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Huang R, Zhi N, Yu L, Li Y, Wu X, He J, Zhu H, Qiao J, Liu X, Tian C, Wang J, Dong M. Genetically Encoded Photosensitizer Protein Reduces Iron–Sulfur Clusters of Radical SAM Enzymes. ACS Catal 2023. [DOI: 10.1021/acscatal.2c05143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Rongrong Huang
- Frontiers Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Ning Zhi
- Frontiers Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Lu Yu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Yaoyang Li
- Frontiers Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Xiangyu Wu
- Frontiers Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Jiale He
- Frontiers Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Hongji Zhu
- Frontiers Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Jianjun Qiao
- Frontiers Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Xiaohong Liu
- Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Changlin Tian
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, Joint Center for Biological Analytical Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jiangyun Wang
- Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Min Dong
- Frontiers Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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Martini MA, Rüdiger O, Breuer N, Nöring B, DeBeer S, Rodríguez-Maciá P, Birrell JA. The Nonphysiological Reductant Sodium Dithionite and [FeFe] Hydrogenase: Influence on the Enzyme Mechanism. J Am Chem Soc 2021; 143:18159-18171. [PMID: 34668697 PMCID: PMC8569811 DOI: 10.1021/jacs.1c07322] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[FeFe] hydrogenases are highly active enzymes for interconverting protons and electrons with hydrogen (H2). Their active site H-cluster is formed of a canonical [4Fe-4S] cluster ([4Fe-4S]H) covalently attached to a unique [2Fe] subcluster ([2Fe]H), where both sites are redox active. Heterolytic splitting and formation of H2 takes place at [2Fe]H, while [4Fe-4S]H stores electrons. The detailed catalytic mechanism of these enzymes is under intense investigation, with two dominant models existing in the literature. In one model, an alternative form of the active oxidized state Hox, named HoxH, which forms at low pH in the presence of the nonphysiological reductant sodium dithionite (NaDT), is believed to play a crucial role. HoxH was previously suggested to have a protonated [4Fe-4S]H. Here, we show that HoxH forms by simple addition of sodium sulfite (Na2SO3, the dominant oxidation product of NaDT) at low pH. The low pH requirement indicates that sulfur dioxide (SO2) is the species involved. Spectroscopy supports binding at or near [4Fe-4S]H, causing its redox potential to increase by ∼60 mV. This potential shift detunes the redox potentials of the subclusters of the H-cluster, lowering activity, as shown in protein film electrochemistry (PFE). Together, these results indicate that HoxH and its one-electron reduced counterpart Hred'H are artifacts of using a nonphysiological reductant, and not crucial catalytic intermediates. We propose renaming these states as the "dithionite (DT) inhibited" states Hox-DTi and Hred-DTi. The broader potential implications of using a nonphysiological reductant in spectroscopic and mechanistic studies of enzymes are highlighted.
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Affiliation(s)
- Maria Alessandra Martini
- Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Olaf Rüdiger
- Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Nina Breuer
- Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Birgit Nöring
- Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Patricia Rodríguez-Maciá
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, U.K
| | - James A Birrell
- Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
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Marshall SA, Fisher K, Ní Cheallaigh A, White MD, Payne KAP, Parker DA, Rigby SEJ, Leys D. Oxidative Maturation and Structural Characterization of Prenylated FMN Binding by UbiD, a Decarboxylase Involved in Bacterial Ubiquinone Biosynthesis. J Biol Chem 2017; 292:4623-4637. [PMID: 28057757 DOI: 10.1074/jbc.m116.762732] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/20/2016] [Indexed: 11/06/2022] Open
Abstract
The activity of the reversible decarboxylase enzyme Fdc1 is dependent on prenylated FMN (prFMN), a recently discovered cofactor. The oxidized prFMN supports a 1,3-dipolar cycloaddition mechanism that underpins reversible decarboxylation. Fdc1 is a distinct member of the UbiD family of enzymes, with the canonical UbiD catalyzing the (de)carboxylation of para-hydroxybenzoic acid-type substrates. Here we show that the Escherichia coli UbiD enzyme, which is implicated in ubiquinone biosynthesis, cannot be isolated in an active holoenzyme form despite the fact active holoFdc1 is readily obtained. Formation of holoUbiD requires reconstitution in vitro of the apoUbiD with reduced prFMN. Furthermore, although the Fdc1 apoenzyme can be readily reconstituted and activated, in vitro oxidation to the mature prFMN cofactor stalls at formation of a radical prFMN species in holoUbiD. Further oxidative maturation in vitro occurs only at alkaline pH, suggesting a proton-coupled electron transfer precedes formation of the fully oxidized prFMN. Crystal structures of holoUbiD reveal a relatively open active site potentially occluded from solvent through domain motion. The presence of a prFMN sulfite-adduct in one of the UbiD crystal structures confirms oxidative maturation does occur at ambient pH on a slow time scale. Activity could not be detected for a range of putative para-hydroxybenzoic acid substrates tested. However, the lack of an obvious hydrophobic binding pocket for the octaprenyl tail of the proposed ubiquinone precursor substrate does suggest UbiD might act on a non-prenylated precursor. Our data reveals an unexpected variation occurs in domain mobility, prFMN binding, and maturation by the UbiD enzyme family.
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Affiliation(s)
- Stephen A Marshall
- From the Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street Manchester, M1 7DN, United Kingdom and
| | - Karl Fisher
- From the Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street Manchester, M1 7DN, United Kingdom and
| | - Aisling Ní Cheallaigh
- From the Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street Manchester, M1 7DN, United Kingdom and
| | - Mark D White
- From the Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street Manchester, M1 7DN, United Kingdom and
| | - Karl A P Payne
- From the Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street Manchester, M1 7DN, United Kingdom and
| | - D A Parker
- Innovation/Biodomain, Shell International Exploration and Production, Westhollow Technology Center, Houston, Texas 77082-3101
| | - Stephen E J Rigby
- From the Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street Manchester, M1 7DN, United Kingdom and
| | - David Leys
- From the Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street Manchester, M1 7DN, United Kingdom and
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Lei B, Ding Q, Tu SC. Identity of the emitter in the bacterial luciferase luminescence reaction: binding and fluorescence quantum yield studies of 5-decyl-4a-hydroxy-4a,5-dihydroriboflavin-5'-phosphate as a model. Biochemistry 2005; 43:15975-82. [PMID: 15595854 DOI: 10.1021/bi0480640] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The excited state of 4a-hydroxy-4a,5-dihydroFMN has been postulated to be the emitter in the bacterial bioluminescence reaction. However, while the bioluminescence quantum yield of the luciferase emitter is about 0.16, chemiluminescence and fluorescence quantum yields of earlier flavin models mimicking the luciferase emitter were no more than 10(-5). To further examine the proposed chemical identity of the luciferase emitter, 5-decyl-4a-hydroxy-4a,5-dihydroFMN was prepared as a new flavin model. Both the wild-type Vibrio harveyi luciferase and a catalytically active alphaC106A mutant formed complexes with the flavin model at a 1:1 molar ratio with K(d) values at 2.4 and 1.2 microM, respectively. This flavin model inhibited the activity of both luciferases, suggesting that it was bound to the enzyme active center. While the free flavin model was itself only very weakly fluorescent, its binding to either luciferase species resulted in markedly enhanced fluorescence, peaking at 440 nm. The fluorescence quantum yields of 5-decyl-4a-hydroxy-4a,5-dihydroFMN bound to wild-type and alphaC106A luciferases were 0.08 and 0.05, respectively, which are about 50% of the respective emitter bioluminescence quantum yields of these two luciferases. The present findings clearly demonstrated that the luciferase active site was suitable for marked enhancement of fluorescence of 4a-hydroxyflavin and, hence, provides a strong support to the proposed identity of 4a-hydroxy-4a,5-dihydroFMN, in its exited state, as the luciferase emitter.
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Affiliation(s)
- Benfang Lei
- Department of Biology, University of Houston, Houston, Texas 77204-5001, USA
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Wei CJ, Lei B, Tu SC. Characterization of the binding of Photobacterium phosphoreum P-flavin by Vibrio harveyi Luciferase. Arch Biochem Biophys 2001; 396:199-206. [PMID: 11747297 DOI: 10.1006/abbi.2001.2612] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The isolated Photobacterium phosphoreum luciferase is associated with a bound flavin designated P-flavin and tentatively identified as 6-(3"-myristic acid)-FMN. Since FMN and myristic acid are products of the normal luciferase reaction, we explored the possibility that P-flavin can also be bound by luciferase from other luminous bacteria and serve as an active site probe. P-flavin has never been detected in Vibrio harveyi cells. We found that the V. harveyi luciferase binds P. phosphoreum P-flavin, at a ratio of 1 P-flavin per luciferase alphabeta dimer, and with concomitant absorption spectral perturbation of P-flavin, fluorescence quenching of P-flavin and luciferase, and activity inhibition of luciferase. Isolated P-flavin can be fully reduced photochemically. V. harveyi luciferase bound the oxidized P-flavin with a K(d) (or K(i) competitively against decanal) of 0.1-0.16 microM, which is three orders of magnitude lower than the K(d) for FMN binding but similar to that of reduced FMN binding. The reduced P-flavin exhibited a K(i) (competitively against the reduced FMN substrate) of 0.16 microM, also similar to the K(d) for reduced FMN. Hence, the covalent attachment of myristic acid to FMN greatly and preferentially enhanced the binding of oxidized P-flavin. The dissociation of P-flavin was slow in comparison with the binding of reduced FMN and decanal substrates. Modification of the alphaCys106 near the active site by N-ethylmaleimide can be retarded by P-flavin. These findings indicate that P-flavin is potentially a superb active site probe for luciferase. We hypothesize that P-flavin is a by-product of luciferase generated by a side reaction which is trivial with the V. harveyi luciferase but significant in the P. phosphoreum luciferase-catalyzed reaction.
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Affiliation(s)
- C J Wei
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA
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Mager HI, Tu SC. Aromatic hydroxylations by flavins: evidence on direct attack of phenylalanine by flavin radical species. Tetrahedron 1994. [DOI: 10.1016/s0040-4020(01)80687-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Lei BF, Becvar JE. A new reducing agent of flavins and its application to the assay of bacterial luciferase. Photochem Photobiol 1991; 54:473-6. [PMID: 1784643 DOI: 10.1111/j.1751-1097.1991.tb02043.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Copper(I) plus ethylenediaminetetraacetic acid, Cu(I)-EDTA, reduces flavins. Using Cu(I)-EDTA reduction of riboflavin 5'-phosphate, a new assay method for bacterial luciferase is established. In previous assay methods, flavin and aldehyde substrates for luciferase have been routinely added to luciferase at different times; the new assay permits aldehyde and Cu(I)-reduced flavin to be injected simultaneously into air-saturated buffer containing luciferase. In the new assay method using Cu(I), bovine serum albumin is not required, the initial emission intensity is more than twice and the overall yield is about twice of that in the so-called standard assay for luciferase.
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Affiliation(s)
- B F Lei
- Department of Chemistry, University of Texas, El Paso 79968
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Mager HI, Tu SC, Liu YH, Deng YJ, Kadish KM. Electrochemical superoxidation of flavins: generation of active precursors in luminescent model systems. Photochem Photobiol 1990; 52:1049-56. [PMID: 1962857 DOI: 10.1111/j.1751-1097.1990.tb01825.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Using 3-methyllumiflavin and tetraacetyliriboflavin as examples, we have shown that the socalled "fully oxidized" flavins can be "superoxidized" at an anodic potential of 1.8 to 1.9 V giving flavin radical cation transients which are rapidly transformed in subsequent chemical reactions. An attack by H2O subsequent to the superoxidation of 3-methyllumiflavin provides a route for the formation of 4a-hydroxy-3-methyllumiflavin radical cation, as evident from the subsequent decomposition to the protonated form of the starting flavin. When 3-methyllumiflavin is superoxidized in the presence of a base, a recycling process occurs, allowing superoxidized flavin to be trapped in a slower, competitive conversion. The relatively more stable trapped product is active in reacting with H2O2 to emit chemiluminescence. Electrochemical oxidation of H2O2 in acetonitrile at 1.30 V in the presence of an oxidized flavin results in a direct protonation of the flavin by H+ generated from the electrolysis of H2O2. Minor reactions presumably provide alternative formations of the 4a-hydroperoxy- and 4a-hydroxy-flavin radical cation transients by the direct addition of HOO. and HO. radicals, which also arise in the oxidation of H2O2, to protonated flavin. Under such conditions the superoxidized flavin radical cation is apparently also formed, either directly or by process(es) such as decomposition of the flavin 4a-adduct radical cations. Subsequent reductions of either the superoxidized flavin or the flavin 4a-adduct radical cations lead to an almost steady level of luminescence.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H I Mager
- Department of Biochemical and Biophysical Sciences, University of Houston, TX 77204
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