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Faustino M, Lourenço T, Strobbe S, Cao D, Fonseca A, Rocha I, Van Der Straeten D, Oliveira MM. Mathematical kinetic modelling followed by in vitro and in vivo assays reveal the bifunctional rice GTPCHII/DHBPS enzymes and demonstrate the key roles of OsRibA proteins in the vitamin B2 pathway. BMC PLANT BIOLOGY 2024; 24:220. [PMID: 38532321 DOI: 10.1186/s12870-024-04878-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/03/2024] [Indexed: 03/28/2024]
Abstract
BACKGROUND Riboflavin is the precursor of several cofactors essential for normal physical and cognitive development, but only plants and some microorganisms can produce it. Humans thus rely on their dietary intake, which at a global level is mainly constituted by cereals (> 50%). Understanding the riboflavin biosynthesis players is key for advancing our knowledge on this essential pathway and can hold promise for biofortification strategies in major crop species. In some bacteria and in Arabidopsis, it is known that RibA1 is a bifunctional protein with distinct GTP cyclohydrolase II (GTPCHII) and 3,4-dihydroxy-2-butanone-4-phosphate synthase (DHBPS) domains. Arabidopsis harbors three RibA isoforms, but only one retained its bifunctionality. In rice, however, the identification and characterization of RibA has not yet been described. RESULTS Through mathematical kinetic modeling, we identified RibA as the rate-limiting step of riboflavin pathway and by bioinformatic analysis we confirmed that rice RibA proteins carry both domains, DHBPS and GTPCHII. Phylogenetic analysis revealed that OsRibA isoforms 1 and 2 are similar to Arabidopsis bifunctional RibA1. Heterologous expression of OsRibA1 completely restored the growth of the rib3∆ yeast mutant, lacking DHBPS expression, while causing a 60% growth improvement of the rib1∆ mutant, lacking GTPCHII activity. Regarding OsRibA2, its heterologous expression fully complemented GTPCHII activity, and improved rib3∆ growth by 30%. In vitro activity assays confirmed that both OsRibA1 and OsRibA2 proteins carry GTPCHII/DHBPS activities, but that OsRibA1 has higher DHBPS activity. The overexpression of OsRibA1 in rice callus resulted in a 28% increase in riboflavin content. CONCLUSIONS Our study elucidates the critical role of RibA in rice riboflavin biosynthesis pathway, establishing it as the rate-limiting step in the pathway. By identifying and characterizing OsRibA1 and OsRibA2, showcasing their GTPCHII and DHBPS activities, we have advanced the understanding of riboflavin biosynthesis in this staple crop. We further demonstrated that OsRibA1 overexpression in rice callus increases its riboflavin content, providing supporting information for bioengineering efforts.
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Affiliation(s)
- Maria Faustino
- Laboratory of Plant Functional Genomics, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, 2780-157, Portugal
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K. L. Ledeganckstraat 35, Gent, B-9000, Belgium
| | - Tiago Lourenço
- Laboratory of Plant Functional Genomics, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, 2780-157, Portugal
| | - Simon Strobbe
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K. L. Ledeganckstraat 35, Gent, B-9000, Belgium
- University of Geneva, Quai E. Ansermet 30, Geneva, 1211, Switzerland
| | - Da Cao
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K. L. Ledeganckstraat 35, Gent, B-9000, Belgium
| | - André Fonseca
- Laboratory of Systems and Synthetic Biology, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, 2780-157, Portugal
| | - Isabel Rocha
- Laboratory of Systems and Synthetic Biology, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, 2780-157, Portugal
| | - Dominique Van Der Straeten
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K. L. Ledeganckstraat 35, Gent, B-9000, Belgium.
| | - M Margarida Oliveira
- Laboratory of Plant Functional Genomics, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, 2780-157, Portugal.
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Phintha A, Chaiyen P. Unifying and versatile features of flavin-dependent monooxygenases: Diverse catalysis by a common C4a-(hydro)peroxyflavin. J Biol Chem 2023; 299:105413. [PMID: 37918809 PMCID: PMC10696468 DOI: 10.1016/j.jbc.2023.105413] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/18/2023] [Accepted: 10/22/2023] [Indexed: 11/04/2023] Open
Abstract
Flavin-dependent monooxygenases (FDMOs) are known for their remarkable versatility and for their crucial roles in various biological processes and applications. Extensive research has been conducted to explore the structural and functional relationships of FDMOs. The majority of reported FDMOs utilize C4a-(hydro)peroxyflavin as a reactive intermediate to incorporate an oxygen atom into a wide range of compounds. This review discusses and analyzes recent advancements in our understanding of the structural and mechanistic features governing the enzyme functions. State-of-the-art discoveries related to common and distinct structural properties governing the catalytic versatility of the C4a-(hydro)peroxyflavin intermediate in selected FDMOs are discussed. Specifically, mechanisms of hydroxylation, dehalogenation, halogenation, and light-emitting reactions by FDMOs are highlighted. We also provide new analysis based on the structural and mechanistic features of these enzymes to gain insights into how the same intermediate can be harnessed to perform a wide variety of reactions. Challenging questions to obtain further breakthroughs in the understanding of FDMOs are also proposed.
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Affiliation(s)
- Aisaraphon Phintha
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, Thailand.
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Zhang X, Wang Z, Li Z, Shaik S, Wang B. [4Fe–4S]-Mediated Proton-Coupled Electron Transfer Enables the Efficient Degradation of Chloroalkenes by Reductive Dehalogenases. ACS Catal 2023. [DOI: 10.1021/acscatal.2c06306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Xuan Zhang
- State Key Laboratory Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Zikuan Wang
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Zhen Li
- State Key Laboratory Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Sason Shaik
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Binju Wang
- State Key Laboratory Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
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Hu WY, Li K, Weitz A, Wen A, Kim H, Murray JC, Cheng R, Chen B, Naowarojna N, Grinstaff MW, Elliott SJ, Chen JS, Liu P. Light-Driven Oxidative Demethylation Reaction Catalyzed by a Rieske-Type Non-heme Iron Enzyme Stc2. ACS Catal 2022; 12:14559-14570. [PMID: 37168530 PMCID: PMC10168674 DOI: 10.1021/acscatal.2c04232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rieske-type non-heme iron oxygenases/oxidases catalyze a wide range of transformations. Their applications in bioremediation or biocatalysis face two key barriers: the need of expensive NAD(P)H as a reductant and a proper reductase to mediate the electron transfer from NAD(P)H to the oxygenases. To bypass the need of both the reductase and NAD(P)H, using Rieske-type oxygenase (Stc2) catalyzed oxidative demethylation as the model system, we report Stc2 photocatalysis using eosin Y/sulfite as the photosensitizer/sacrificial reagent pair. In a flow-chemistry setting to separate the photo-reduction half-reaction and oxidation half-reaction, Stc2 photo-biocatalysis outperforms the Stc2-NAD(P)H-reductase (GbcB) system. In addition, in a few other selected Rieske enzymes (NdmA, CntA, and GbcA), and a flavin-dependent enzyme (iodotyrosine deiodinase, IYD), the eosin Y/sodium sulfite photo-reduction pair could also serve as the NAD(P)H-reductase surrogate to support catalysis, which implies the potential applicability of this photo-reduction system to other redox enzymes.
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Affiliation(s)
- Wei-Yao Hu
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai200240, P. R. China
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Kelin Li
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Andrew Weitz
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Aiwen Wen
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Hyomin Kim
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Jessica C. Murray
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Ronghai Cheng
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Baixiong Chen
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Nathchar Naowarojna
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Mark W. Grinstaff
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Sean J. Elliott
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
| | - Jie-Sheng Chen
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai200240, P. R. China
| | - Pinghua Liu
- Department of Chemistry, Boston University, Boston, Massachusetts02215, United States
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Pimviriyakul P, Jaruwat A, Chitnumsub P, Chaiyen P. Structural insights into a flavin-dependent dehalogenase HadA explain catalysis and substrate inhibition via quadruple π-stacking. J Biol Chem 2021; 297:100952. [PMID: 34252455 PMCID: PMC8342789 DOI: 10.1016/j.jbc.2021.100952] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/24/2021] [Accepted: 07/08/2021] [Indexed: 12/20/2022] Open
Abstract
HadA is a flavin-dependent monooxygenase catalyzing hydroxylation plus dehalogenation/denitration, which is useful for biodetoxification and biodetection. In this study, the X-ray structure of wild-type HadA (HadAWT) co-complexed with reduced FAD (FADH-) and 4-nitrophenol (4NP) (HadAWT-FADH--4NP) was solved at 2.3-Å resolution, providing the first full package (with flavin and substrate bound) structure of a monooxygenase of this type. Residues Arg101, Gln158, Arg161, Thr193, Asp254, Arg233, and Arg439 constitute a flavin-binding pocket, whereas the 4NP-binding pocket contains the aromatic side chain of Phe206, which provides π-π stacking and also is a part of the hydrophobic pocket formed by Phe155, Phe286, Thr449, and Leu457. Based on site-directed mutagenesis and stopped-flow experiments, Thr193, Asp254, and His290 are important for C4a-hydroperoxyflavin formation with His290, also serving as a catalytic base for hydroxylation. We also identified a novel structural motif of quadruple π-stacking (π-π-π-π) provided by two 4NP and two Phe441 from two subunits. This motif promotes 4NP binding in a nonproductive dead-end complex, which prevents C4a-hydroperoxy-FAD formation when HadA is premixed with aromatic substrates. We also solved the structure of the HadAPhe441Val-FADH--4NP complex at 2.3-Å resolution. Although 4NP can still bind to this variant, the quadruple π-stacking motif was disrupted. All HadAPhe441 variants lack substrate inhibition behavior, confirming that quadruple π-stacking is a main cause of dead-end complex formation. Moreover, the activities of these HadAPhe441 variants were improved by ⁓20%, suggesting that insights gained from the flavin-dependent monooxygenases illustrated here should be useful for future improvement of HadA's biocatalytic applications.
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Affiliation(s)
- Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Aritsara Jaruwat
- National Center for Genetic Engineering and Biotechnology, Pathumthani, Thailand
| | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology, Pathumthani, Thailand.
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand.
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Sobrado P. Role of reduced flavin in dehalogenation reactions. Arch Biochem Biophys 2020; 697:108696. [PMID: 33245912 DOI: 10.1016/j.abb.2020.108696] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 11/12/2020] [Accepted: 11/18/2020] [Indexed: 12/14/2022]
Abstract
Halogenated organic compounds are extensively used in the cosmetic, pharmaceutical, and chemical industries. Several naturally occurring halogen-containing natural products are also produced, mainly by marine organisms. These compounds accumulate in the environment due to their chemical stability and lack of biological pathways for their degradation. However, a few enzymes have been identified that perform dehalogenation reactions in specific biological pathways and others have been identified to have secondary activities toward halogenated compounds. Various mechanisms for dehalogenation of I, Cl, Br, and F containing compounds have been elucidated. These have been grouped into reductive, oxidative, and hydrolytic mechanisms. Flavin-dependent enzymes have been shown to catalyze oxidative dehalogenation reactions utilizing the C4a-hydroperoxyflavin intermediate. In addition, flavoenzymes perform reductive dehalogenation, forming transient flavin semiquinones. Recently, flavin-dependent enzymes have also been shown to perform dehalogenation reactions where the reduced form of the flavin produces a covalent intermediate. Here, recent studies on the reactions of flavoenzymes in dehalogenation reactions, with a focus on covalent catalytic dehalogenation mechanisms, are described.
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Affiliation(s)
- Pablo Sobrado
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, VA, 24061, USA.
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