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Kučera I, Sedláček V. Flavin-dependent enzymatic and photochemical interconversions between phenylarsonic and phenylarsonous acids. Biometals 2025; 38:903-915. [PMID: 40240666 DOI: 10.1007/s10534-025-00685-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2024] [Accepted: 04/04/2025] [Indexed: 04/18/2025]
Abstract
Phenylarsonic acid is the parent compound of a group of derivatives that occur as anthropogenic environmental contaminants in both less toxic As(V) and much more toxic As(III) redox states. To elucidate the mechanisms underlying their enzymatic redox conversions, the activities of two flavin reductases, ArsH and FerA, from the soil bacterium Paracoccus denitrificans were compared. The stopped-flow data demonstrated that PhAs(V) oxidized dihydroflavin mononucleotide bound to ArsH, but not to FerA. This result proves that ArsH has some substrate specificity for organoarsenic compounds. Under aerobic conditions, both enzymes accelerated the oxidation of PhAs(III) in a catalase-sensitive manner, indicating that hydrogen peroxide acts as an intermediate. H2O2 was shown to react with PhAs(III) in a bimolecular (1:1) irreversible reaction. When exposed to blue light, flavin alone mediated rapid oxidation of PhAs(III) by O2. Photooxidation by flavin acted in concert with chemical oxidation by transiently accumulating H2O2. The described processes may be relevant in the context of arsenic ecotoxicology and remediation.
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Affiliation(s)
- Igor Kučera
- Department of Biochemistry, Faculty of Science, Masaryk University, Kotlářská 267/2, 61137, Brno, Czech Republic.
| | - Vojtěch Sedláček
- Department of Biochemistry, Faculty of Science, Masaryk University, Kotlářská 267/2, 61137, Brno, Czech Republic
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2
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Flores ADR, Khosla C. Characterization of the Flavin-Dependent Monooxygenase Involved in the Biosynthesis of the Nocardiosis-Associated Polyketide†. Biochemistry 2024; 63:2868-2877. [PMID: 39433512 PMCID: PMC11872153 DOI: 10.1021/acs.biochem.4c00480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2024]
Abstract
Some species of the Nocardia genus harbor a highly conserved biosynthetic gene cluster designated as the NOCardiosis-Associated Polyketide (NOCAP) synthase that produces a unique glycolipid natural product. The NOCAP glycolipid is composed of a fully substituted benzaldehyde headgroup linked to a polyfunctional alkyl tail and an O-linked disaccharide composed of 3-α-epimycarose and 2-O-methyl-α-rhamnose. Incorporation of the disaccharide unit is preceded by a critical step involving hydroxylation by NocapM, a flavin monooxygenase. In this study, we employed biochemical, spectroscopic, and kinetic analyses to explore the substrate scope of NocapM. Our findings indicate that NocapM catalyzes hydroxylation of diverse aromatic substrates, although the observed coupling between NADPH oxidation and substrate hydroxylation varies widely from substrate to substrate. Our in-depth biochemical characterization of NocapM provides a solid foundation for future mechanistic studies of this enzyme as well as its utilization as a practical biocatalyst.
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Affiliation(s)
| | - Chaitan Khosla
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
- Sarafan ChEM-H, Stanford University, Stanford, California 94305, United States
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3
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Lyons NS, Johnson SB, Sobrado P. Methods for biochemical characterization of flavin-dependent N-monooxygenases involved in siderophore biosynthesis. Methods Enzymol 2024; 702:247-280. [PMID: 39155115 DOI: 10.1016/bs.mie.2024.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
Siderophores are essential molecules released by some bacteria and fungi in iron-limiting environments to sequester ferric iron, satisfying metabolic needs. Flavin-dependent N-hydroxylating monooxygenases (NMOs) catalyze the hydroxylation of nitrogen atoms to generate important siderophore functional groups such as hydroxamates. It has been demonstrated that the function of NMOs is essential for virulence, implicating these enzymes as potential drug targets. This chapter aims to serve as a resource for the characterization of NMO's enzymatic activities using several biochemical techniques. We describe assays that allow for the determination of steady-state kinetic parameters, detection of hydroxylated amine products, measurement of the rate-limiting step(s), and the application toward drug discovery efforts. While not exhaustive, this chapter will provide a foundation for the characterization of enzymes involved in siderophore biosynthesis, allowing for gaps in knowledge within the field to be addressed.
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Affiliation(s)
- Noah S Lyons
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States
| | - Sydney B Johnson
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States; Center for Drug Discovery, Virginia Tech, Blacksburg, VA, United States; Department of Chemistry, Missouri University of Science and Technology, Rolla, MO, United States.
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4
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Johnson SB, Valentino H, Sobrado P. Kinetic Characterization and Identification of Key Active Site Residues of the L-Aspartate N-Hydroxylase, CreE. Chembiochem 2024; 25:e202400350. [PMID: 38775737 DOI: 10.1002/cbic.202400350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/17/2024] [Indexed: 07/04/2024]
Abstract
CreE is a flavin-dependent monooxygenase (FMO) that catalyzes three sequential nitrogen oxidation reactions of L-aspartate to produce nitrosuccinate, contributing to the biosynthesis of the antimicrobial and antiproliferative nautral product, cremeomycin. This compound contains a highly reactive diazo functional group for which the reaction of CreE is essential to its formation. Nitro and diazo functional groups can serve as potent electrophiles, important in some challenging nucleophilic addition reactions. Formation of these reactive groups positions CreE as a promising candidate for biomedical and synthetic applications. Here, we present the catalytic mechanism of CreE and the identification of active site residues critical to binding L-aspartate, aiding in future enzyme engineering efforts. Steady-state analysis demonstrated that CreE is very specific for NADPH over NADH and performs a highly coupled reaction with L-aspartate. Analysis of the rapid-reaction kinetics showed that flavin reduction is very fast, along with the formation of the oxygenating species, the C4a-hydroperoxyflavin. The slowest step observed was the dehydration of the flavin. Structural analysis and site-directed mutagenesis implicated T65, R291, and R440 in the binding L-aspartate. The data presented describes the catalytic mechanism and the active site architecture of this unique FMO.
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Affiliation(s)
- Sydney B Johnson
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, 360 West Campus Drive, Blacksburg, VA, 24061, USA
| | - Hannah Valentino
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, 360 West Campus Drive, Blacksburg, VA, 24061, USA
| | - Pablo Sobrado
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, 360 West Campus Drive, Blacksburg, VA, 24061, USA
- Department of Chemistry, Missouri University of Science and Technology, Rolla, MO, 65409
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5
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Li W, Cheng Z, Zhao Z, Li H, Liu Y, Lu X, Zhao G, Du YL. Discovery of a Bacterial Hydrazine Transferase That Constructs the N-Aminolactam Pharmacophore in Albofungin Biosynthesis. J Am Chem Soc 2024; 146:13399-13405. [PMID: 38698691 DOI: 10.1021/jacs.4c02311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Structural motifs containing nitrogen-nitrogen (N-N) bonds are prevalent in a large number of clinical drugs and bioactive natural products. Hydrazine (N2H4) serves as a widely utilized building block for the preparation of these N-N-containing molecules in organic synthesis. Despite its common use in chemical processes, no enzyme has been identified to catalyze the incorporation of free hydrazine in natural product biosynthesis. Here, we report that a hydrazine transferase catalyzes the condensation of N2H4 and an aromatic polyketide pathway intermediate, leading to the formation of a rare N-aminolactam pharmacophore in the biosynthesis of broad-spectrum antibiotic albofungin. These results expand the current knowledge on the biosynthetic mechanism for natural products with N-N units and should facilitate future development of biocatalysts for the production of N-N-containing chemicals.
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Affiliation(s)
- Wei Li
- Department of Microbiology and Department of Pharmacy of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Ziyang Cheng
- Department of Microbiology and Department of Pharmacy of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Zhijie Zhao
- Department of Microbiology and Department of Pharmacy of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Hu Li
- Department of Microbiology and Department of Pharmacy of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Yu Liu
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xingyu Lu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Instrumentation and Service Center for Molecular Sciences, Westlake University, Hangzhou 310024, China
| | - Guiyun Zhao
- Department of Microbiology and Department of Pharmacy of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Yi-Ling Du
- Department of Microbiology and Department of Pharmacy of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
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6
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Johnson SB, Paasch K, Shepard S, Sobrado P. Kinetic characterization of a flavin-dependent monooxygenase from the insect food crop pest, Zonocerus variegatus. Arch Biochem Biophys 2024; 754:109949. [PMID: 38430968 DOI: 10.1016/j.abb.2024.109949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/13/2024] [Accepted: 02/28/2024] [Indexed: 03/05/2024]
Abstract
Zonocerus variegatus, or the painted grasshopper, is a food crop pest endemic in Western and Central Africa. Agricultural industries in these regions rely heavily on natural defense mechanisms to control the grasshopper population such as plant-secreted alkaloid compounds. In recent years, the Z. variegatus population has continued to rise due to acquired resistance to alkaloids. Here we focus on the kinetic characterization of a flavin-dependent monooxygenase, ZvFMO, that catalyzes the nitrogen oxidation of many of these alkaloid compounds and confers resistance to the insect. Expression and purification of ZvFMO through a traditional E. coli expression system was successful and provided a unique opportunity to characterize the catalytic properties of an FMO from insects. ZvFMO was found to catalyze oxidation reactions of tertiary nitrogen atoms and the sulfur of cysteamine. Using stopped-flow spectroscopy, we have determined the kinetic mechanism of ZvFMO. We assessed F383 for its involvement in substrate binding, which was previously proposed, and determined that this residue does not play a major role in binding substrates. Through molecular docking, we identified N304 and demonstrated that this residue plays a role in substrate binding. The role of K215 was studied and was shown that it plays a critical role in NAD(P)H binding and cofactor selectivity.
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Affiliation(s)
- Sydney B Johnson
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Kathryn Paasch
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Starlina Shepard
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061, USA; Center for Drug Discovery, Virginia Tech, Blacksburg, VA, 24061, USA.
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7
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Pierdominici‐Sottile G, Palma J, Ferrelli ML, Sobrado P. The dynamics of the flavin, NADPH, and active site loops determine the mechanism of activation of class B flavin-dependent monooxygenases. Protein Sci 2024; 33:e4935. [PMID: 38501462 PMCID: PMC10962481 DOI: 10.1002/pro.4935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 03/20/2024]
Abstract
Flavin-dependent monooxygenases (FMOs) constitute a diverse enzyme family that catalyzes crucial hydroxylation, epoxidation, and Baeyer-Villiger reactions across various metabolic pathways in all domains of life. Due to the intricate nature of this enzyme family's mechanisms, some aspects of their functioning remain unknown. Here, we present the results of molecular dynamics computations, supplemented by a bioinformatics analysis, that clarify the early stages of their catalytic cycle. We have elucidated the intricate binding mechanism of NADPH and L-Orn to a class B monooxygenase, the ornithine hydroxylase fromAspergillus $$ Aspergillus $$ fumigatus $$ fumigatus $$ known as SidA. Our investigation involved a comprehensive characterization of the conformational changes associated with the FAD (Flavin Adenine Dinucleotide) cofactor, transitioning from the out to the in position. Furthermore, we explored the rotational dynamics of the nicotinamide ring of NADPH, shedding light on its role in facilitating FAD reduction, supported by experimental evidence. Finally, we also analyzed the extent of conservation of two Tyr-loops that play critical roles in the process.
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Affiliation(s)
- Gustavo Pierdominici‐Sottile
- Departamento de Ciencia y TecnologíaUniversidad Nacional de QuilmesBernalArgentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)CABAArgentina
| | - Juliana Palma
- Departamento de Ciencia y TecnologíaUniversidad Nacional de QuilmesBernalArgentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)CABAArgentina
| | - María Leticia Ferrelli
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)CABAArgentina
- Instituto de Biotecnología y Biología Molecular (IBBM, UNLP‐CONICET), Facultad de Ciencias ExactasUniversidad Nacional de La PlataLa PlataBuenos AiresArgentina
| | - Pablo Sobrado
- Department of BiochemistryVirginia TechBlacksburgVirginiaUSA
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8
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Rotilio L, Boverio A, Nguyen QT, Mannucci B, Fraaije MW, Mattevi A. A biosynthetic aspartate N-hydroxylase performs successive oxidations by holding intermediates at a site away from the catalytic center. J Biol Chem 2023; 299:104904. [PMID: 37302552 PMCID: PMC10404684 DOI: 10.1016/j.jbc.2023.104904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/28/2023] [Accepted: 05/31/2023] [Indexed: 06/13/2023] Open
Abstract
Nitrosuccinate is a biosynthetic building block in many microbial pathways. The metabolite is produced by dedicated L-aspartate hydroxylases that use NADPH and molecular oxygen as co-substrates. Here, we investigate the mechanism underlying the unusual ability of these enzymes to perform successive rounds of oxidative modifications. The crystal structure of Streptomyces sp. V2 L-aspartate N-hydroxylase outlines a characteristic helical domain wedged between two dinucleotide-binding domains. Together with NADPH and FAD, a cluster of conserved arginine residues forms the catalytic core at the domain interface. Aspartate is found to bind in an entry chamber that is close to but not in direct contact with the flavin. It is recognized by an extensive H-bond network that explains the enzyme's strict substrate-selectivity. A mutant designed to create steric and electrostatic hindrance to substrate binding disables hydroxylation without perturbing the NADPH oxidase side-activity. Critically, the distance between the FAD and the substrate is far too long to afford N-hydroxylation by the C4a-hydroperoxyflavin intermediate whose formation is confirmed by our work. We conclude that the enzyme functions through a catch-and-release mechanism. L-aspartate slides into the catalytic center only when the hydroxylating apparatus is formed. It is then re-captured by the entry chamber where it waits for the next round of hydroxylation. By iterating these steps, the enzyme minimizes the leakage of incompletely oxygenated products and ensures that the reaction carries on until nitrosuccinate is formed. This unstable product can then be engaged by a successive biosynthetic enzyme or undergoes spontaneous decarboxylation to produce 3-nitropropionate, a mycotoxin.
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Affiliation(s)
- Laura Rotilio
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Alessandro Boverio
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy; Molecular Enzymology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Quoc-Thai Nguyen
- Faculty of Pharmacy, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam
| | | | - Marco W Fraaije
- Molecular Enzymology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Andrea Mattevi
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy.
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Kim W, Kim M, Park W. Unlocking the mystery of lysine toxicity on Microcystis aeruginosa. JOURNAL OF HAZARDOUS MATERIALS 2023; 448:130932. [PMID: 36860069 DOI: 10.1016/j.jhazmat.2023.130932] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 01/19/2023] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
Lysine toxicity on certain groups of bacterial cells has been recognized for many years, but the detailed molecular mechanisms that drive this phenomenon have not been elucidated. Many cyanobacteria including Microcystis aeruginosa cannot efficiently export and degrade lysine, although they have evolved to maintain a single copy of the lysine uptake system through which arginine or ornithine can also be transported into the cytoplasm. Autoradiographic analysis using 14C-l-lysine confirmed that lysine was competitively uptaken into cells with arginine or ornithine, which explained the arginine or ornithine-mediated alleviation of lysine toxicity in M. aeruginosa. A relatively non-specific MurE amino acid ligase could incorporate l-lysine into the 3rd position of UDP-N-acetylmuramyl-tripeptide by replacing meso-diaminopimelic acid during the stepwise addition of amino acids on peptidoglycan (PG) biosynthesis. However, further transpeptidation was blocked because lysine substitution at the pentapeptide of the cell wall inhibited the activity of transpeptidases. The leaky PG structure caused irreversible damage to the photosynthetic system and membrane integrity. Collectively, our results suggest that a lysine-mediated coarse-grained PG network and the absence of concrete septal PG lead to the death of slow-growing cyanobacteria.
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Affiliation(s)
- Wonjae Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Minkyung Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
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10
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Lyons NS, Bogner AN, Tanner JJ, Sobrado P. Kinetic and Structural Characterization of a Flavin-Dependent Putrescine N-Hydroxylase from Acinetobacter baumannii. Biochemistry 2022; 61:2607-2620. [DOI: 10.1021/acs.biochem.2c00493] [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]
Affiliation(s)
- Noah S. Lyons
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Alexandra N. Bogner
- Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - John J. Tanner
- Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Pablo Sobrado
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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11
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Yang J, Wencewicz TA. In Vitro Reconstitution of Fimsbactin Biosynthesis from Acinetobacter baumannii. ACS Chem Biol 2022; 17:2923-2935. [PMID: 36122366 DOI: 10.1021/acschembio.2c00573] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Siderophores produced via nonribosomal peptide synthetase (NRPS) pathways serve as critical virulence factors for many pathogenic bacteria. Improved knowledge of siderophore biosynthesis guides the development of inhibitors, vaccines, and other therapeutic strategies. Fimsbactin A is a mixed ligand siderophore derived from human pathogenic Acinetobacter baumannii that contains phenolate-oxazoline, catechol, and hydroxamate metal chelating groups branching from a central l-Ser tetrahedral unit via amide and ester linkages. Fimsbactin A is derived from two molecules of l-Ser, two molecules of 2,3-dihydroxybenzoic acid (DHB), and one molecule of l-Orn and is a product of the fbs biosynthetic operon. Here, we report the complete in vitro reconstitution of fimsbactin A biosynthesis in a cell-free system using purified enzymes. We demonstrate the conversion of l-Orn to N1-acetyl-N1-hydroxy-putrescine (ahPutr) via ordered action of FbsJ (decarboxylase), FbsI (flavin N-monooxygenase), and FbsK (N-acetyltransferase). We achieve conversion of l-Ser, DHB, and l-Orn to fimsbactin A using FbsIJK in combination with the NRPS modules FbsEFGH. We also demonstrate chemoenzymatic conversion of synthetic ahPutr to fimsbactin A using FbsEFGH and establish the substrate selectivity for the NRPS adenylation domains in FbsH (DHB) and FbsF (l-Ser). We assign a role for the type II thioesterase FbsM in producing the shunt metabolite 2-(2,3-dihydroxyphenyl)-4,5-dihydrooxazole-4-carboxylic acid (DHB-oxa) via cleavage of the corresponding thioester intermediate that is tethered to NRPS peptidyl carrier domains during biosynthetic assembly. We propose a mechanism for branching NRPS-derived peptides via amide and ester linkages via the dynamic equilibration of N-DHB-Ser and O-DHB-Ser thioester intermediates via hydrolysis of DHB-oxa thioester intermediates. We also propose a genetic signature for NRPS "branching" in the presence of a terminating C-T-C motif (FbsG).
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Affiliation(s)
- Jinping Yang
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
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12
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Valentino H, Sobrado P. Characterization of a Nitro-Forming Enzyme Involved in Fosfazinomycin Biosynthesis. Biochemistry 2021; 60:2851-2864. [PMID: 34516102 DOI: 10.1021/acs.biochem.1c00512] [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
N-hydroxylating monooxygenases (NMOs) are a subclass of flavin-dependent enzymes that hydroxylate nitrogen atoms. Recently, unique NMOs that perform multiple reactions on one substrate molecule have been identified. Fosfazinomycin M (FzmM) is one such NMO, forming nitrosuccinate from aspartate (Asp) in the fosfazinomycin biosynthetic pathway in some Streptomyces sp. This work details the biochemical and kinetic analysis of FzmM. Steady-state kinetic investigation shows that FzmM performs a coupled reaction with Asp (kcat, 3.0 ± 0.01 s-1) forming nitrosuccinate, which can be converted to fumarate and nitrite by the action of FzmL. FzmM displays a 70-fold higher kcat/KM value for NADPH compared to NADH and has a narrow optimal pH range (7.5-8.0). Contrary to other NMOs where the kred is rate-limiting, FzmM exhibits a very fast kred (50 ± 0.01 s-1 at 4 °C) with NADPH. NADPH binds at a KD value of ∼400 μM, and hydride transfer occurs with pro-R stereochemistry. Oxidation of FzmM in the absence of Asp exhibits a spectrum with a shoulder at ∼370 nm, consistent with the formation of a C(4a)-hydroperoxyflavin intermediate, which decays into oxidized flavin and hydrogen peroxide at a rate 100-fold slower than the kcat. This reaction is enhanced in the presence of Asp with a slightly faster kox than the kcat, suggesting that flavin dehydration or Asp oxidation is partially rate limiting. Multiple sequence analyses of FzmM to NMOs identified conserved residues involved in flavin binding but not for NADPH. Additional sequence analysis to related monooxygenases suggests that FzmM shares sequence motifs absent in other NMOs.
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Affiliation(s)
- Hannah Valentino
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.,Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.,Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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13
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Giddings LA, Lountos GT, Kim KW, Brockley M, Needle D, Cherry S, Tropea JE, Waugh DS. Characterization of a broadly specific cadaverine N-hydroxylase involved in desferrioxamine B biosynthesis in Streptomyces sviceus. PLoS One 2021; 16:e0248385. [PMID: 33784308 PMCID: PMC8009421 DOI: 10.1371/journal.pone.0248385] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/26/2021] [Indexed: 02/07/2023] Open
Abstract
N-hydroxylating flavin-dependent monooxygenases (FMOs) are involved in the biosynthesis of hydroxamate siderophores, playing a key role in microbial virulence. Herein, we report the first structural and kinetic characterization of a novel alkyl diamine N-hydroxylase DesB from Streptomyces sviceus (SsDesB). This enzyme catalyzes the first committed step in the biosynthesis of desferrioxamine B, a clinical drug used to treat iron overload disorders. X-ray crystal structures of the SsDesB holoenzyme with FAD and the ternary complex with bound NADP+ were solved at 2.86 Å and 2.37 Å resolution, respectively, providing a structural view of the active site environment. SsDesB crystallized as a tetramer and the structure of the individual protomers closely resembles the structures of homologous N-hydroxylating FMOs from Erwinia amylovora (DfoA), Pseudomonas aeruginosa (PvdA), and Aspergillus fumigatus (SidA). Using NADPH oxidation, oxygen consumption, and product formation assays, kinetic parameters were determined for various substrates with SsDesB. SsDesB exhibited typical saturation kinetics with substrate inhibition at high concentrations of NAD(P)H as well as cadaverine. The apparent kcat values for NADPH in steady-state NADPH oxidation and oxygen consumption assays were 0.28 ± 0.01 s-1 and 0.24 ± 0.01 s-1, respectively. However, in product formation assays used to measure the rate of N-hydroxylation, the apparent kcat for NADPH (0.034 ± 0.008 s-1) was almost 10-fold lower under saturating FAD and cadaverine concentrations, reflecting an uncoupled reaction, and the apparent NADPH KM was 33 ± 24 μM. Under saturating FAD and NADPH concentrations, the apparent kcat and KM for cadaverine in Csaky assays were 0.048 ± 0.004 s-1 and 19 ± 9 μM, respectively. SsDesB also N-hydroxylated putrescine, spermidine, and L-lysine substrates but not alkyl (di)amines that were branched or had fewer than four methylene units in an alkyl chain. These data demonstrate that SsDesB has wider substrate scope compared to other well-studied ornithine and lysine N-hydroxylases, making it an amenable biocatalyst for the production of desferrioxamine B, derivatives, and other N-substituted products.
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Affiliation(s)
- Lesley-Ann Giddings
- Department of Chemistry, Smith College, Northampton, MA, United States of America
- Department of Chemistry & Biochemistry, Middlebury College, Middlebury, VT, United States of America
| | - George T. Lountos
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD, United States of America
| | - Kang Woo Kim
- Department of Chemistry & Biochemistry, Middlebury College, Middlebury, VT, United States of America
| | - Matthew Brockley
- Department of Chemistry & Biochemistry, Middlebury College, Middlebury, VT, United States of America
| | - Danielle Needle
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
| | - Scott Cherry
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
| | - Joseph E. Tropea
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
| | - David S. Waugh
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
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14
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Nóbile ML, Stricker AM, Marchesano L, Iribarren AM, Lewkowicz ES. N-oxygenation of amino compounds: Early stages in its application to the biocatalyzed preparation of bioactive compounds. Biotechnol Adv 2021; 51:107726. [PMID: 33675955 DOI: 10.1016/j.biotechadv.2021.107726] [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: 11/16/2020] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 10/22/2022]
Abstract
Among the compounds that contain unusual functional groups, nitro is perhaps one of the most interesting due to the valuable properties it confers on pharmaceuticals and explosives. Traditional chemistry has for many years used environmentally unfriendly strategies; in contrast, the biocatalyzed production of this type of products offers a promising alternative. The small family of enzymes formed by N-oxygenases allows the conversion of an amino group to a nitro through the sequential addition of oxygen. These enzymes also make it possible to obtain other less oxidized N-O functions, such as hydroxylamine or nitroso, present in intermediate or final products. The current substrates on which these enzymes are reported to work encompass a few aromatic molecules and sugars. The unique characteristics of N-oxygenases and the great economic value of the products that they could generate, place them in a position of very high scientific and industrial interest. The most important and best studied N-oxygenases will be presented here.
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Affiliation(s)
- Matías L Nóbile
- Universidad Nacional de Quilmes, CONICET, Departamento de Ciencia y Tecnología, Biocatalysis and Biotransformation Laboratory, Roque Sáenz Peña 352, Bernal 1876, Buenos Aires, Argentina.
| | - Abigail M Stricker
- Universidad Nacional de Quilmes, CONICET, Departamento de Ciencia y Tecnología, Biocatalysis and Biotransformation Laboratory, Roque Sáenz Peña 352, Bernal 1876, Buenos Aires, Argentina
| | - Lucas Marchesano
- Universidad Nacional de Quilmes, CONICET, Departamento de Ciencia y Tecnología, Biocatalysis and Biotransformation Laboratory, Roque Sáenz Peña 352, Bernal 1876, Buenos Aires, Argentina
| | - Adolfo M Iribarren
- Universidad Nacional de Quilmes, CONICET, Departamento de Ciencia y Tecnología, Biocatalysis and Biotransformation Laboratory, Roque Sáenz Peña 352, Bernal 1876, Buenos Aires, Argentina
| | - Elizabeth S Lewkowicz
- Universidad Nacional de Quilmes, CONICET, Departamento de Ciencia y Tecnología, Biocatalysis and Biotransformation Laboratory, Roque Sáenz Peña 352, Bernal 1876, Buenos Aires, Argentina
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15
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Reis RAG, Li H, Johnson M, Sobrado P. New frontiers in flavin-dependent monooxygenases. Arch Biochem Biophys 2021; 699:108765. [PMID: 33460580 DOI: 10.1016/j.abb.2021.108765] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 12/15/2022]
Abstract
Flavin-dependent monooxygenases catalyze a wide variety of redox reactions in important biological processes and are responsible for the synthesis of highly complex natural products. Although much has been learned about FMO chemistry in the last ~80 years of research, several aspects of the reactions catalyzed by these enzymes remain unknown. In this review, we summarize recent advancements in the flavin-dependent monooxygenase field including aspects of flavin dynamics, formation and stabilization of reactive species, and the hydroxylation mechanism. Novel catalysis of flavin-dependent N-oxidases involving consecutive oxidations of amines to generate oximes or nitrones is presented and the biological relevance of the products is discussed. In addition, the activity of some FMOs have been shown to be essential for the virulence of several human pathogens. We also discuss the biomedical relevance of FMOs in antibiotic resistance and the efforts to identify inhibitors against some members of this important and growing family enzymes.
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Affiliation(s)
| | - Hao Li
- Department of Biochemistry, Blacksburg, VA, 24061, USA
| | - Maxim Johnson
- Department of Biochemistry, Blacksburg, VA, 24061, USA
| | - Pablo Sobrado
- Department of Biochemistry, Blacksburg, VA, 24061, USA; Center for Drug Discovery, Virginia Tech, Blacksburg, VA, 24061, USA.
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16
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Hofmann M, Martin del Campo JS, Sobrado P, Tischler D. Biosynthesis of desferrioxamine siderophores initiated by decarboxylases: A functional investigation of two lysine/ornithine-decarboxylases from Gordonia rubripertincta CWB2 and Pimelobacter simplex 3E. Arch Biochem Biophys 2020; 689:108429. [DOI: 10.1016/j.abb.2020.108429] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 12/14/2022]
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17
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Mügge C, Heine T, Baraibar AG, van Berkel WJH, Paul CE, Tischler D. Flavin-dependent N-hydroxylating enzymes: distribution and application. Appl Microbiol Biotechnol 2020; 104:6481-6499. [PMID: 32504128 PMCID: PMC7347517 DOI: 10.1007/s00253-020-10705-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/18/2020] [Accepted: 05/24/2020] [Indexed: 02/06/2023]
Abstract
Amino groups derived from naturally abundant amino acids or (di)amines can be used as "shuttles" in nature for oxygen transfer to provide intermediates or products comprising N-O functional groups such as N-hydroxy, oxazine, isoxazolidine, nitro, nitrone, oxime, C-, S-, or N-nitroso, and azoxy units. To this end, molecular oxygen is activated by flavin, heme, or metal cofactor-containing enzymes and transferred to initially obtain N-hydroxy compounds, which can be further functionalized. In this review, we focus on flavin-dependent N-hydroxylating enzymes, which play a major role in the production of secondary metabolites, such as siderophores or antimicrobial agents. Flavoprotein monooxygenases of higher organisms (among others, in humans) can interact with nitrogen-bearing secondary metabolites or are relevant with respect to detoxification metabolism and are thus of importance to understand potential medical applications. Many enzymes that catalyze N-hydroxylation reactions have specific substrate scopes and others are rather relaxed. The subsequent conversion towards various N-O or N-N comprising molecules is also described. Overall, flavin-dependent N-hydroxylating enzymes can accept amines, diamines, amino acids, amino sugars, and amino aromatic compounds and thus provide access to versatile families of compounds containing the N-O motif. Natural roles as well as synthetic applications are highlighted. Key points • N-O and N-N comprising natural and (semi)synthetic products are highlighted. • Flavin-based NMOs with respect to mechanism, structure, and phylogeny are reviewed. • Applications in natural product formation and synthetic approaches are provided. Graphical abstract .
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Affiliation(s)
- Carolin Mügge
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Thomas Heine
- Environmental Microbiology, Faculty of Chemistry and Physics, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
| | - Alvaro Gomez Baraibar
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany
- Rottendorf Pharma GmbH, Ostenfelder Str. 51-61, 59320, Ennigerloh, Germany
| | - Willem J H van Berkel
- Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen, The Netherlands
| | - Caroline E Paul
- Biocatalysis, Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, HZ 2629, Delft, The Netherlands
| | - Dirk Tischler
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
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18
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Valentino H, Campbell AC, Schuermann JP, Sultana N, Nam HG, LeBlanc S, Tanner JJ, Sobrado P. Structure and function of a flavin-dependent S-monooxygenase from garlic ( Allium sativum). J Biol Chem 2020; 295:11042-11055. [PMID: 32527723 DOI: 10.1074/jbc.ra120.014484] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/07/2020] [Indexed: 12/26/2022] Open
Abstract
Allicin is a component of the characteristic smell and flavor of garlic (Allium sativum). A flavin-containing monooxygenase (FMO) produced by A. sativum (AsFMO) was previously proposed to oxidize S-allyl-l-cysteine (SAC) to alliin, an allicin precursor. Here, we present a kinetic and structural characterization of AsFMO that suggests a possible contradiction to this proposal. Results of steady-state kinetic analyses revealed that AsFMO exhibited negligible activity with SAC; however, the enzyme was highly active with l-cysteine, N-acetyl-l-cysteine, and allyl mercaptan. We found that allyl mercaptan with NADPH was the preferred substrate-cofactor combination. Rapid-reaction kinetic analyses showed that NADPH binds tightly (KD of ∼2 μm) to AsFMO and that the hydride transfer occurs with pro-R stereospecificity. We detected the formation of a long-wavelength band when AsFMO was reduced by NADPH, probably representing the formation of a charge-transfer complex. In the absence of substrate, the reduced enzyme, in complex with NADP+, reacted with oxygen and formed an intermediate with a spectrum characteristic of C4a-hydroperoxyflavin, which decays several orders of magnitude more slowly than the k cat The presence of substrate enhanced C4a-hydroperoxyflavin formation and, upon hydroxylation, oxidation occurred with a rate constant similar to the k cat The structure of AsFMO complexed with FAD at 2.08-Å resolution features two domains for binding of FAD and NADPH, representative of class B flavin monooxygenases. These biochemical and structural results are consistent with AsFMO being an S-monooxygenase involved in allicin biosynthesis through direct formation of sulfenic acid and not SAC oxidation.
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Affiliation(s)
- Hannah Valentino
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA.,Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, USA
| | - Ashley C Campbell
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Jonathan P Schuermann
- Northeastern Collaborative Access Team, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
| | - Nazneen Sultana
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Han G Nam
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Sophie LeBlanc
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - John J Tanner
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA .,Department of Chemistry, University of Missouri, Columbia, Missouri, USA
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA .,Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, USA
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19
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Comparative Investigation into Formycin A and Pyrazofurin A Biosynthesis Reveals Branch Pathways for the Construction of C-Nucleoside Scaffolds. Appl Environ Microbiol 2020; 86:AEM.01971-19. [PMID: 31676476 DOI: 10.1128/aem.01971-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 10/25/2019] [Indexed: 12/23/2022] Open
Abstract
Formycin A (FOR-A) and pyrazofurin A (PRF-A) are purine-related C-nucleoside antibiotics in which ribose and a pyrazole-derived base are linked by a C-glycosidic bond. However, the logic underlying the biosynthesis of these molecules has remained largely unexplored. Here, we report the discovery of the pathways for FOR-A and PRF-A biosynthesis from diverse actinobacteria and propose that their biosynthesis is likely initiated by a lysine N 6-monooxygenase. Moreover, we show that forT and prfT (involved in FOR-A and PRF-A biosynthesis, respectively) mutants are correspondingly capable of accumulating the unexpected pyrazole-related intermediates 4-amino-3,5-dicarboxypyrazole and 3,5-dicarboxy-4-oxo-4,5-dihydropyrazole. We also decipher the enzymatic mechanism of ForT/PrfT for C-glycosidic bond formation in FOR-A/PRF-A biosynthesis. To our knowledge, ForT/PrfT represents an example of β-RFA-P (β-ribofuranosyl-aminobenzene 5'-phosphate) synthase-like enzymes governing C-nucleoside scaffold construction in natural product biosynthesis. These data establish a foundation for combinatorial biosynthesis of related purine nucleoside antibiotics and also open the way for target-directed genome mining of PRF-A/FOR-A-related antibiotics.IMPORTANCE FOR-A and PRF-A are C-nucleoside antibiotics known for their unusual chemical structures and remarkable biological activities. Deciphering the enzymatic mechanism for the construction of a C-nucleoside scaffold during FOR-A/PRF-A biosynthesis will not only expand the biochemical repertoire for novel enzymatic reactions but also permit target-oriented genome mining of FOR-A/PRF-A-related C-nucleoside antibiotics. Moreover, the availability of FOR-A/PRF-A biosynthetic gene clusters will pave the way for the rational generation of designer FOR-A/PRF-A derivatives with enhanced/selective bioactivity via synthetic biology strategies.
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20
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Fürst MJLJ, Fiorentini F, Fraaije MW. Beyond active site residues: overall structural dynamics control catalysis in flavin-containing and heme-containing monooxygenases. Curr Opin Struct Biol 2019; 59:29-37. [DOI: 10.1016/j.sbi.2019.01.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 01/25/2019] [Indexed: 12/31/2022]
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21
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Saroja NR, Mohan AHS, Srividya D, Supreetha K. Chaperone-assisted expression and purification of putrescine monooxygenase from Shewanella putrefaciens-95. Protein Expr Purif 2019; 157:9-16. [PMID: 30654014 DOI: 10.1016/j.pep.2019.01.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 01/09/2019] [Accepted: 01/09/2019] [Indexed: 01/22/2023]
Abstract
A putrescine monooxygenase from Shewanella putrefaciens 95 (SpPMO) is the initial enzyme catalyzing the hydroxylation of putrescine to N-hydroxyl putrescine, the precursor for the synthesis of a siderophore putrebactin was identified. This PMO clustered together with known characterized NMOs from Shewanella baltica, Bordetella pertussis, Erwinia amylovora, Streptomyces sp. Gordonia rubripertincta, Pseudomonas aeruginosa and outgrouped from Escherichia coli, Nocardia farcinica, and Rhodococcus erythropolis. The deduced SpPMO protein showed 53% and 36% sequence identity with other characterized bacterial NMOs from Erwinia amylovora and Gordonia rubripertincta respectively. In this investigation, we have cloned the complete 1518bp coding sequence of pubA from Shewanella putrefaciens 95 encoding the corresponding protein SpPMO. It comprises 505 amino acid residues in length and has approximately a molecular weight of 54 kDa. Chaperone-assisted heterologous expression of SpPMO in pET151Topo expression vector under the control of bacteriophage T7 promoter permitted a stringent IPTG dependent expression. It has been successfully cloned, overexpressed and purified as a soluble His6 -tagged enzyme using E. coli as a cloning and expression host. The expression of recombinant SpPMO was confirmed by Western blotting using anti-His6 antibody. The purified protein showed FAD and NADPH dependent N-hydroxylation activity. This study has paved a way to understand the hydroxylation step of putrebactin synthesis which can be further investigated by studying its kinetic mechanism and physiological role.
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Affiliation(s)
- Narsing Rao Saroja
- Pesticide Residue and Food Quality Analysis Laboratory, University of Agricultural Sciences, Raichur, 584104, Karnataka, India.
| | - Anil H Shyam Mohan
- Department of Biotechnology, Dayananda Sagar College of Engineering, Kumaraswamy Layout, Shavige Malleswara Hills, Bengaluru, 78, Karnataka, India
| | - D Srividya
- Pesticide Residue and Food Quality Analysis Laboratory, University of Agricultural Sciences, Raichur, 584104, Karnataka, India
| | - K Supreetha
- Department of Biotechnology, Dayananda Sagar College of Engineering, Kumaraswamy Layout, Shavige Malleswara Hills, Bengaluru, 78, Karnataka, India
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22
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Fürst MJLJ, Romero E, Gómez Castellanos JR, Fraaije MW, Mattevi A. Side-Chain Pruning Has Limited Impact on Substrate Preference in a Promiscuous Enzyme. ACS Catal 2018; 8:11648-11656. [PMID: 30687578 PMCID: PMC6345240 DOI: 10.1021/acscatal.8b03793] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/26/2018] [Indexed: 01/02/2023]
Abstract
![]()
Detoxifying
enzymes such as flavin-containing monooxygenases deal
with a huge array of highly diverse xenobiotics and toxic compounds.
In addition to being of high physiological relevance, these drug-metabolizing
enzymes are useful catalysts for synthetic chemistry. Despite the
wealth of studies, the molecular basis of their relaxed substrate
selectivity remains an open question. Here, we addressed this issue
by applying a cumulative alanine mutagenesis approach to cyclohexanone
monooxygenase from Thermocrispum municipale, a flavin-dependent
Baeyer–Villiger monooxygenase which we chose as a model system
because of its pronounced thermostability and substrate promiscuity.
Simultaneous removal of up to eight noncatalytic active-site side
chains including four phenylalanines had no effect on protein folding,
thermostability, and cofactor loading. We observed a linear decrease
in activity, rather than a selectivity switch, and attributed this
to a less efficient catalytic environment in the enlarged active-site
space. Time-resolved kinetic studies confirmed this interpretation.
We also determined the crystal structure of the enzyme in complex
with a mimic of the reaction intermediate that shows an unaltered
overall protein conformation. These findings led us to propose that
this cyclohexanone monooxygenase may lack a distinct substrate selection
mechanism altogether. We speculate that the main or exclusive function
of the protein shell in promiscuous enzymes might be the stabilization
and accessibility of their very reactive catalytic intermediates.
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Affiliation(s)
- Maximilian J. L. J. Fürst
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Elvira Romero
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | | | - Marco W. Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Andrea Mattevi
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 1, 27100, Pavia, Italy
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23
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Hartmann M, Zeier J. l-lysine metabolism to N-hydroxypipecolic acid: an integral immune-activating pathway in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:5-21. [PMID: 30035374 DOI: 10.1111/tpj.14037] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 06/22/2018] [Accepted: 07/03/2018] [Indexed: 05/03/2023]
Abstract
l-lysine catabolic routes in plants include the saccharopine pathway to α-aminoadipate and decarboxylation of lysine to cadaverine. The current review will cover a third l-lysine metabolic pathway having a major role in plant systemic acquired resistance (SAR) to pathogen infection that was recently discovered in Arabidopsis thaliana. In this pathway, the aminotransferase AGD2-like defense response protein (ALD1) α-transaminates l-lysine and generates cyclic dehydropipecolic (DP) intermediates that are subsequently reduced to pipecolic acid (Pip) by the reductase SAR-deficient 4 (SARD4). l-pipecolic acid, which occurs ubiquitously in the plant kingdom, is further N-hydroxylated to the systemic acquired resistance (SAR)-activating metabolite N-hydroxypipecolic acid (NHP) by flavin-dependent monooxygenase1 (FMO1). N-hydroxypipecolic acid induces the expression of a set of major plant immune genes to enhance defense readiness, amplifies resistance responses, acts synergistically with the defense hormone salicylic acid, promotes the hypersensitive cell death response and primes plants for effective immune mobilization in cases of future pathogen challenge. This pathogen-inducible NHP biosynthetic pathway is activated at the transcriptional level and involves feedback amplification. Apart from FMO1, some cytochrome P450 monooxygenases involved in secondary metabolism catalyze N-hydroxylation reactions in plants. In specific taxa, pipecolic acid might also serve as a precursor in the biosynthesis of specialized natural products, leading to C-hydroxylated and otherwise modified piperidine derivatives, including indolizidine alkaloids. Finally, we show that NHP is glycosylated in Arabidopsis to form a hexose-conjugate, and then discuss open questions in Pip/NHP-related research.
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Affiliation(s)
- Michael Hartmann
- Department of Biology, Institute for Molecular Ecophysiology of Plants, Heinrich Heine University, Universitätsstraße 1, D-40225, Düsseldorf, Germany
| | - Jürgen Zeier
- Department of Biology, Institute for Molecular Ecophysiology of Plants, Heinrich Heine University, Universitätsstraße 1, D-40225, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Universitätsstraße 1, D-40225, Düsseldorf, Germany
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24
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Fordwour OB, Wolthers KR. Active site arginine controls the stereochemistry of hydride transfer in cyclohexanone monooxygenase. Arch Biochem Biophys 2018; 659:47-56. [PMID: 30287236 DOI: 10.1016/j.abb.2018.09.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/26/2018] [Accepted: 09/28/2018] [Indexed: 12/01/2022]
Abstract
Cyclohexanone monooxygenase (CHMO) uses NADPH and O2 to insert oxygen into an array of (a)cyclic ketones to form esters or lactones. Herein, the role of two conserved active site residues (R327 and D57) in controlling the binding mode of NADP(H) was investigated. Wild type CHMO elicits a kinetic isotope effect (KIE) of 4.7 ± 0.1 and 1.1 ± 0.1 with 4(R)-[4-2H]NADPH and 4(S)-[4-2H]NADPH, respectively, consistent with transfer of the proR hydrogen to FAD. Strikingly, the R327K variant appears to lack stereospecificity for hydride transfer as a KIE of 1.5 ± 0.1 and 2.5 ± 0.1 was observed for the proR and proS deuterated forms of NADPH. 1H NMR of the NADP+ products confirmed that the R327K variant abstracts either the proR or proS hydrogen from NADPH. While the D57A variant retained stereospecificity for the proR hydrogen, this substitution resulted in slow decomposition of the C4a-peroxyflavin intermediate in the presence of cyclohexanone. Based on published structures of a related flavin monooxygenase, we suggest that elimination of the hydrogen bond between D57 and R327 in the D57A variant causes R327 to adopt a substrate-induced conformation that slows substrate access to the active site, thereby prolonging the lifetime of the C4a-peroxyflavin intermediate.
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Affiliation(s)
- Osei Boakye Fordwour
- Department of Chemistry, University of British Columbia, Okanagan Campus, 3247 University Way, Kelowna, BC, V1V 1V7, Canada
| | - Kirsten R Wolthers
- Department of Chemistry, University of British Columbia, Okanagan Campus, 3247 University Way, Kelowna, BC, V1V 1V7, Canada.
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25
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Robinson RM, Klancher CA, Rodriguez PJ, Sobrado P. Flavin oxidation in flavin-dependent N-monooxygenases. Protein Sci 2018; 28:90-99. [PMID: 30098072 DOI: 10.1002/pro.3487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 07/14/2018] [Accepted: 07/23/2018] [Indexed: 01/08/2023]
Abstract
Siderophore A (SidA) from Aspergillus fumigatus is a flavin-containing monooxygenase that hydroxylates ornithine (Orn) at the amino group of the side chain. Lysine (Lys) also binds to the active site of SidA; however, hydroxylation is not efficient and H2 O2 is the main product. The effect of pH on steady-state kinetic parameters was measured and the results were consistent with Orn binding with the side chain amino group in the neutral form. From the pH dependence on flavin oxidation in the absence of Orn, a pKa value >9 was determined and assigned to the FAD-N5 atom. In the presence of Orn, the pH dependence displayed a pKa value of 6.7 ±0.1 and of 7.70 ±0.10 in the presence of Lys. Q102 interacts with NADPH and, upon mutation to alanine, leads to destabilization of the C4a-hydroperoxyflavin (FADOOH ). Flavin oxidation with Q102A showed a pKa value of ~8.0. The data are consistent with the pKa of the FAD N5-atom being modulated to a value >9 in the absence of Orn, which aids in the stabilization of FADOOH . Changes in the FAD-N5 environment lead to a decrease in the pKa value, which facilitates elimination of H2 O2 or H2 O. These findings are supported by solvent kinetic isotope effect experiments, which show that proton transfer from the FAD N5-atom is rate limiting in the absence of a substrate, however, is significantly less rate limiting in the presence of Orn and or Lys.
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Affiliation(s)
- Reeder M Robinson
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, 24061
| | - Catherine A Klancher
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, 24061
| | - Pedro J Rodriguez
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, 24061
| | - Pablo Sobrado
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, 24061
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26
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Active site variants provide insight into the nature of conformational changes that accompany the cyclohexanone monooxygenase catalytic cycle. Arch Biochem Biophys 2018; 654:85-96. [DOI: 10.1016/j.abb.2018.07.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 07/16/2018] [Accepted: 07/18/2018] [Indexed: 01/31/2023]
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27
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Matsuda K, Tomita T, Shin-ya K, Wakimoto T, Kuzuyama T, Nishiyama M. Discovery of Unprecedented Hydrazine-Forming Machinery in Bacteria. J Am Chem Soc 2018; 140:9083-9086. [DOI: 10.1021/jacs.8b05354] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Kenichi Matsuda
- Biotechnology Research Center, The University of Tokyo, Tokyo 113-8657, Japan
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Takeo Tomita
- Biotechnology Research Center, The University of Tokyo, Tokyo 113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan
| | - Kazuo Shin-ya
- Biotechnology Research Center, The University of Tokyo, Tokyo 113-8657, Japan
- National Institute of Advanced Industrial Science and Technology (AIST), Tokyo 135-0064, Japan
| | - Toshiyuki Wakimoto
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Tomohisa Kuzuyama
- Biotechnology Research Center, The University of Tokyo, Tokyo 113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan
| | - Makoto Nishiyama
- Biotechnology Research Center, The University of Tokyo, Tokyo 113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan
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28
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Kubitza C, Faust A, Gutt M, Gäth L, Ober D, Scheidig AJ. Crystal structure of pyrrolizidine alkaloid N-oxygenase from the grasshopper Zonocerus variegatus. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2018; 74:422-432. [PMID: 29717713 DOI: 10.1107/s2059798318003510] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 02/28/2018] [Indexed: 11/10/2022]
Abstract
The high-resolution crystal structure of the flavin-dependent monooxygenase (FMO) from the African locust Zonocerus variegatus is presented and the kinetics of structure-based protein variants are discussed. Z. variegatus expresses three flavin-dependent monooxygenase (ZvFMO) isoforms which contribute to a counterstrategy against pyrrolizidine alkaloids (PAs). PAs are protoxic compounds produced by some angiosperm lineages as a chemical defence against herbivores. N-Oxygenation of PAs and the accumulation of PA N-oxides within their haemolymph result in two evolutionary advantages for these insects: (i) they circumvent the defence mechanism of their food plants and (ii) they can use PA N-oxides to protect themselves against predators, which cannot cope with the toxic PAs. Despite a high degree of sequence identity and a similar substrate spectrum, the three ZvFMO isoforms differ greatly in enzyme activity. Here, the crystal structure of the Z. variegatus PA N-oxygenase (ZvPNO), the most active ZvFMO isoform, is reported at 1.6 Å resolution together with kinetic studies of a second isoform, ZvFMOa. This is the first available crystal structure of an FMO from class B (of six different FMO subclasses, A-F) within the family of flavin-dependent monooxygenases that originates from a more highly developed organism than yeast. Despite the differences in sequence between family members, their overall structure is very similar. This indicates the need for high conservation of the three-dimensional structure for this type of reaction throughout all kingdoms of life. Nevertheless, this structure provides the closest relative to the human enzyme that is currently available for modelling studies. Of note, the crystal structure of ZvPNO reveals a unique dimeric arrangement as well as small conformational changes within the active site that have not been observed before. A newly observed kink within helix α8 close to the substrate-binding path might indicate a potential mechanism for product release. The data show that even single amino-acid exchanges in the substrate-entry path, rather than the binding site, have a significant impact on the specific enzyme activity of the isoforms.
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Affiliation(s)
- Christian Kubitza
- Structural Biology, Zoological Institute, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Annette Faust
- Structural Biology, Zoological Institute, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Miriam Gutt
- Biochemical Ecology and Molecular Evolution, Botanical Institute, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Luzia Gäth
- Structural Biology, Zoological Institute, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Dietrich Ober
- Biochemical Ecology and Molecular Evolution, Botanical Institute, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Axel J Scheidig
- Structural Biology, Zoological Institute, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany
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29
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Bufkin K, Sobrado P. Characterization of the Ornithine Hydroxylation Step in Albachelin Biosynthesis. Molecules 2017; 22:E1652. [PMID: 28974024 PMCID: PMC6151521 DOI: 10.3390/molecules22101652] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 09/27/2017] [Accepted: 09/28/2017] [Indexed: 11/16/2022] Open
Abstract
N-Hydroxylating monooxygenases (NMOs) are involved in siderophore biosynthesis. Siderophores are high affinity iron chelators composed of catechol and hydroxamate functional groups that are synthesized and secreted by microorganisms and plants. Recently, a new siderophore named albachelin was isolated from a culture of Amycolatopsis alba growing under iron-limiting conditions. This work focuses on the expression, purification, and characterization of the NMO, abachelin monooxygenase (AMO) from A. alba. This enzyme was purified and characterized in its holo (FAD-bound) and apo (FAD-free) forms. The apo-AMO could be reconstituted by addition of free FAD. The two forms of AMO hydroxylate ornithine, while lysine increases oxidase activity but is not hydroxylated and display low affinity for NADPH.
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Affiliation(s)
- Kendra Bufkin
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA.
- Center for Drug Discovery, Virginia Tech, Blacksburg, VA 24061, USA.
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30
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Abstract
Protein function can be regulated via post-translational modifications by numerous enzymatic and non-enzymatic mechanisms, including oxidation of cysteine and methionine residues. Redox-dependent regulatory mechanisms have been identified for nearly every cellular process, but the major paradigm has been that cellular components are oxidized (damaged) by reactive oxygen species (ROS) in a relatively unspecific way, and then reduced (repaired) by designated reductases. While this scheme may work with cysteine, it cannot be ascribed to other residues, such as methionine, whose reaction with ROS is too slow to be biologically relevant. However, methionine is clearly oxidized in vivo and enzymes for its stereoselective reduction are present in all three domains of life. Here, we revisit the chemistry and biology of methionine oxidation, with emphasis on its generation by enzymes from the monooxygenase family. Particular attention is placed on MICALs, a recently discovered family of proteins that harbor an unusual flavin-monooxygenase domain with an NADPH-dependent methionine sulfoxidase activity. Based on structural and kinetic information we provide a rational framework to explain MICAL mechanism, inhibition, and regulation. Methionine residues that are targeted by MICALs are reduced back by methionine sulfoxide reductases, suggesting that reversible methionine oxidation may be a general mechanism analogous to the regulation by phosphorylation by kinases/phosphatases. The identification of new enzymes that catalyze the oxidation of methionine will open a new area of research at the forefront of redox signaling.
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Affiliation(s)
- Bruno Manta
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Vadim N Gladyshev
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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31
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Zhang Q, Li H, Yu L, Sun Y, Zhu Y, Zhu H, Zhang L, Li SM, Shen Y, Tian C, Li A, Liu HW, Zhang C. Characterization of the flavoenzyme XiaK as an N-hydroxylase and implications in indolosesquiterpene diversification. Chem Sci 2017; 8:5067-5077. [PMID: 28970893 PMCID: PMC5613243 DOI: 10.1039/c7sc01182b] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 04/27/2017] [Indexed: 01/10/2023] Open
Abstract
Flavoenzymes are ubiquitous in biological systems and catalyze a diverse range of chemical transformations.
Flavoenzymes are ubiquitous in biological systems and catalyze a diverse range of chemical transformations. The flavoenzyme XiaK from the biosynthetic pathway of the indolosesquiterpene xiamycin A is demonstrated to mediate the in vivo biotransformation of xiamycin A into multiple products, including a chlorinated adduct as well as dimers characterized by C–N and N–N linkages that are hypothesized to form via radical-based mechanisms. Isolation and characterization of XiaK in vitro shows that it acts as a flavin-dependent N-hydroxylase that catalyzes the hydroxylation of xiamycin A at the carbazole nitrogen to form N-hydroxyxiamycin, a product which was overlooked in earlier in vivo experiments because its chemical and chromatographic properties are similar to those of oxiamycin. N-Hydroxyxiamycin is shown to be unstable under aerobic conditions, and characterization by electron paramagnetic resonance spectroscopy demonstrates formation of an N-hydroxycarbazole radical adduct. This radical species is proposed to serve as a key intermediate leading to the formation of the multiple xiamycin A adducts. This study suggests that non-enzyme catalyzed reactions may play a greater role in the biosynthesis of natural products than has been previously recognized.
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Affiliation(s)
- Qingbo Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology , Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology , Chinese Academy of Sciences , 164 West Xingang Road , Guangzhou 510301 , China . ;
| | - Huixian Li
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology , Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology , Chinese Academy of Sciences , 164 West Xingang Road , Guangzhou 510301 , China . ; .,Institute of Marine Natural Products , School of Marine Sciences , South China Sea Resource Exploitation and Protection Collaborative Innovation Center , Sun Yat-sen University , 135 West Xingang Road , Guangzhou 510006 , China
| | - Lu Yu
- Hefei National Laboratory of Microscale Physical Sciences , School of Life Science , University of Science and Technology of China , Hefei , 230027 , China.,High Magnetic Field Laboratory , Chinese Academy of Sciences , Hefei , 230031 , P. R. China
| | - Yu Sun
- State Key Laboratory of Bioorganic and Natural Products Chemistry , Shanghai Institute of Organic Chemistry , Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , China
| | - Yiguang Zhu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology , Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology , Chinese Academy of Sciences , 164 West Xingang Road , Guangzhou 510301 , China . ;
| | - Hanning Zhu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology , Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology , Chinese Academy of Sciences , 164 West Xingang Road , Guangzhou 510301 , China . ;
| | - Liping Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology , Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology , Chinese Academy of Sciences , 164 West Xingang Road , Guangzhou 510301 , China . ;
| | - Shu-Ming Li
- Institut für Pharmazeutische Biologie und Biotechnologie , Philipps-Universität Marburg , Deutschhausstrasse 17a , 35037 Marburg , Germany
| | - Yuemao Shen
- State Key Laboratory of Microbial Technology , School of Life Science , Shandong University , Jinan 250100 , China
| | - Changlin Tian
- Hefei National Laboratory of Microscale Physical Sciences , School of Life Science , University of Science and Technology of China , Hefei , 230027 , China.,High Magnetic Field Laboratory , Chinese Academy of Sciences , Hefei , 230031 , P. R. China
| | - Ang Li
- State Key Laboratory of Bioorganic and Natural Products Chemistry , Shanghai Institute of Organic Chemistry , Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , China
| | - Hung-Wen Liu
- Division of Chemical Biology and Medicinal Chemistry , College of Pharmacy , Department of Chemistry , University of Texas at Austin , Austin , TX 78712 , USA .
| | - Changsheng Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology , Guangdong Key Laboratory of Marine Materia Medica , South China Sea Institute of Oceanology , Chinese Academy of Sciences , 164 West Xingang Road , Guangzhou 510301 , China . ;
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32
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Waldman AJ, Ng TL, Wang P, Balskus EP. Heteroatom-Heteroatom Bond Formation in Natural Product Biosynthesis. Chem Rev 2017; 117:5784-5863. [PMID: 28375000 PMCID: PMC5534343 DOI: 10.1021/acs.chemrev.6b00621] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Natural products that contain functional groups with heteroatom-heteroatom linkages (X-X, where X = N, O, S, and P) are a small yet intriguing group of metabolites. The reactivity and diversity of these structural motifs has captured the interest of synthetic and biological chemists alike. Functional groups containing X-X bonds are found in all major classes of natural products and often impart significant biological activity. This review presents our current understanding of the biosynthetic logic and enzymatic chemistry involved in the construction of X-X bond containing functional groups within natural products. Elucidating and characterizing biosynthetic pathways that generate X-X bonds could both provide tools for biocatalysis and synthetic biology, as well as guide efforts to uncover new natural products containing these structural features.
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Affiliation(s)
- Abraham J. Waldman
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Tai L. Ng
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Peng Wang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Emily P. Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
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33
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Identification and characterization of a FAD-dependent putrescine N-hydroxylase (GorA) from Gordonia rubripertincta CWB2. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2016.08.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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34
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Martín del Campo JS, Vogelaar N, Tolani K, Kizjakina K, Harich K, Sobrado P. Inhibition of the Flavin-Dependent Monooxygenase Siderophore A (SidA) Blocks Siderophore Biosynthesis and Aspergillus fumigatus Growth. ACS Chem Biol 2016; 11:3035-3042. [PMID: 27588426 DOI: 10.1021/acschembio.6b00666] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aspergillus fumigatus is an opportunistic fungal pathogen and the most common causative agent of fatal invasive mycoses. The flavin-dependent monooxygenase siderophore A (SidA) catalyzes the oxygen and NADPH dependent hydroxylation of l-ornithine (l-Orn) to N5-l-hydroxyornithine in the biosynthetic pathway of hydroxamate-containing siderophores in A. fumigatus. Deletion of the gene that codes for SidA has shown that it is essential in establishing infection in mice models. Here, a fluorescence polarization high-throughput assay was used to screen a 2320 compound library for inhibitors of SidA. Celastrol, a natural quinone methide, was identified as a noncompetitive inhibitor of SidA with a MIC value of 2 μM. Docking experiments suggest that celastrol binds across the NADPH and l-Orn pocket. Celastrol prevents A. fumigatus growth in blood agar. The addition of purified ferric-siderophore abolished the inhibitory effect of celastrol. Thus, celastrol inhibits A. fumigatus growth by blocking siderophore biosynthesis through SidA inhibiton.
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Affiliation(s)
| | - Nancy Vogelaar
- Virginia
Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Karishma Tolani
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Karina Kizjakina
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Kim Harich
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Pablo Sobrado
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Virginia
Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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35
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Li B, Lowe-Power T, Kurihara S, Gonzales S, Naidoo J, MacMillan JB, Allen C, Michael AJ. Functional Identification of Putrescine C- and N-Hydroxylases. ACS Chem Biol 2016; 11:2782-2789. [PMID: 27541336 DOI: 10.1021/acschembio.6b00629] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The small polyamine putrescine (1,4-diaminobutane) is ubiquitously and abundantly found in all three domains of life. It is a precursor, through N-aminopropylation or N-aminobutylation, for biosynthesis of the longer polyamines spermidine, sym-homospermidine, spermine, and thermospermine and longer and branched chain polyamines. Putrescine is also biochemically modified for purposes of metabolic regulation and catabolism, e.g. N-acetylation and N-glutamylation, and for incorporation into specialized metabolites, e.g. N-methylation, N-citrylation, N-palmitoylation, N-hydroxylation, and N-hydroxycinnamoylation. Only one example is known where putrescine is modified on a methylene carbon: the formation of 2-hydroxyputrescine by an unknown C-hydroxylase. Here, we report the functional identification of a previously undescribed putrescine 2-hydroxylase, a Rieske-type nonheme iron sulfur protein from the β-proteobacteria Bordetella bronchiseptica and Ralstonia solanacearum. Identification of the putrescine 2-hydroxylase will facilitate investigation of the physiological functions of 2-hydroxyputrescine. One known role of 2-hydroxyputrescine has direct biomedical relevance: its role in the biosynthesis of the cyclic hydroxamate siderophore alcaligin, a potential virulence factor of the causative agent of whooping cough, Bordetella pertussis. We also report the functional identification of a putrescine N-hydroxylase from the γ-proteobacterium Shewanella oneidensis, which is homologous to FAD- and NADPH-dependent ornithine and lysine N-monooxygenases involved in siderophore biosynthesis. Heterologous expression of the putrescine N-hydroxylase in E. coli produced free N-hydroxyputrescine, never detected previously in a biological system. Furthermore, the putrescine C- and N-hydroxylases identified here could contribute new functionality to polyamine structural scaffolds, including C-H bond functionalization in synthetic biology strategies.
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Affiliation(s)
| | - Tiffany Lowe-Power
- Deptartment of Plant Pathology, University of Wisconsin, Madison, Wisconsin, United States
| | | | | | | | | | - Caitilyn Allen
- Deptartment of Plant Pathology, University of Wisconsin, Madison, Wisconsin, United States
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36
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Mechanism of Rifampicin Inactivation in Nocardia farcinica. PLoS One 2016; 11:e0162578. [PMID: 27706151 PMCID: PMC5051949 DOI: 10.1371/journal.pone.0162578] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 08/24/2016] [Indexed: 12/26/2022] Open
Abstract
A novel mechanism of rifampicin (Rif) resistance has recently been reported in Nocardia farcinica. This new mechanism involves the activity of rifampicin monooxygenase (RifMO), a flavin-dependent monooxygenase that catalyzes the hydroxylation of Rif, which is the first step in the degradation pathway. Recombinant RifMO was overexpressed and purified for biochemical analysis. Kinetic characterization revealed that Rif binding is necessary for effective FAD reduction. RifMO exhibits only a 3-fold coenzyme preference for NADPH over NADH. RifMO catalyzes the incorporation of a single oxygen atom forming an unstable intermediate that eventually is converted to 2'-N-hydroxy-4-oxo-Rif. Stable C4a-hydroperoxyflavin was not detected by rapid kinetics methods, which is consistent with only 30% of the activated oxygen leading to product formation. These findings represent the first reported detailed biochemical characterization of a flavin-monooxygenase involved in antibiotic resistance.
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37
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Abdelwahab H, Robinson R, Rodriguez P, Adly C, El-Sohaimy S, Sobrado P. Identification of structural determinants of NAD(P)H selectivity and lysine binding in lysine N(6)-monooxygenase. Arch Biochem Biophys 2016; 606:180-8. [PMID: 27503802 DOI: 10.1016/j.abb.2016.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 07/22/2016] [Accepted: 08/01/2016] [Indexed: 11/26/2022]
Abstract
l-lysine (l-Lys) N(6)-monooxygenase (NbtG), from Nocardia farcinica, is a flavin-dependent enzyme that catalyzes the hydroxylation of l-Lys in the presence of oxygen and NAD(P)H in the biosynthetic pathway of the siderophore nocobactin. NbtG displays only a 3-fold preference for NADPH over NADH, different from well-characterized related enzymes, which are highly selective for NADPH. The structure of NbtG with bound NAD(P)(+) or l-Lys is currently not available. Herein, we present a mutagenesis study targeting M239, R301, and E216. These amino acids are conserved and located in either the NAD(P)H binding domain or the l-Lys binding pocket. M239R resulted in high production of hydrogen peroxide and little hydroxylation with no change in coenzyme selectivity. R301A caused a 300-fold decrease on kcat/Km value with NADPH but no change with NADH. E216Q increased the Km value for l-Lys by 30-fold with very little change on the kcat value or in the binding of NAD(P)H. These results suggest that R301 plays a major role in NADPH selectivity by interacting with the 2'-phosphate of the adenine-ribose moiety of NADPH, while E216 plays a role in l-Lys binding.
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Affiliation(s)
- Heba Abdelwahab
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA; Department of Chemistry, Faculty of Science, Damietta University, Damietta, 34517, Egypt
| | - Reeder Robinson
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Pedro Rodriguez
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Camelia Adly
- Department of Chemistry, Faculty of Science, Damietta University, Damietta, 34517, Egypt
| | - Sohby El-Sohaimy
- Department of Food Technology, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications, Alexandria, 21934, Egypt
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA 24061, USA; Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, VA 24061, USA.
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38
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Properties and catalytic activities of MICAL1, the flavoenzyme involved in cytoskeleton dynamics, and modulation by its CH, LIM and C-terminal domains. Arch Biochem Biophys 2016; 593:24-37. [DOI: 10.1016/j.abb.2016.01.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 01/25/2016] [Accepted: 01/28/2016] [Indexed: 11/21/2022]
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39
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Robinson R, Qureshi IA, Klancher CA, Rodriguez PJ, Tanner JJ, Sobrado P. Contribution to catalysis of ornithine binding residues in ornithine N5-monooxygenase. Arch Biochem Biophys 2015; 585:25-31. [PMID: 26375201 PMCID: PMC6467063 DOI: 10.1016/j.abb.2015.09.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 08/22/2015] [Accepted: 09/10/2015] [Indexed: 10/23/2022]
Abstract
The SidA ornithine N5-monooxygenase from Aspergillus fumigatus is a flavin monooxygenase that catalyzes the NADPH-dependent hydroxylation of ornithine. Herein we report a mutagenesis study targeting four residues that contact ornithine in crystal structures of SidA: Lys107, Asn293, Asn323, and Ser469. Mutation of Lys107 to Ala abolishes activity as measured in steady-state oxygen consumption and ornithine hydroxylation assays, indicating that the ionic interaction of Lys107 with the carboxylate of ornithine is essential for catalysis. Mutation of Asn293, Asn323, or Ser469 individually to Ala results in >14-fold increases in Km values for ornithine. Asn323 to Ala also increases the rate constant for flavin reduction by NADPH by 18-fold. Asn323 is unique among the four ornithine binding residues in that it also interacts with NADPH by forming a hydrogen bond with the nicotinamide ribose. The crystal structure of N323A complexed with NADP(+) and ornithine shows that the nicontinamide riboside group of NADP is disordered. This result suggests that the increase in flavin reduction rate results from an increase in conformational space available to the enzyme-bound NADP(H). Asn323 thus facilitates ornithine binding at the expense of hindering flavin reduction, which demonstrates the delicate balance that exists within protein-ligand interaction networks in enzyme active sites.
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Affiliation(s)
- Reeder Robinson
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - Insaf A Qureshi
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | | | - Pedro J Rodriguez
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - John J Tanner
- Departments of Biochemistry and Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA.
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA.
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40
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Ren H, Li Q, Zhan Y, Fang X, Yu D. 2,4-Dichlorophenol hydroxylase for chlorophenol removal: Substrate specificity and catalytic activity. Enzyme Microb Technol 2015; 82:74-81. [PMID: 26672451 DOI: 10.1016/j.enzmictec.2015.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 08/11/2015] [Accepted: 08/11/2015] [Indexed: 10/23/2022]
Abstract
Chlorophenols (CPs) are common environmental pollutants. As such, different treatments have been assessed to facilitate their removal. In this study, 2,4-dichlorophenol (2,4-DCP) hydroxylase was used to systematically investigate the activity and removal ability of 19CP congeners at 25 and 0 °C. Results demonstrated that 2,4-DCP hydroxylase exhibited a broad substrate specificity to CPs. The activities of 2,4-DCP hydroxylase against specific CP congeners, including 3-CP, 2,3,6-trichlorophenol, 2-CP, and 2,3-DCP, were higher than those against 2,4-DCP, which is the preferred substrate of previously reported 2,4-DCP hydroxylase. To verify whether cofactors are necessary to promote hydroxylase activity against CP congeners, we added FAD and found that the added FAD induced a 1.33-fold to 5.13-fold significant increase in hydroxylase activity against different CP congeners. The metabolic pathways of the CP degradation in the enzymatic hydroxylation step were preliminarily proposed on the basis of the analyses of the enzymatic activities against 19CP congeners. We found that the high activity and removal rate of 2,4-DCP hydroxylase against CPs at 0 °C enhance the low-temperature-adaptability of this enzyme to the CP congeners; as such, the proposed removal process may be applied to biochemical, bioremediation, and industrial processes, particularly in cold environments.
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Affiliation(s)
- Hejun Ren
- Key Laboratory of Ground Water Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, 2519 Jiefang Road, Changchun 130021, PR China
| | - Qingchao Li
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, College of Life Science, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China
| | - Yang Zhan
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, College of Life Science, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China
| | - Xuexun Fang
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, College of Life Science, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China
| | - Dahai Yu
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, College of Life Science, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China.
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41
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Ren H, Li Q, Fang X, Yu D. Exploring substrate promiscuity of chlorophenol hydroxylase against biphenyl derivatives. RSC Adv 2015. [DOI: 10.1039/c5ra16935f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The substrate promiscuity of 2,4-dichlorophenol hydroxylase against biphenyl derivatives was explored. This enzyme may be used as a potentially useful catalyst in the bioremediation of aromatic contaminants.
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Affiliation(s)
- Hejun Ren
- Key Laboratory of Ground Water Resources and Environment of the Ministry of Education
- College of Environment and Resources
- Jilin University
- Changchun
- P. R. China
| | - Qingchao Li
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education
- College of Life Science
- Jilin University
- Changchun
- P. R. China
| | - Xuexun Fang
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education
- College of Life Science
- Jilin University
- Changchun
- P. R. China
| | - Dahai Yu
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education
- College of Life Science
- Jilin University
- Changchun
- P. R. China
| |
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