Deacetoxycephalosporin C. Ann N Y Acad Sci 1992. [DOI: 10.1111/j.1749-6632.1992.tb35649.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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YEH WK, GHAG SK, QUEENER SW. Enzymes for Epimerization of Isopenicillin N, Ring Expansion of Penicillin N, and 3'-Hydroxylation of Deacetoxycephalosporin C. Ann N Y Acad Sci 1992. [DOI: 10.1111/j.1749-6632.1992.tb32705.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Affiliation(s)
- L H Malmberg
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis 55455
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Gerlt JA, Kenyon GL, Kozarich JW, Neidhart DJ, Petsko GA, Powers VM. Mandelate racemase and class-related enzymes. Curr Opin Struct Biol 1992. [DOI: 10.1016/0959-440x(92)90209-p] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
ACV synthetase (ACVS) is the first enzyme and plays a key role in the biosynthesis of all natural penicillins and cephalosporins. The enzyme is extremely unstable and little had been known about it until recently. This article summarizes the progress in research on this enzyme, including the establishment of a cell-free assay system, stabilization, purification, characterization, and gene cloning. A possible reaction sequence for ACVS catalysis is suggested.
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Affiliation(s)
- J Zhang
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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Rambosek JA. Molecular biology and biochemistry of the beta-lactam antibiotics. BIOTECHNOLOGY (READING, MASS.) 1992; 21:221-39. [PMID: 1576480 DOI: 10.1016/b978-0-7506-9115-4.50015-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Baker BJ, Dotzlaf JE, Yeh WK. Deacetoxycephalosporin C hydroxylase of Streptomyces clavuligerus. Purification, characterization, bifunctionality, and evolutionary implication. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)67759-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Gutiérrez S, Díez B, Alvarez E, Barredo JL, Martín JF. Expression of the penDE gene of Penicillium chrysogenum encoding isopenicillin N acyltransferase in Cephalosporium acremonium: production of benzylpenicillin by the transformants. MOLECULAR & GENERAL GENETICS : MGG 1991; 225:56-64. [PMID: 1900348 DOI: 10.1007/bf00282642] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
No DNA sequence homologous to the penDE gene of Penicillium chrysogenum was found in the genome of three different strains of Cephalosporium acremonium. The pcbC-penDE gene cluster of P. chrysogenum complemented the isopenicillin N synthase deficiency of C. acremonium mutant N2 and resulted in the production of penicillin, in addition to cephalosporin, in cultures supplemented with phenylacetic acid. The penicillin formed was identified as benzylpenicillin by HPLC and NMR studies. The penDE gene of P. chrysogenum is expressed in C. acremonium forming a transcript of 1.15 kb. The transcript is processed and translated in C. acremonium resulting in the formation of acyl CoA: isopenicillin N acyl transferase. When the penDE gene was introduced into a cephalosporin producing strain, the total titre of beta-lactam antibiotics comprised distinct proportions of penicillin and cephalosporin in different transformants. Analysis of the hybridization patterns of the DNA of C. acremonium transformed with the pcbC or penDE genes indicated that integration occurs by non-homologous recombination.
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Affiliation(s)
- S Gutiérrez
- Department of Ecology, Faculty of Biology, University of León, Spain
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Yeh WK, Queener SW. Potential industrial use of cephalosporin biosynthetic enzymes and genes. An overview. Ann N Y Acad Sci 1990; 613:128-41. [PMID: 2075972 DOI: 10.1111/j.1749-6632.1990.tb18154.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- W K Yeh
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285
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Kovacevic S, Tobin MB, Miller JR. The beta-lactam biosynthesis genes for isopenicillin N epimerase and deacetoxycephalosporin C synthetase are expressed from a single transcript in Streptomyces clavuligerus. J Bacteriol 1990; 172:3952-8. [PMID: 1694525 PMCID: PMC213379 DOI: 10.1128/jb.172.7.3952-3958.1990] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Isopenicillin N isomerase (epimerase) has been purified from Streptomyces clavuligerus, and the amino acid sequence of the N-terminus has been determined. By using single oligonucleotide probes based on high GC codon bias ("guessmers"), the translation start codons were determined for two successive genes in the beta-lactam-biosynthetic pathway and mapped within a 3.6-kilobase-pair KpnI restriction fragment. The epimerase gene (cefD) was located immediately upstream of the deacetoxycephalosporin C synthetase (expandase) gene (cefE) that was characterized previously. cefD was sequenced and expressed in Escherichia coli; the resulting cell extracts contained epimerase activity. Western immunoblots demonstrated that a protein comigrated with purified S. clavuligerus epimerase at 44 kilodaltons. cefD and cefE were separated by an 81-base-pair segment. The DNA sequence upstream of the epimerase gene had a high AT content, suggestive of a promoter region. Primer extension analysis of S. clavuligerus mRNA showed that the start of transcription occurred approximately 130 base pairs upstream of the epimerase translation start site; Northern (RNA blot) analysis revealed a hybridization signal large enough to code for both epimerase and expandase, and nuclease S1 protection assays showed that a single message may code for epimerase, expandase, and another unknown protein. When cefD and cefE were placed in an expression vector, concomitant synthesis of both epimerase and expandase occurred in E. coli.
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Affiliation(s)
- S Kovacevic
- Department of Molecular Genetics Research, Lilly Corporate Center, Indianapolis, Indiana 16285
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Queener SW. Molecular biology of penicillin and cephalosporin biosynthesis. Antimicrob Agents Chemother 1990; 34:943-8. [PMID: 2203307 PMCID: PMC171734 DOI: 10.1128/aac.34.6.943] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- S W Queener
- Cell Culture Research & Development, Eli Lilly & Company, Indianapolis, Indiana 46285
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