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Song S, Jiang Y, Chen R, Su W, Liang W, Yang D, Li J, Zhang W, Gao S, Yuan B, Qu G, Sun Z. Whole-cell Biotransformation of Penicillin G by a Three-enzyme Co-expression System with Engineered Deacetoxycephalosporin C Synthase. Chembiochem 2022; 23:e202200179. [PMID: 35384232 DOI: 10.1002/cbic.202200179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/06/2022] [Indexed: 11/10/2022]
Abstract
Deacetoxycephalosporin C synthase (DAOCS) catalyzes the tranformation of penicillin G to phenylacetyl-7-aminodeacetoxycephalosporanic acid (G-7-ADCA) in dependence on 2-oxoglutarate (2OG). However, the low activity of DAOCS and the expense of 2OG restricted the practical application in the production of G-7-ADCA. Herein, a rational design campaign was performed on a DAOCS from Streptomyces clavuligerus (scDAOCS) in the quest to construct novel expandases. The resulting mutants showed 25~58% increase in activity compared to the template. The dominant DAOCS variants were then embeded into a three-enzyme co-expression system, consisting of a catalase and a L-glutamic oxidase for the generation of 2OG, to convert penicillin G into G-7-ADCA in E. coli . The engineered whole-cell enzyme cascade was applied on an up scaled reaction, exhibiting a yield of G-7-ADCA up to 39.21 mM (14.6 g·L -1 ) with a conversion of 78.42 mol%. This work highlights the potential of the integrated whole-cell system that may inspire further research on green and efficient production of 7-ADCA.
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Affiliation(s)
- Shiyi Song
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Yingying Jiang
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Ruidong Chen
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Wencheng Su
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, 32 West 7th Avenue, Tianjin Airport Economic Area, 300308, Tianjin, CHINA
| | - Weinan Liang
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Dameng Yang
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, 32 West 7th Avenue, Tianjin Airport Economic Area, 300308, CHINA
| | - Jincheng Li
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Wuyuan Zhang
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Shushan Gao
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Bo Yuan
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Ge Qu
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, TIB, CHINA
| | - Zhoutong Sun
- Tianjin Institute of Industrial Biotechnology Chinese Academy of Sciences, National Enyzme Engineering Lab, 32 West 7th Avenue, Tianjin Airport Economic Area, 300308, Tianjin, CHINA
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2
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Wojdyla Z, Borowski T. Properties of the Reactants and Their Interactions within and with the Enzyme Binding Cavity Determine Reaction Selectivities. The Case of Fe(II)/2-Oxoglutarate Dependent Enzymes. Chemistry 2022; 28:e202104106. [PMID: 34986268 DOI: 10.1002/chem.202104106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Indexed: 12/12/2022]
Abstract
Fe(II)/2-oxoglutarate dependent dioxygenases (ODDs) share a double stranded beta helix (DSBH) fold and utilise a common reactive intermediate, ferryl species, to catalyse oxidative transformations of substrates. Despite the structural similarities, ODDs accept a variety of substrates and facilitate a wide range of reactions, that is hydroxylations, desaturations, (oxa)cyclisations and ring rearrangements. In this review we present and discuss the factors contributing to the observed (regio)selectivities of ODDs. They span from inherent properties of the reactants, that is, substrate molecule and iron cofactor, to the interactions between the substrate and the enzyme's binding cavity; the latter can counterbalance the effect of the former. Based on results of both experimental and computational studies dedicated to ODDs, we also line out the properties of the reactants which promote reaction outcomes other than the "default" hydroxylation. It turns out that the reaction selectivity depends on a delicate balance of interactions between the components of the investigated system.
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Affiliation(s)
- Zuzanna Wojdyla
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Niezapominajek 8, 30239 Krakow, Poland
| | - Tomasz Borowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Niezapominajek 8, 30239 Krakow, Poland
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3
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Biosynthesis of β-lactam nuclei in yeast. Metab Eng 2022; 72:56-65. [PMID: 35245651 DOI: 10.1016/j.ymben.2022.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/21/2022] [Accepted: 02/26/2022] [Indexed: 11/24/2022]
Abstract
We have engineered brewer's yeast as a general platform for de novo synthesis of diverse β-lactam nuclei starting from simple sugars, thereby enabling ready access to a number of structurally different antibiotics of significant pharmaceutical importance. The biosynthesis of β-lactam nuclei has received much attention in recent years, while rational engineering of non-native antibiotics-producing microbes to produce β-lactam nuclei remains challenging. Benefited by the integration of heterologous biosynthetic pathways and rationally designed enzymes that catalyze hydrolysis and ring expansion reactions, we succeeded in constructing synthetic yeast cell factories which produce antibiotic cephalosporin C (CPC, 170.1 ± 4.9 μg/g DCW) and the downstream β-lactam nuclei, including 6-amino penicillanic acid (6-APA, 5.3 ± 0.2 mg/g DCW), 7-amino cephalosporanic acid (7-ACA, 6.2 ± 1.1 μg/g DCW) as well as 7-amino desacetoxy cephalosporanic acid (7-ADCA, 1.7 ± 0.1 mg/g DCW). This work established a Saccharomyces cerevisiae platform capable of synthesizing multiple β-lactam nuclei by combining natural and artificial enzymes, which serves as a metabolic tool to produce valuable β-lactam intermediates and new antibiotics.
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Niu X, Zhang J, Xue X, Wang D, Wang L, Gao Q. Deacetoxycephalosporin C synthase (expandase): Research progress and application potential. Synth Syst Biotechnol 2021; 6:396-401. [PMID: 34901478 PMCID: PMC8626558 DOI: 10.1016/j.synbio.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 12/02/2022] Open
Abstract
Cephalosporins play an indispensable role against bacterial infections. Deacetyloxycephalosporin C synthase (DAOCS), also called expandase, is a key enzyme in cephalosporin biosynthesis that epoxides penicillin to form the hexavalent thiazide ring of cephalosporin. DAOCS in fungus Acremonium chrysogenum was identified as a bifunctional enzyme with both ring expansion and hydroxylation, whereas two separate enzymes in bacteria catalyze these two reactions. In this review, we briefly summarize its source and function, improvement of the conversion rate of penicillin to deacetyloxycephalosporin C through enzyme modification, crystallography features, the prediction of the active site, and application perspective.
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Affiliation(s)
- Xiaofan Niu
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Jian Zhang
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.,Tianjin Microbial Metabolism and Fermentation Process Control Technology Engineering Center, Tianjin, 300457, China
| | - Xianli Xue
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.,Tianjin Microbial Metabolism and Fermentation Process Control Technology Engineering Center, Tianjin, 300457, China
| | - Depei Wang
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.,National Demonstration Center for Experimental Bioengineering Education (Tianjin University of Science and Technology), Tianjin, 300457, China.,Tianjin Microbial Metabolism and Fermentation Process Control Technology Engineering Center, Tianjin, 300457, China
| | - Lin Wang
- College of Artificial Intelligence, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Qiang Gao
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.,National Demonstration Center for Experimental Bioengineering Education (Tianjin University of Science and Technology), Tianjin, 300457, China.,Tianjin Microbial Metabolism and Fermentation Process Control Technology Engineering Center, Tianjin, 300457, China
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Galanie S, Entwistle D, Lalonde J. Engineering biosynthetic enzymes for industrial natural product synthesis. Nat Prod Rep 2021; 37:1122-1143. [PMID: 32364202 DOI: 10.1039/c9np00071b] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Covering: 2000 to 2020 Natural products and their derivatives are commercially important medicines, agrochemicals, flavors, fragrances, and food ingredients. Industrial strategies to produce these structurally complex molecules encompass varied combinations of chemical synthesis, biocatalysis, and extraction from natural sources. Interest in engineering natural product biosynthesis began with the advent of genetic tools for pathway discovery. Genes and strains can now readily be synthesized, mutated, recombined, and sequenced. Enzyme engineering has succeeded commercially due to the development of genetic methods, analytical technologies, and machine learning algorithms. Today, engineered biosynthetic enzymes from organisms spanning the tree of life are used industrially to produce diverse molecules. These biocatalytic processes include single enzymatic steps, multienzyme cascades, and engineered native and heterologous microbial strains. This review will describe how biosynthetic enzymes have been engineered to enable commercial and near-commercial syntheses of natural products and their analogs.
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Affiliation(s)
- Stephanie Galanie
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.
| | - David Entwistle
- Process Chemistry, Codexis, Inc., Redwood City, California, USA
| | - James Lalonde
- Microbial Digital Genome Engineering, Inscripta, Inc., Pleasanton, California, USA
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Abstract
C–H functionalization is a chemically challenging but highly desirable transformation. 2-oxoglutarate-dependent oxygenases (2OGXs) are remarkably versatile biocatalysts for the activation of C–H bonds. In nature, they have been shown to accept both small and large molecules carrying out a plethora of reactions, including hydroxylations, demethylations, ring formations, rearrangements, desaturations, and halogenations, making them promising candidates for industrial manufacture. In this review, we describe the current status of 2OGX use in biocatalytic applications concentrating on 2OGX-catalyzed oxyfunctionalization of amino acids and synthesis of antibiotics. Looking forward, continued bioinformatic sourcing will help identify additional, practical useful members of this intriguing enzyme family, while enzyme engineering will pave the way to enhance 2OGX reactivity for non-native substrates.
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Rabe P, Kamps JJAG, Schofield CJ, Lohans CT. Roles of 2-oxoglutarate oxygenases and isopenicillin N synthase in β-lactam biosynthesis. Nat Prod Rep 2018; 35:735-756. [PMID: 29808887 PMCID: PMC6097109 DOI: 10.1039/c8np00002f] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Indexed: 01/01/2023]
Abstract
Covering: up to 2017 2-Oxoglutarate (2OG) dependent oxygenases and the homologous oxidase isopenicillin N synthase (IPNS) play crucial roles in the biosynthesis of β-lactam ring containing natural products. IPNS catalyses formation of the bicyclic penicillin nucleus from a tripeptide. 2OG oxygenases catalyse reactions that diversify the chemistry of β-lactams formed by both IPNS and non-oxidative enzymes. Reactions catalysed by the 2OG oxygenases of β-lactam biosynthesis not only involve their typical hydroxylation reactions, but also desaturation, epimerisation, rearrangement, and ring-forming reactions. Some of the enzymes involved in β-lactam biosynthesis exhibit remarkable substrate and product selectivities. We review the roles of 2OG oxygenases and IPNS in β-lactam biosynthesis, highlighting opportunities for application of knowledge of their roles, structures, and mechanisms.
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Affiliation(s)
- Patrick Rabe
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Jos J A G Kamps
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Christopher J Schofield
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Christopher T Lohans
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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Fan K, Lin B, Tao Y, Yang K. Engineering deacetoxycephalosporin C synthase as a catalyst for the bioconversion of penicillins. J Ind Microbiol Biotechnol 2016; 44:705-710. [PMID: 27826726 DOI: 10.1007/s10295-016-1857-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/30/2016] [Indexed: 11/27/2022]
Abstract
7-aminodeacetoxycephalosporanic acid (7-ADCA) is a key intermediate of many clinically useful semisynthetic cephalosporins that were traditionally prepared by processes involving chemical ring expansion of penicillin G. Bioconversion of penicillins to cephalosporins using deacetoxycephalosporin C synthase (DAOCS) is an alternative and environmentally friendly process for 7-ADCA production. Arnold Demain and co-workers pioneered such a process. Later, protein engineering efforts to improve the substrate specificity and catalytic efficiency of DAOCS for penicillins have been made by many groups, and a whole cell process using Escherichia coli for bioconversion of penicillins has been developed.
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Affiliation(s)
- Keqiang Fan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road, Beijing, 100101, People's Republic of China
| | - Baixue Lin
- ASCR Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Yong Tao
- ASCR Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Keqian Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road, Beijing, 100101, People's Republic of China.
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9
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Modified Deacetylcephalosporin C Synthase for the Biotransformation of Semisynthetic Cephalosporins. Appl Environ Microbiol 2016; 82:3711-3720. [PMID: 27084018 DOI: 10.1128/aem.00174-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/06/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Deacetylcephalosporin C synthase (DACS), a 2-oxoglutarate-dependent oxygenase synthesized by Streptomyces clavuligerus, transforms an inert methyl group of deacetoxycephalosporin C (DAOC) into an active hydroxyl group of deacetylcephalosporin C (DAC) during the biosynthesis of cephalosporin. It is a step which is chemically difficult to accomplish, but its development by use of an enzymatic method with DACS can facilitate a cost-effective technology for the manufacture of semisynthetic cephalosporin intermediates such as 7-amino-cephalosporanic acid (7ACA) and hydroxymethyl-7-amino-cephalosporanic acid (HACA) from cephalosporin G. As the native enzyme showed negligible activity toward cephalosporin G, an unnatural and less expensive substrate analogue, directed-evolution strategies such as random, semirational, rational, and computational methods were used for systematic engineering of DACS for improved activity. In comparison to the native enzyme, several variants with improved catalytic efficiency were found. The enzyme was stable for several days and is expressed in soluble form at high levels with significantly higher kcat/Km values. The efficacy and industrial scalability of one of the selected variants, CefFGOS, were demonstrated in a process showing complete bioconversion of 18 g/liter of cephalosporin G into deacetylcephalosporin G (DAG) in about 80 min and showed reproducible results at higher substrate concentrations as well. DAG could be converted completely into HACA in about 30 min by a subsequent reaction, thus facilitating scalability toward commercialization. The experimental findings with several mutants were also used to rationalize the functional conformation deduced from homology modeling, and this led to the disclosure of critical regions involved in the catalysis of DACS. IMPORTANCE 7ACA and HACA serve as core intermediates for the manufacture of several semisynthetic cephalosporins. As they are expensive, a cost-effective enzyme technology for the manufacture of these intermediates is required. Deacetylcephalosporin C synthase (DACS) was identified as a candidate enzyme for the development of technology from cephalosporin G in this study. Directed-evolution strategies were employed to enhance the catalytic efficiency of deacetylcephalosporin C synthase. One of the selected mutants of deacetylcephalosporin C synthase could convert high concentrations of cephalosporin G into DAG, which subsequently could be converted into HACA completely. As cephalosporin G is inexpensive and readily available, the technology would lead to a substantial reduction in the cost for these intermediates upon commercialization.
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10
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Andersson I, Valegård K. 2-Oxoglutarate-Dependent Oxygenases of Cephalosporin Synthesis. 2-OXOGLUTARATE-DEPENDENT OXYGENASES 2015. [DOI: 10.1039/9781782621959-00385] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Central steps in the biosynthetic pathways of some of the most commonly used antibiotics, the cephalosporins, are catalysed by 2-oxoglutarate (2OG)-dependent oxygenases. Deacetoxycephalosporin C synthase (DAOCS) catalyses the 2OG-dependent oxidative expansion of the five-membered thiazolidine ring of the penicillin nucleus into the six-membered dihydrothiazine ring of the cephalosporin nucleus. DAOCS uses dioxygen to create a reactive iron–oxygen intermediate from ferrous ion to drive the reaction. In prokaryotic cephalosporin producers, the cephalosporin product, DAOC, is hydroxylated at the 3′-position to form deacetylcephalosporin C (DAC) as catalysed by a second 2OG-dependent enzyme, DAC synthase (DACS). In eukaryotic cephalosporin producers, the reaction is catalysed by a bifunctional enzyme, DAOC/DACS, that catalyses both the ring expansion and the 3′-hydroxylation reactions. The prokaryotic and eukaryotic enzymes are closely related to DAOCS by sequence, suggesting these enzymes may have evolved by gene duplication. Cephamycin C-producing microorganisms use two enzymes, encoded by the genes cmcI/J, to convert cephalosporins to their 7α-methoxy derivatives that are less vulnerable to β-lactam hydrolysing enzymes. The methoxylation reaction is dependent on Fe(ii), 2OG and S-adenosylmethionine, suggesting the involvement of another 2OG-dependent oxygenase. Herein, structural and mechanistic features are summarized for these 2OG enzymes that utilize this common and flexible mode of dioxygen activation.
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Affiliation(s)
- Inger Andersson
- Department of Cell and Molecular Biology, Uppsala University Box 596, S-751 24 Uppsala Sweden
| | - Karin Valegård
- Department of Cell and Molecular Biology, Uppsala University Box 596, S-751 24 Uppsala Sweden
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11
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Tarhonskaya H, Szöllössi A, Leung IKH, Bush JT, Henry L, Chowdhury R, Iqbal A, Claridge TDW, Schofield CJ, Flashman E. Studies on Deacetoxycephalosporin C Synthase Support a Consensus Mechanism for 2-Oxoglutarate Dependent Oxygenases. Biochemistry 2014; 53:2483-93. [DOI: 10.1021/bi500086p] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Hanna Tarhonskaya
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Andrea Szöllössi
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Ivanhoe K. H. Leung
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Jacob T. Bush
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Luc Henry
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Rasheduzzaman Chowdhury
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Aman Iqbal
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Timothy D. W. Claridge
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Christopher J. Schofield
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Emily Flashman
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, United Kingdom
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12
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Hüttel W. Biocatalytic Production of Chemical Building Blocks in Technical Scale with α-Ketoglutarate-Dependent Dioxygenases. CHEM-ING-TECH 2013. [DOI: 10.1002/cite.201300008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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13
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Recent advances in the biosynthesis of penicillins, cephalosporins and clavams and its regulation. Biotechnol Adv 2013; 31:287-311. [DOI: 10.1016/j.biotechadv.2012.12.001] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 11/30/2012] [Accepted: 12/01/2012] [Indexed: 11/23/2022]
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14
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Iterative combinatorial mutagenesis as an effective strategy for generation of deacetoxycephalosporin C synthase with improved activity toward penicillin G. Appl Environ Microbiol 2012; 78:7809-12. [PMID: 22923414 DOI: 10.1128/aem.02122-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An iterative combinatorial mutagenesis (ICM) strategy was used to engineer deacetoxycephalosporin C synthase of Streptomyces clavuligerus (scDAOCS) for improved activity toward penicillin G. Seven mutational sites were repeatedly combined onto a starter mutant (C155Y Y184H V275I C281Y) of scDAOCS. Eleven improved combinatorial mutants were identified from 24 mutants in four rounds of ICM.
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15
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Ji J, Tian X, Fan K, Yang K. New strategy of site-directed mutagenesis identifies new sites to improve Streptomyces clavuligerus deacetoxycephalosporin C synthase activity toward penicillin G. Appl Microbiol Biotechnol 2011; 93:2395-401. [DOI: 10.1007/s00253-011-3566-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 08/10/2011] [Accepted: 08/29/2011] [Indexed: 10/17/2022]
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16
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Wu XB, Tian XY, Ji JJ, Wu WB, Fan KQ, Yang KQ. Saturation mutagenesis of Acremonium chrysogenum deacetoxy/deacetylcephalosporin C synthase R308 site confirms its role in controlling substrate specificity. Biotechnol Lett 2010; 33:805-12. [DOI: 10.1007/s10529-010-0504-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 12/08/2010] [Indexed: 11/27/2022]
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17
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18
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Ruiz B, Chávez A, Forero A, García-Huante Y, Romero A, Sánchez M, Rocha D, Sánchez B, Rodríguez-Sanoja R, Sánchez S, Langley E. Production of microbial secondary metabolites: regulation by the carbon source. Crit Rev Microbiol 2010; 36:146-67. [PMID: 20210692 DOI: 10.3109/10408410903489576] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Microbial secondary metabolites are low molecular mass products, not essential for growth of the producing cultures, but very important for human health. They include antibiotics, antitumor agents, cholesterol-lowering drugs, and others. They have unusual structures and are usually formed during the late growth phase of the producing microorganisms. Its synthesis can be influenced greatly by manipulating the type and concentration of the nutrients formulating the culture media. Among these nutrients, the effect of the carbon sources has been the subject of continuous studies for both, industry and research groups. Different mechanisms have been described in bacteria and fungi to explain the negative carbon catabolite effects on secondary metabolite production. Their knowledge and manipulation have been useful either for setting fermentation conditions or for strain improvement. During the last years, important advances have been reported on these mechanisms at the biochemical and molecular levels. The aim of the present review is to describe these advances, giving special emphasis to those reported for the genus Streptomyces.
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Affiliation(s)
- Beatriz Ruiz
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, México
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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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Directed evolution and rational approaches to improving Streptomyces clavuligerus deacetoxycephalosporin C synthase for cephalosporin production. J Ind Microbiol Biotechnol 2009; 36:619-33. [DOI: 10.1007/s10295-009-0549-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Accepted: 02/12/2009] [Indexed: 10/21/2022]
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21
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Chen J, Li W, Wang M, Zhu G, Liu D, Sun F, Hao N, Li X, Rao Z, Zhang XC. Crystal structure and mutagenic analysis of GDOsp, a gentisate 1,2-dioxygenase from Silicibacter pomeroyi. Protein Sci 2008; 17:1362-73. [PMID: 18505738 DOI: 10.1110/ps.035881.108] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Dioxygenases catalyze dioxygen incorporation into various organic compounds and play a key role in the complex degradation pathway of mono- and polycyclic aromatic and hetero-aromatic compounds. Here we report the crystal structure of gentisate 1,2-dioxygenase from Silicibacter pomeroyi (GDOsp) at a 2.8 A resolution. The enzyme possessed a conserved three-dimensional structure of the bicupin family, forming a homotetramerization. However, each subunit of GDOsp unusually contained two ferrous centers that were located in its two homologous cupin domains, respectively. Further mutagenic analysis indicated that the enzyme activity of GDOsp depends on the microenvironment in both metal-binding sites. Moreover, homologous structural comparison and functional study on GDOsp variants unveiled a group of functionally essential residues and suggested that the active site of the enzyme is located in the amino-terminal domain, but could be influenced by changes in the carboxyl domain. Therefore, GDOsp may provide a working model for studying long-distance communication within a protein (or its complex).
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Affiliation(s)
- Jia Chen
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People's Republic of China
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22
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Sim Goo K, Song Chua C, Sim TS. A complete library of amino acid alterations at R306 in Streptomyces clavuligerus deacetoxycephalosporin C synthase demonstrates its structural role in the ring-expansion activity. Proteins 2008; 70:739-47. [PMID: 17729280 DOI: 10.1002/prot.21549] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In a previous study, the conserved arginine residue at position 306 of Streptomyces clavuligerus deacetoxycephalsoporin C synthase (scDAOCS), when mutated to leucine, resulted in 191% increase in converting ampicillin to its expanded cephalosporin moiety compared with that of the wild-type enzyme. However, the role of this residue in eliciting the improved enzymatic activity is not well understood. In this study, probing the molecular basis of amino acid substitutions at position 306 has underscored its importance for engineering various improvements in the ring expansion activity. Structural modeling using SwissPdbViewer revealed that R306 is surrounded by a hydrophobic cleft formed by residues Y184, L186, W297, I298, and V303. Hence, the improved activity achieved by the R306L mutation was probably because of better hydrophobic packing in this region. To evaluate the role of amino acids at position 306 of scDAOCS and its influence on the molecular status of the enzyme at this locality, alteration to 18 other amino acids was done by site-directed mutagenesis. The effects of each substitution on the enzyme activity were determined by bioassay using penicillin substrates: ampicillin, penicillin G, phenethicillin, and carbenicillin. Results obtained showed a drastic reduction in enzyme activity when R306 was replaced with charged or polar residues, thus emphasizing the importance of hydrophobic packing around this site. The bioassay results also illustrated that apart from leucine, substitutions to nonpolar residues, isoleucine and methionine, were able to improve the ampicillin conversion activity of scDAOCS by 168 and 113% of the wild-type enzyme activity, respectively. Similar trend of effects from each mutation was also observed for penicillin G, phenethicillin, and carbenicillin conversions. The enhanced enzyme activities were supported by spectrophotometric assay indicating that all these mutants have lower K(m) values (R306L: 1.09 mM; R306I: 2.64 mM; R306M: 5.68 mM) than the wild-type enzyme (8.33 mM), resulting in improvement in the enzyme's substrate binding affinity. Hence, this mutational study of amino acids situated at 306 of scDAOCS has provided a better understanding of the significance of specific amino acid residues at this position which can improve its ring-expansion activity when given a plethora of beta-lactam substrates to generate corresponding, possibly new, cephalosporins.
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Affiliation(s)
- Kian Sim Goo
- Department of Microbiology, Yong Loo Lin School of Medicine, Singapore 117597
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23
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Relevant double mutations in bioengineered Streptomyces clavuligerus deacetoxycephalosporin C synthase result in higher binding specificities which improve penicillin bioconversion. Appl Environ Microbiol 2007; 74:1167-75. [PMID: 18083859 DOI: 10.1128/aem.02230-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptomyces clavuligerus deacetoxycephalosporin C synthase (ScDAOCS) is an important industrial enzyme for the production of 7-aminodeacetoxycephalosporanic acid, which is a precursor for cephalosporin synthesis. Single mutations of six amino acid residues, V275, C281, N304, I305, R306, and R307, were previously shown to result in enhanced levels of ampicillin conversion, with activities ranging from 129 to 346% of the wild-type activity. In this study, these mutations were paired to investigate their effects on enzyme catalysis. The bioassay results showed that the C-terminal mutations (N304X [where X is alanine, leucine, methionine, lysine, or arginine], I305M, R306L, and R307L) in combination with C281Y substantially increased the conversion of ampicillin; the activity was up to 491% of the wild-type activity. Similar improvements were observed for converting carbenicillin (up to 1,347% of the wild-type activity) and phenethicillin (up to 1,109% of the wild-type activity). Interestingly, the N304X R306L double mutants exhibited lower activities for penicillin G conversion, and activities that were 40 to 114% of wild-type enzyme activity were detected. Based on kinetic studies using ampicillin, it was clear that the increases in the activities of the double mutants relative to those of the corresponding single mutants were due to enhanced substrate binding affinities. These results also validated the finding that the N304R and I305M mutations are ideal for increasing the substrate binding affinity and turnover rate of the enzyme, respectively. This study provided further insight into the structure-function interaction of ScDAOCS with different penicillin substrates, thus providing a useful platform for further rational modification of its enzymatic properties.
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Schlosrich J, Eley KL, Crowley PJ, Bugg TDH. Directed Evolution of a Non-Heme-Iron-Dependent Extradiol Catechol Dioxygenase: Identification of Mutants with Intradiol Oxidative Cleavage Activity. Chembiochem 2006; 7:1899-908. [PMID: 17051653 DOI: 10.1002/cbic.200600296] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The non-heme-iron(II)-dependent extradiol catechol dioxygenases catalyse the oxidative cleavage of substituted catechols found on bacterial aromatic degradation pathways. The reaction mechanism of the extradiol dioxygenases is believed to proceed through the same proximal hydroperoxide intermediate as the iron(III)-dependent intradiol catechol dioxygenases. Directed evolution was carried out on members of the class III extradiol catechol dioxygenases, by using 1) error-prone polymerase chain reaction, 2) a primer-based cross-over method; the mutant dioxygenases were then screened for their ability to process a range of substituted catechols. Several mutant enzymes were found to show higher activity towards certain substituted catechols, including 4-chlorocatechol, and higher affinity for the iron(II) cofactor. Two mutants isolated from error-prone PCR of Escherichia coli MhpB (mutants R215W and K273R) were found to produce a mixture of extradiol and intradiol cleavage products, as detected by GC-MS and 1H NMR spectroscopy. The residue corresponding to K273 in protocatechuate 4,5-dioxygenase (LigAB), Val244, is located approximately 12 A from the iron(II) centre, but close to the putative dioxygen channel; R215 is found on a sequence loop not present in LigB.
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Affiliation(s)
- Janne Schlosrich
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
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26
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Stok JE, Baldwin JE. Development of enzyme-linked immunosorbent assays for the detection of deacetoxycephalosporin C and isopenicillin N synthase activity. Anal Chim Acta 2006; 577:153-62. [PMID: 17723666 DOI: 10.1016/j.aca.2006.06.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Revised: 06/13/2006] [Accepted: 06/16/2006] [Indexed: 10/24/2022]
Abstract
Although there are a number of existing assays for monitoring the activity of both isopenicillin N synthase (IPNS) and deacetoxycephalosporin C synthase (DAOCS), none have demonstrated the qualities required for screening a mutant library. Hence, enzyme-linked immunosorbent assays (ELISAs) for IPNS and DAOCS were developed based on the detection of the catalytic turnover products isopenicillin N and cephalexin/phenylacetyl-7-aminodeacetoxycephalosporanic acid (G-7-ADCA), respectively. These assays are relatively fast compared to existing assays, such as the hole-plate bioassay, and are amenable with high-throughput screening. Both the IPNS and DAOCS-ELISAs were optimised for use with crude protein extracts rather than purified protein, thereby eliminating any additional time required for purification. The ELISA developed for the detection of cephalexin had an IC50 value of 154+/-9 ng mL(-1) and LOD of 7.2+/-2.2 ng mL(-1) under conditions required for the assay. Good recoveries and correlation was observed for spiked samples when the concentration of crude protein was kept below 1 mg mL(-1). The DAOCS-ELISA was found to have increased sensitivity compared to the hole-plate bioassay (10.3 microg mL(-1)). The IPNS-ELISA did not significantly increase the sensitivity (approximately 5 microg mL(-1)) compared to that of the hole-plate bioassay (16 microg mL(-1)) for isopenicillin N. The minimum amount of crude protein extract required for producing detectable amounts of product for both assays was below 0.5% of the maximum amount of protein that the assay could contain without any effect on the ELISA. This suggests that when screening a mutant library, mutants producing low amounts of the product could still be detected using these assays.
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Affiliation(s)
- Jeanette E Stok
- Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom.
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27
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Chiu WC, You JY, Liu JS, Hsu SK, Hsu WH, Shih CH, Hwang JK, Wang WC. Structure-stability-activity relationship in covalently cross-linked N-carbamoyl D-amino acid amidohydrolase and N-acylamino acid racemase. J Mol Biol 2006; 359:741-53. [PMID: 16650857 DOI: 10.1016/j.jmb.2006.03.063] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 03/27/2006] [Accepted: 03/30/2006] [Indexed: 11/24/2022]
Abstract
N-Acylamino acid racemase (NAAAR) and N-carbamoyl-D-amino-acid amidohydrolase (D-NCAase) are important biocatalysts for producing enantiopure alpha-amino acids. NAAAR forms an octameric assembly and displays induced fit movements upon substrate binding, while D-NCAase is a tetramer that does not change conformation in the presence of a ligand. To investigate the effects of introducing potentially stabilizing S-S bridges in these different multimeric enzymes, cysteine residues predicted to form inter or intra-subunit disulfide bonds were introduced by site-directed mutagenesis. Inter-subunit S-S bonds were formed in two NAAAR variants (A68C-D72C and P60C-Y100C) and two d-NCAase variants (A302C and P295C-F304C). Intra-subunit S-S bonds were formed in two additional NAAAR variants (E149C-A182C and V265C). Crystal structures of NAAARs variants show limited deviations from the wild-type overall tertiary structure. An apo A68C-D72C subunit differs from the wild-type enzyme, in which it has an ordered lid loop, resembling ligand-bound NAAAR. The structures of A222C and A302C D-NCAases are nearly identical to the wild-type enzyme. All mutants with inter-subunit bridges had increases in thermostability. Compared with the wild-type enzyme, A68C-D72C NAAAR showed similar kcat/Km ratios, whereas mutant D-NCAases demonstrated increased kcat/Km ratios at high temperatures (A302C: 4.2-fold at 65 degrees C). Furthermore, molecular dynamic simulations reveal that A302C substantially sustains the fine-tuned catalytic site as temperature increases, achieving enhanced activity.
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Affiliation(s)
- Wei-Chun Chiu
- Institute of Molecular and Cellular Biology & Department of Life Science, National Tsing Hua University, HsinChu, Taiwan, 30013, ROC
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28
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Wei CL, Yang YB, Deng CH, Liu WC, Hsu JS, Lin YC, Liaw SH, Tsai YC. Directed evolution of Streptomyces clavuligerus deacetoxycephalosporin C synthase for enhancement of penicillin G expansion. Appl Environ Microbiol 2006; 71:8873-80. [PMID: 16332884 PMCID: PMC1317366 DOI: 10.1128/aem.71.12.8873-8880.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The deacetoxycephalosporin C synthase from Streptomyces clavuligerus was directly modified for enhancement of penicillin G expansion into phenylacetyl-7-aminodeacetoxycephalosporanic acid, an important intermediate in the industrial manufacture of cephalosporin antibiotics. Nine new mutants, mutants M73T, T91A, A106T, C155Y, Y184H, M188V, M188I, H244Q, and L277Q with 1.4- to 5.7-fold increases in the kcat/Km ratio, were obtained by screening 6,364 clones after error-prone PCR-based random mutagenesis. Subsequently, DNA shuffling was carried out to screen possible combinations of substitutions, including previous point mutations. One quaternary mutant, the C155Y/Y184H/V275I/C281Y mutant, which had a kcat/Km ratio that was 41-fold higher was found after 10,572 clones were assayed. The distinct mutants obtained using different mutagenesis methods demonstrated the complementarity of the techniques. Interestingly, most of the mutated residues that result in enhanced activities are located within or near the unique small barrel subdomain, suggesting that manipulation of this subdomain may be a constructive strategy for improvement of penicillin expansion. Several mutations had very distinct effects on expansion of penicillins N and G, perhaps due to different penicillin-interacting modes within the enzyme. Thus, the present study provided not only promising enzymes for cephalosporin biosynthesis but also a large number of mutants, which provided new insights into the structure-function relationship of the protein that should lead to further rational engineering.
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Affiliation(s)
- Chia-Li Wei
- Institute of Biochemistry, National Yang-Ming University, 155, Sec. 2, Li-Nong St., Pei-Tou, Taipei 11221, Taiwan
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29
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Wu XB, Fan KQ, Wang QH, Yang KQ. C-terminus mutations of Acremonium chrysogenum deacetoxy/deacetylcephalosporin C synthase with improved activity toward penicillin analogs. FEMS Microbiol Lett 2005; 246:103-10. [PMID: 15869968 DOI: 10.1016/j.femsle.2005.03.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2004] [Revised: 03/16/2005] [Accepted: 03/26/2005] [Indexed: 10/25/2022] Open
Abstract
Deacetoxy/deacetylcephalosporin C synthase (acDAOC/DACS) from Acremonium chrysogenum is a bifunctional enzyme that catalyzes both the ring-expansion of penicillin N to deacetoxycephalosporin C (DAOC) and the hydroxylation of the latter to deacetylcephalosporin C (DAC). Three residues N305, R307 and R308 located in close proximity to the C-terminus of acDAOC/DACS were each mutated to leucine. The N305L and R308L mutant acDAOC/DACSs showed significant improvement in their ability to convert penicillin analogs. R308 was identified for the first time as a critical residue for DAOC/DACS activity. Kinetic analyses of purified R308L enzyme indicated its improved catalytic efficiency is due to combined improvements of K(m) and k(cat). Comparative modeling of acDAOC/DACS supports the involvement of R308 in the formation of substrate-binding pocket.
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Affiliation(s)
- Xiao-Bin Wu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, PR China
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30
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Hsu JS, Yang YB, Deng CH, Wei CL, Liaw SH, Tsai YC. Family shuffling of expandase genes to enhance substrate specificity for penicillin G. Appl Environ Microbiol 2004; 70:6257-63. [PMID: 15466573 PMCID: PMC522083 DOI: 10.1128/aem.70.10.6257-6263.2004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Deacetoxycephalosporin C synthase (expandase) from Streptomyces clavuligerus, encoded by cefE, is an important industrial enzyme for the production of 7-aminodeacetoxycephalosporanic acid from penicillin G. To improve the substrate specificity for penicillin G, eight cefE-homologous genes were directly evolved by using the DNA shuffling technique. After the first round of shuffling and screening, using an Escherichia coli ESS bioassay, four chimeras with higher activity were subjected to a second round. Subsequently, 20 clones were found with significantly enhanced activity. The kinetic parameters of two isolates that lack substrate inhibition showed 8.5- and 118-fold increases in the k(cat)/K(m) ratio compared to the S. clavuligerus expandase. The evolved enzyme with the 118-fold increase is the most active obtained to date anywhere. Our shuffling results also indicate the remarkable plasticity of the expandase, suggesting that more-active chimeras might be achievable with further rounds.
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Affiliation(s)
- Jyh-Shing Hsu
- Institute of Biochemistry, National Yang-Ming University, 155 Li-Nong St., Sec. 2, Pei-Tou, Taipei 11221, Taiwan
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31
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Oster LM, van Scheltinga ACT, Valegård K, Hose AM, Dubus A, Hajdu J, Andersson I. Conformational Flexibility of the C Terminus with Implications for Substrate Binding and Catalysis Revealed in a New Crystal Form of Deacetoxycephalosporin C Synthase. J Mol Biol 2004; 343:157-71. [PMID: 15381427 DOI: 10.1016/j.jmb.2004.07.049] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Revised: 07/12/2004] [Accepted: 07/15/2004] [Indexed: 11/18/2022]
Abstract
Deacetoxycephalosporin C synthase (DAOCS) from Streptomyces clavuligerus catalyses the oxidative ring expansion of the penicillin nucleus into the nucleus of cephalosporins. The reaction requires dioxygen and 2-oxoglutarate as co-substrates to create a reactive iron-oxygen intermediate from a ferrous iron in the active site. The active enzyme is monomeric in solution. The structure of DAOCS was determined earlier from merohedrally twinned crystals where the last four C-terminal residues (308-311) of one molecule penetrate the active site of a neighbouring molecule, creating a cyclic trimeric structure in the crystal. Shortening the polypeptide chain from the C terminus by more than four residues diminishes activity. Here, we describe a new crystal form of DAOCS in which trimer formation is broken and the C-terminal arm is free. These crystals show no signs of twinning, and were obtained from DAOCS labelled with an N-terminal His-tag. The modified DAOCS is catalytically active. The free C-terminal arm protrudes into the solvent, and the C-terminal domain (residues 268-299) is rotated by about 16 degrees towards the active site. The last 12 residues (300-311) are disordered. Structures for various enzyme-substrate and enzyme-product complexes in the new crystal form confirm overlapping binding sites for penicillin and 2-oxoglutarate. The results support the notion that 2-oxoglutarate and dioxygen need to react first to produce an oxidizing iron species, followed by reaction with the penicillin substrate. The position of the penicillin nucleus is topologically similar in the two crystal forms, but the penicillin side-chain in the new non-twinned crystals overlaps with the position of residues 304-306 of the C-terminal arm in the twinned crystals. An analysis of the interactions between the C-terminal region and residues in the active site indicates that DAOCS could also accept polypeptide chains as ligands, and these could bind near the iron.
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Affiliation(s)
- Linda M Oster
- Department of Molecular Biology, Swedish University of Agricultural Sciences, Box 590, S-75124 Uppsala
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Chin HS, Goo KS, Sim TS. A complete library of amino acid alterations at N304 in Streptomyces clavuligerus deacetoxycephalosporin C synthase elucidates the basis for enhanced penicillin analogue conversion. Appl Environ Microbiol 2004; 70:607-9. [PMID: 14711695 PMCID: PMC321265 DOI: 10.1128/aem.70.1.607-609.2004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
N304 of Streptomyces clavuligerus deacetoxycephalosporin C synthase was mutagenized to alter its catalytic ability. Given that N304A, N304K, N304L, and N304R mutant enzymes exhibited significant improvements in penicillin analogue conversions, we advocate that replacement of N304 with residues with aliphatic or basic side chains is preferable for engineering of a hypercatalytic enzyme.
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Affiliation(s)
- Hong Soon Chin
- Department of Microbiology, Faculty of Medicine, Tropical Marine Science Institute, National University of Singapore, Singapore
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