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Liu Y, Yue SJ, Wang W, Hu HB, Zhang XH. Elucidation of the Biosynthesis of Griseoluteic Acid in Streptomyces griseoluteus P510. JOURNAL OF NATURAL PRODUCTS 2024; 87:1540-1547. [PMID: 38832657 DOI: 10.1021/acs.jnatprod.4c00017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
Phenazines are aromatic compounds with antifungal and cytotoxic activities. Phenazines incorporating phenazine 1-carboxylic acid have widespread applications in agriculture, medicine, and industry. Griseoluteic acid is a cytotoxic compound secreted by Streptomyces griseoluteus P510, displaying potential medical applications. However, the biosynthetic pathway of griseoluteic acid has not been elucidated, limiting its development and application. In this study, a conserved phenazine biosynthetic gene cluster of S. griseoluteus P510 was identified through genomic analysis. Subsequently, its was confirmed that the four essential modification enzymes SgpH, SgpI, SgpK, and SgpL convert phenazine-1,6-dicarboxylic acid into griseoluteic acid by heterologous expression in Escherichia coli. Moreover, the biosynthetic pathway of griseoluteic acid was established in Pseudomonas chlororaphis characterized by a high growth rate and synthesis efficiency of phenazines, laying the foundation for the efficient production of griseoluteic acid.
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Affiliation(s)
- Ying Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Sheng-Jie Yue
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Wei Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Hong-Bo Hu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
- National Experimental Teaching Center for Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Xue-Hong Zhang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
- National Experimental Teaching Center for Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
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2
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Chen M, Pang B, Ding W, Zhao Q, Tang Z, Liu W. Investigation of 2,2'-Bipyridine Biosynthesis Reveals a Common Two-Component System for Aldehydes Production by Carboxylate Reduction. Org Lett 2022; 24:897-902. [PMID: 35044177 DOI: 10.1021/acs.orglett.1c04239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here, we report a two-component enzymatic system that efficiently catalyzes the reduction of a carboxylate to an aldehyde in the biosynthesis of 2,2'-bipyridine antibiotics caerulomycins. The associated paradigm involves the activation of carboxylate by ATP-dependent adenylation protein CaeF, followed by its reduction catalyzed by CaeB2, a new class of NADPH-dependent aldehyde dehydrogenase (ALDH) that directly reduces AMP-conjugated carboxylate, which is distinct from the known aldehyde-producing enzymes that reduce ACP- or CoA-conjugated carboxylates.
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Affiliation(s)
- Ming Chen
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Bo Pang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Wenping Ding
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Qunfei Zhao
- Innovation Research Institute of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai 201203, China
| | - Zhijun Tang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Wen Liu
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.,Huzhou Center of Bio-Synthetic Innovation, 1366 Hongfeng Road, Huzhou 313000, China
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3
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de Paiva FCR, Chan K, Samborskyy M, Silber AM, Leadlay PF, Dias MVB. The crystal structure of AjiA1 reveals a novel structural motion mechanism in the adenylate-forming enzyme family. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2020; 76:1201-1210. [DOI: 10.1107/s2059798320013431] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/07/2020] [Indexed: 11/10/2022]
Abstract
Adenylate-forming enzymes (AFEs) are a mechanistic superfamily of proteins that are involved in many cellular roles. In the biosynthesis of benzoxazole antibiotics, an AFE has been reported to play a key role in the condensation of cyclic molecules. In the biosynthetic gene cluster for the benzoxazole AJI9561, AjiA1 catalyzes the condensation of two 3-hydroxyanthranilic acid (3-HAA) molecules using ATP as a co-substrate. Here, the enzymatic activity of AjiA1 is reported together with a structural analysis of its apo form. The structure of AjiA1 was solved at 2.0 Å resolution and shows a conserved fold with other AFE family members. AjiA1 exhibits activity in the presence of 3-HAA (K
m = 77.86 ± 28.36, k
cat = 0.04 ± 0.004) and also with the alternative substrate 3-hydroxybenzoic acid (3-HBA; K
m = 22.12 ± 31.35, k
cat = 0.08 ± 0.005). The structure of AjiA1 in the apo form also reveals crucial conformational changes that occur during the catalytic cycle of this enzyme which have not been described for any other AFE member. Consequently, the results shown here provide insights into this protein family and a new subgroup is proposed for enzymes that are involved in benzoxazole-ring formation.
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4
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Robinson SL, Terlouw BR, Smith MD, Pidot SJ, Stinear TP, Medema MH, Wackett LP. Global analysis of adenylate-forming enzymes reveals β-lactone biosynthesis pathway in pathogenic Nocardia. J Biol Chem 2020; 295:14826-14839. [PMID: 32826316 DOI: 10.1074/jbc.ra120.013528] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 08/07/2020] [Indexed: 12/31/2022] Open
Abstract
Enzymes that cleave ATP to activate carboxylic acids play essential roles in primary and secondary metabolism in all domains of life. Class I adenylate-forming enzymes share a conserved structural fold but act on a wide range of substrates to catalyze reactions involved in bioluminescence, nonribosomal peptide biosynthesis, fatty acid activation, and β-lactone formation. Despite their metabolic importance, the substrates and functions of the vast majority of adenylate-forming enzymes are unknown without tools available to accurately predict them. Given the crucial roles of adenylate-forming enzymes in biosynthesis, this also severely limits our ability to predict natural product structures from biosynthetic gene clusters. Here we used machine learning to predict adenylate-forming enzyme function and substrate specificity from protein sequences. We built a web-based predictive tool and used it to comprehensively map the biochemical diversity of adenylate-forming enzymes across >50,000 candidate biosynthetic gene clusters in bacterial, fungal, and plant genomes. Ancestral phylogenetic reconstruction and sequence similarity networking of enzymes from these clusters suggested divergent evolution of the adenylate-forming superfamily from a core enzyme scaffold most related to contemporary CoA ligases toward more specialized functions including β-lactone synthetases. Our classifier predicted β-lactone synthetases in uncharacterized biosynthetic gene clusters conserved in >90 different strains of Nocardia. To test our prediction, we purified a candidate β-lactone synthetase from Nocardia brasiliensis and reconstituted the biosynthetic pathway in vitro to link the gene cluster to the β-lactone natural product, nocardiolactone. We anticipate that our machine learning approach will aid in functional classification of enzymes and advance natural product discovery.
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Affiliation(s)
- Serina L Robinson
- BioTechnology Institute, University of Minnesota, Saint Paul, Minnesota, USA; Graduate Program in Bioinformatics and Computational Biology, University of Minnesota, Rochester, Minnesota, USA; Graduate Program in Microbiology, Immunology, and Cancer Biology, University of Minnesota, Minneapolis, Minnesota, USA.
| | - Barbara R Terlouw
- Bioinformatics Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Megan D Smith
- BioTechnology Institute, University of Minnesota, Saint Paul, Minnesota, USA; Graduate Program in Microbiology, Immunology, and Cancer Biology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sacha J Pidot
- Department of Microbiology and Immunology at the Doherty Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Timothy P Stinear
- Department of Microbiology and Immunology at the Doherty Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Marnix H Medema
- Bioinformatics Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Lawrence P Wackett
- BioTechnology Institute, University of Minnesota, Saint Paul, Minnesota, USA; Graduate Program in Bioinformatics and Computational Biology, University of Minnesota, Rochester, Minnesota, USA; Graduate Program in Microbiology, Immunology, and Cancer Biology, University of Minnesota, Minneapolis, Minnesota, USA
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5
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Structures of 2-Hydroxyisobutyric Acid-CoA Ligase Reveal Determinants of Substrate Specificity and Describe a Multi-Conformational Catalytic Cycle. J Mol Biol 2019; 431:2747-2761. [DOI: 10.1016/j.jmb.2019.05.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 02/01/2023]
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6
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Greunke C, Duell ER, D’Agostino PM, Glöckle A, Lamm K, Gulder TAM. Direct Pathway Cloning (DiPaC) to unlock natural product biosynthetic potential. Metab Eng 2018; 47:334-345. [DOI: 10.1016/j.ymben.2018.03.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 03/04/2018] [Accepted: 03/11/2018] [Indexed: 12/12/2022]
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7
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Li Z, Du L, Zhang W, Zhang X, Jiang Y, Liu K, Men P, Xu H, Fortman JL, Sherman DH, Yu B, Gao S, Li S. Complete elucidation of the late steps of bafilomycin biosynthesis in Streptomyces lohii. J Biol Chem 2017; 292:7095-7104. [PMID: 28292933 DOI: 10.1074/jbc.m116.751255] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 02/27/2017] [Indexed: 11/06/2022] Open
Abstract
Bafilomycins are an important subgroup of polyketides with diverse biological activities and possible applications as specific inhibitors of vacuolar H+-ATPase. However, the general toxicity and structural complexity of bafilomycins present formidable challenges to drug design via chemical modification, prompting interests in improving bafilomycin activities via biosynthetic approaches. Two bafilomycin biosynthetic gene clusters have been identified, but their post-polyketide synthase (PKS) tailoring steps for structural diversification and bioactivity improvement remain largely unknown. In this study, the post-PKS tailoring pathway from bafilomycin A1 (1)→C1 (2)→B1 (3) in the marine microorganism Streptomyces lohii was elucidated for the first time by in vivo gene inactivation and in vitro biochemical characterization. We found that fumarate is first adenylated by a novel fumarate adenylyltransferase Orf3. Then, the fumaryl transferase Orf2 is responsible for transferring the fumarate moiety from fumaryl-AMP to the 21-hydroxyl group of 1 to generate 2. Last, the ATP-dependent amide synthetase BafY catalyzes the condensation of 2 and 2-amino-3-hydroxycyclopent-2-enone (C5N) produced by the 5-aminolevulinic acid synthase BafZ and the acyl-CoA ligase BafX, giving rise to the final product 3. The elucidation of fumarate incorporation mechanism represents the first paradigm for biosynthesis of natural products containing the fumarate moiety. Moreover, the bafilomycin post-PKS tailoring pathway features an interesting cross-talk between primary and secondary metabolisms for natural product biosynthesis. Taken together, this work provides significant insights into bafilomycin biosynthesis to inform future pharmacological development of these compounds.
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Affiliation(s)
- Zhong Li
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101.,the University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Du
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101.,the University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Zhang
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101
| | - Xingwang Zhang
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101
| | - Yuanyuan Jiang
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101.,the University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kun Liu
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101
| | - Ping Men
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101
| | - Huifang Xu
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101
| | - Jeffrey L Fortman
- the Departments of Medicinal Chemistry, Chemistry, and Microbiology and Immunology, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, and
| | - David H Sherman
- the Departments of Medicinal Chemistry, Chemistry, and Microbiology and Immunology, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, and
| | - Bing Yu
- the State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Song Gao
- the State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Shengying Li
- From the Shandong Provincial Key Laboratory of Synthetic Biology, and CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101,
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8
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Lee TV, Johnson RD, Arcus VL, Lott JS. Prediction of the substrate for nonribosomal peptide synthetase (NRPS) adenylation domains by virtual screening. Proteins 2015; 83:2052-66. [PMID: 26358936 DOI: 10.1002/prot.24922] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 08/19/2015] [Accepted: 08/28/2015] [Indexed: 12/28/2022]
Abstract
Nonribosomal peptide synthetases (NRPSs) synthesize a diverse array of bioactive small peptides, many of which are used in medicine. There is considerable interest in predicting NRPS substrate specificity in order to facilitate investigation of the many "cryptic" NRPS genes that have not been linked to any known product. However, the current sequence similarity-based methods are unable to produce reliable predictions when there is a lack of prior specificity data, which is a particular problem for fungal NRPSs. We conducted virtual screening on the specificity-determining domain of NRPSs, the adenylation domain, and found that virtual screening using experimentally determined structures results in good enrichment of the cognate substrate. Our results indicate that the conformation of the adenylation domain and in particular the conformation of a key conserved aromatic residue is important in determining the success of the virtual screening. When homology models of NRPS adenylation domains of known specificity, rather than experimentally determined structures, were built and used for virtual screening, good enrichment of the cognate substrate was also achieved in many cases. However, the accuracy of the models was key to the reliability of the predictions and there was a large variation in the results when different models of the same domain were used. This virtual screening approach is promising and is able to produce enrichment of the cognate substrates in many cases, but improvements in building and assessing homology models are required before the approach can be reliably applied to these models.
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Affiliation(s)
- T Verne Lee
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Richard D Johnson
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Vickery L Arcus
- Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Department of Biological Sciences, University of Waikato, Hamilton, New Zealand
| | - J Shaun Lott
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Auckland, New Zealand
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9
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Blankenfeldt W, Parsons JF. The structural biology of phenazine biosynthesis. Curr Opin Struct Biol 2014; 29:26-33. [PMID: 25215885 DOI: 10.1016/j.sbi.2014.08.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/25/2014] [Indexed: 01/28/2023]
Abstract
The phenazines are a class of over 150 nitrogen-containing aromatic compounds of bacterial and archeal origin. Their redox properties not only explain their activity as broad-specificity antibiotics and virulence factors but also enable them to function as respiratory pigments, thus extending their importance to the primary metabolism of phenazine-producing species. Despite their discovery in the mid-19th century, the molecular mechanisms behind their biosynthesis have only been unraveled in the last decade. Here, we review the contribution of structural biology that has led to our current understanding of phenazine biosynthesis.
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Affiliation(s)
- Wulf Blankenfeldt
- Helmholtz Centre for Infection Research, Structure and Function of Proteins, Inhoffenstr. 7, 38124 Braunschweig, Germany.
| | - James F Parsons
- Institute for Bioscience and Biotechnology Research, University of Maryland, 9600 Gudelsky Drive, Rockville, MD 20850, USA.
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10
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Rui Z, Ye M, Wang S, Fujikawa K, Akerele B, Aung M, Floss HG, Zhang W, Yu TW. Insights into a divergent phenazine biosynthetic pathway governed by a plasmid-born esmeraldin gene cluster. ACTA ACUST UNITED AC 2014; 19:1116-25. [PMID: 22999880 DOI: 10.1016/j.chembiol.2012.07.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 07/20/2012] [Accepted: 07/24/2012] [Indexed: 11/25/2022]
Abstract
Phenazine-type metabolites arise from either phenazine-1-carboxylic acid (PCA) or phenazine-1,6-dicarboxylic acid (PDC). Although the biosynthesis of PCA has been studied extensively, PDC assembly remains unclear. Esmeraldins and saphenamycin, the PDC originated products, are antimicrobial and antitumor metabolites isolated from Streptomyces antibioticus Tü 2706. Herein, the esmeraldin biosynthetic gene cluster was identified on a dispensable giant plasmid. Twenty-four putative esm genes were characterized by bioinformatics, mutagenesis, genetic complementation, and functional protein expressions. Unlike enzymes involved in PCA biosynthesis, EsmA1 and EsmA2 together decisively promoted the PDC yield. The resulting PDC underwent a series of conversions to give 6-acetylphenazine-1-carboxylic acid, saphenic acid, and saphenamycin through a unique one-carbon extension by EsmB1-B5, a keto reduction by EsmC, and an esterification by EsmD1-D3, the atypical polyketide sythases, respectively. Two transcriptional regulators, EsmT1 and EsmT2, are required for esmeraldin production.
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Affiliation(s)
- Zhe Rui
- Department of Biological Science, Louisiana State University, Baton Rouge, LA 70803, USA
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11
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Mavrodi DV, Parejko JA, Mavrodi OV, Kwak YS, Weller DM, Blankenfeldt W, Thomashow LS. Recent insights into the diversity, frequency and ecological roles of phenazines in fluorescent Pseudomonas spp. Environ Microbiol 2012; 15:675-86. [PMID: 22882648 DOI: 10.1111/j.1462-2920.2012.02846.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phenazine compounds represent a large class of bacterial metabolites that are produced by some fluorescent Pseudomonas spp. and a few other bacterial genera. Phenazines were first noted in the scientific literature over 100 years ago, but for a long time were considered to be pigments of uncertain function. Following evidence that phenazines act as virulence factors in the opportunistic human and animal pathogen Pseudomonas aeruginosa and are actively involved in the suppression of plant pathogens, interest in these compounds has broadened to include investigations of their genetics, biosynthesis, activity as electron shuttles, and contribution to the ecology and physiology of the cells that produce them. This minireview highlights some recent and exciting insights into the diversity, frequency and ecological roles of phenazines produced by fluorescent Pseudomonas spp.
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Affiliation(s)
- Dmitri V Mavrodi
- Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USA.
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12
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Yu S, Vit A, Devenish S, Mahanty HK, Itzen A, Goody RS, Blankenfeldt W. Atomic resolution structure of EhpR: phenazine resistance in Enterobacter agglomerans Eh1087 follows principles of bleomycin/mitomycin C resistance in other bacteria. BMC STRUCTURAL BIOLOGY 2011; 11:33. [PMID: 21849072 PMCID: PMC3175449 DOI: 10.1186/1472-6807-11-33] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 08/17/2011] [Indexed: 11/10/2022]
Abstract
BACKGROUND The phenazines are redox-active secondary metabolites that a large number of bacterial strains produce and excrete into the environment. They possess antibiotic activity owing to the fact that they can reduce molecular oxygen to toxic reactive oxygen species. In order to take advantage of this activity, phenazine producers need to protect themselves against phenazine toxicity. Whereas it is believed that phenazine-producing pseudomonads possess highly active superoxide dismutases and catalases, it has recently been found that the plant-colonizing bacterium Enterobacter agglomerans expresses a small gene ehpR to render itself resistant towards D-alanyl-griseoluteic acid, the phenazine antibiotic produced by this strain. RESULTS To understand the resistance mechanism installed by EhpR we have determined its crystal structure in the apo form at 2.15 Å resolution and in complex with griseoluteic acid at 1.01 Å, respectively. While EhpR shares a common fold with glyoxalase-I/bleomycin resistance proteins, the ligand binding site does not contain residues that some related proteins employ to chemically alter their substrates. Binding of the antibiotic is mediated by π-stacking interactions of the aromatic moiety with the side chains of aromatic amino acids and by a few polar interactions. The dissociation constant KD between EhpR and griseoluteic acid was quantified as 244 ± 45 μM by microscale thermophoresis measurements. CONCLUSIONS The data accumulated here suggest that EhpR confers resistance by binding D-alanyl-griseoluteic acid and acting as a chaperone involved in exporting the antibiotic rather than by altering it chemically. It is tempting to speculate that EhpR acts in concert with EhpJ, a transport protein of the major facilitator superfamily that is also encoded in the phenazine biosynthesis operon of E. agglomerans. The low affinity of EhpR for griseoluteic acid may be required for its physiological function.
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Affiliation(s)
- Shen Yu
- Department of Physical Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
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