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Lesanavičius M, Seo D, Maurutytė G, Čėnas N. Redox Properties of Bacillus subtilis Ferredoxin:NADP + Oxidoreductase: Potentiometric Characteristics and Reactions with Pro-Oxidant Xenobiotics. Int J Mol Sci 2024; 25:5373. [PMID: 38791410 PMCID: PMC11121358 DOI: 10.3390/ijms25105373] [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: 03/28/2024] [Revised: 05/03/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Bacillus subtilis ferredoxin:NADP+ oxidoreductase (BsFNR) is a thioredoxin reductase-type FNR whose redox properties and reactivity with nonphysiological electron acceptors have been scarcely characterized. On the basis of redox reactions with 3-acetylpyridine adenine dinucleotide phosphate, the two-electron reduction midpoint potential of the flavin adenine dinucleotide (FAD) cofactor was estimated to be -0.240 V. Photoreduction using 5-deazaflavin mononucleotide (5-deazaFMN) as a photosensitizer revealed that the difference in the redox potentials between the first and second single-electron transfer steps was 0.024 V. We examined the mechanisms of the reduction of several different groups of non-physiological electron acceptors catalyzed by BsFNR. The reactivity of quinones and aromatic N-oxides toward BsFNR increased when increasing their single-electron reduction midpoint redox potentials. The reactivity of nitroaromatic compounds was lower due to their lower electron self-exchange rate, but it exhibited the same trend. A mixed single- and two-electron reduction reaction was characteristic of quinones, whereas reactions involving nitroaromatics proceeded exclusively via the one-electron reduction reaction. The oxidation of FADH• to FAD is the rate-limiting step during the oxidation of fully reduced FAD. The calculated electron transfer distances in the reaction with nitroaromatics were close to those of other FNRs including the plant-type enzymes, thus demonstrating their similar active site accessibility to low-molecular-weight oxidants despite the fundamental differences in their structures.
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Affiliation(s)
- Mindaugas Lesanavičius
- Department of Xenobiotics Biochemistry, Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio Av. 7, LT-10257 Vilnius, Lithuania; (M.L.); (G.M.)
| | - Daisuke Seo
- Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan;
| | - Gintarė Maurutytė
- Department of Xenobiotics Biochemistry, Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio Av. 7, LT-10257 Vilnius, Lithuania; (M.L.); (G.M.)
| | - Narimantas Čėnas
- Department of Xenobiotics Biochemistry, Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio Av. 7, LT-10257 Vilnius, Lithuania; (M.L.); (G.M.)
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2
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Seo D. The Role of the si-Face Tyrosine of a Homodimeric Ferredoxin-NADP + Oxidoreductase from Bacillus subtilis during Complex Formation and Redox Equivalent Transfer with NADP +/H and Ferredoxin. Antioxidants (Basel) 2023; 12:1741. [PMID: 37760044 PMCID: PMC10526003 DOI: 10.3390/antiox12091741] [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: 07/18/2023] [Revised: 08/18/2023] [Accepted: 08/28/2023] [Indexed: 09/29/2023] Open
Abstract
In the crystal structure of ferredoxin-NADP+ oxidoreductase from Bacillus subtilis (BsFNR), Tyr50 stacks on the si-face of the isoalloxazine ring portion of the FAD prosthetic group. This configuration is highly conserved among the homodimeric ferredoxin-NAD(P)+ oxidoreductases (FNR) from Gram-positive bacteria and photosynthetic bacteria. In this report, pre-steady state reactions of Tyr50 variants with NADP+/NADPH and ferredoxin from B. subtilis (BsFd) were examined with stopped-flow spectrophotometry to assess the effects of the mutation on the formation of FNR-substrate complexes and following redox equivalent transfer. Mixing oxidized BsFNRs with NADPH resulted in a rapid complex formation followed by a rate-limiting hydride transfer. The substitution substantially modulated the intensity of the charge transfer absorption band and decreased the observed hydride transfer rates compared to the wild type. Reduction of the Y50W mutant by NADPH proceeded in a monophasic manner, while the Y50G and Y50S mutants did in biphasic phases. The reduced Tyr50 mutants hardly promoted the reduction of NADP+. Mixing oxidized BsFNRs with reduced BsFd resulted in the reduction of the FNRs. The observed FNR reduction rates of the three variants were comparable, but in the Y50G and Y50S mutants, the amount of the reduced FNR at the rapid phase was decreased, and a slow FNR reduction phase was observed. The obtained results suggest that the replacements of Tyr50 with Gly and Ser permitted the conformational change in the reduced form, which induced an asymmetric kinetic behavior between the protomers of the homodimeric BsFNR.
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Affiliation(s)
- Daisuke Seo
- Division of Material Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
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3
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Zhuang B, Aleksandrov A, Seo D, Vos MH. Excited-State Properties of Fully Reduced Flavins in Ferredoxin-NADP + Oxidoreductase. J Phys Chem Lett 2023; 14:1096-1102. [PMID: 36700861 DOI: 10.1021/acs.jpclett.2c03741] [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: 06/17/2023]
Abstract
The fully reduced flavin cofactor (FADred) in ferredoxin-NADP+ oxidoreductase (FNR) is a functional intermediate that displays different catalytic and steady-state spectral properties for enzymes from Bacillus subtilis (BsFNR), Chlorobaculum tepidum (CtFNR), and Rhodopseudomonas palustris (RpFNR). Using ultrafast spectroscopy, we reveal that at physiological pH, photoexcited FADred in BsFNR and RpFNR exhibits unprecedentedly fast decays (dominantly in 6 and 8 ps, respectively), whereas in CtFNR the decay is much slower (∼400 ps), as in other flavoproteins. Correlating these observations with the protonation states of FADred and the dynamic properties of the protein environment, we conclude that the excited state of neutral FADred can be intrinsically short-lived even in proteins, contrasting with the well-documented behavior of the anionic form that systematically displays markedly increased excited-state lifetime upon binding to proteins. This work provides new insight into the photochemistry of fully reduced flavins, which are emerging as functional initial states in bioengineered photocatalysts.
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Affiliation(s)
- Bo Zhuang
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Alexey Aleksandrov
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Daisuke Seo
- Division of Material Science, Graduate School of Natural Science and Technology, Kanazawa University, 920-1192 Kanazawa, Ishikawa, Japan
| | - Marten H Vos
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
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4
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Zhuang B, Vos MH. Photoswitching Behavior of Flavin-Inhibitor Complex in a Nonphotocatalytic Flavoenzyme. J Am Chem Soc 2022; 144:11569-11573. [PMID: 35727223 DOI: 10.1021/jacs.2c04763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
An unprecedented photoswitching phenomenon of flavin-inhibitor complexes in a flavoenzyme was revealed by femtosecond transient absorption spectroscopy. The vast majority of flavoenzymes, including monomeric sarcosine oxidase (MSOX), perform non-light-driven physiological functions. Yet, the participation of flavin cofactors in photoinduced electron transfer reactions is widespread. MSOX catalyzes the oxidative demethylation of sarcosine; methylthioacetate (MTA) is a substrate analog inhibitor that forms a complex with MSOX exhibiting intense absorption bands over the whole visible range due to flavin-MTA charge transfer (CT) interactions. Here, we demonstrate that upon excitation, these CT interactions vanish during a barrierless high quantum yield reaction in ∼300 fs. The initial complex subsequently geminately re-forms in a few nanoseconds near room temperature in a thermally activated way with an activation energy of 28 kJ/mol. We attribute this hitherto undocumented process to a well-defined photoinduced isomerization of MTA in the active site, as corroborated by experiments with the heavier ligand methylselenoacetate. Photoisomerization phenomena involving CT transitions may be further explored in photocatalytic and photoswitching applications of flavoenzymes.
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Affiliation(s)
- Bo Zhuang
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Marten H Vos
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
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Thioredoxin Reductase-Type Ferredoxin: NADP+ Oxidoreductase of Rhodopseudomonas palustris: Potentiometric Characteristics and Reactions with Nonphysiological Oxidants. Antioxidants (Basel) 2022; 11:antiox11051000. [PMID: 35624864 PMCID: PMC9137726 DOI: 10.3390/antiox11051000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 11/17/2022] Open
Abstract
Rhodopseudomonas palustris ferredoxin:NADP+ oxidoreductase (RpFNR) belongs to a novel group of thioredoxin reductase-type FNRs with partly characterized redox properties. Based on the reactions of RpFNR with the 3-acetylpyridine adenine dinucleotide phosphate redox couple, we estimated the two-electron reduction midpoint potential of the FAD cofactor to be −0.285 V. 5-Deaza-FMN-sensitized photoreduction revealed −0.017 V separation of the redox potentials between the first and second electron transfer events. We examined the mechanism of oxidation of RpFNR by several different groups of nonphysiological electron acceptors. The kcat/Km values of quinones and aromatic N-oxides toward RpFNR increase with their single-electron reduction midpoint potential. The lower reactivity, mirroring their lower electron self-exchange rate, is also seen to have a similar trend for nitroaromatic compounds. A mixed single- and two-electron reduction was characteristic of quinones, with single-electron reduction accounting for 54% of the electron flux, whereas nitroaromatics were reduced exclusively via single-electron reduction. It is highly possible that the FADH· to FAD oxidation reaction is the rate-limiting step during the reoxidation of reduced FAD. The calculated electron transfer distances in the reaction with quinones and nitroaromatics were close to those of Anabaena and Plasmodium falciparum FNRs, thus demonstrating their similar “intrinsic” reactivity.
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Anaerobic Stopped-Flow Spectrophotometry with Photodiode Array Detection in the Presteady State: An Application to Elucidate Oxidoreduction Mechanisms in Flavoproteins. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2021; 2280:135-155. [PMID: 33751433 DOI: 10.1007/978-1-0716-1286-6_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Anaerobic stopped-flow (SF) spectrophotometry is a powerful biophysical tool that allows a complete kinetic characterization of protein interactions with other molecules when they are in different redox states, as well as of the redox processes consequence of such interactions. Differences in the absorption spectroscopic properties of oxidized, semiquinone and hydroquinone states of flavoproteins, as well as the appearance of transient spectroscopic features produced by the flavin cofactor during substrate binding and electron transfer processes, have made SF a suitable technique for kinetically dissecting their mechanisms of reaction. In addition, SF coupled to photodiode array detection, enables kinetic data collection in a wavelength range. When such type of data are available for a flavoprotein reaction, they allow for obtaining detailed information of individual reaction steps, including intermolecular dissociation constants as well as electron transfer rate constants. Methodologies for the mechanistic characterization of flavoproteins involved in redox processes by SF spectrophotometry are described in this chapter.
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Zhuang B, Seo D, Aleksandrov A, Vos MH. Characterization of Light-Induced, Short-Lived Interacting Radicals in the Active Site of Flavoprotein Ferredoxin-NADP + Oxidoreductase. J Am Chem Soc 2021; 143:2757-2768. [PMID: 33591179 DOI: 10.1021/jacs.0c09627] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Radicals of flavin adenine dinucleotide (FAD), as well as tyrosine and tryptophan, are widely involved as key reactive intermediates during electron-transfer (ET) reactions in flavoproteins. Due to the high reactivity of these species and their corresponding short lifetime, characterization of these intermediates in functional processes of flavoproteins is usually challenging but can be achieved by ultrafast spectroscopic studies of light-activatable flavoproteins. In ferredoxin-NADP+ oxidoreductase from Bacillus subtilis (BsFNR), fluorescence of the FAD cofactor that very closely interacts with a neighboring tyrosine residue (Tyr50) is strongly quenched. Here we study short-lived photoproducts of this enzyme and its variants, with Tyr50 replaced by tryptophan or glycine. Using time-resolved fluorescence and absorption spectroscopies, we show that, upon the excitation of WT BsFNR, ultrafast ET from Tyr50 to the excited FAD cofactor occurs in ∼260 fs, an order of magnitude faster than the decay by charge recombination, facilitating the characterization of the reaction intermediates in the charge-separated state with respect to other recently studied systems. These studies are corroborated by experiments on the Y50W mutant protein, which yield photoproducts qualitatively similar to those observed in other tryptophan-bearing flavoproteins. By combining the experimental results with molecular dynamics simulations and quantum mechanics calculations, we investigate in detail the effects of protein environment and relaxations on the spectral properties of those radical intermediates and demonstrate that the spectral features of radical anionic FAD are highly sensitive to its environment, and in particular to the dynamics and nature of the counterions formed in the photoproducts. Altogether, comprehensive characterizations are provided for important radical intermediates that are generally involved in functional processes of flavoproteins.
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Affiliation(s)
- Bo Zhuang
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Daisuke Seo
- Division of Material Science, Graduate School of Natural Science and Technology, Kanazawa University, 920-1192 Kanazawa, Ishikawa, Japan
| | - Alexey Aleksandrov
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Marten H Vos
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
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Rubredoxin from the green sulfur bacterium Chlorobaculum tepidum donates a redox equivalent to the flavodiiron protein in an NAD(P)H dependent manner via ferredoxin-NAD(P) + oxidoreductase. Arch Microbiol 2020; 203:799-808. [PMID: 33051772 DOI: 10.1007/s00203-020-02079-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 09/24/2020] [Accepted: 10/01/2020] [Indexed: 10/23/2022]
Abstract
The green sulfur bacterium, Chlorobaculum tepidum, is an anaerobic photoautotroph that performs anoxygenic photosynthesis. Although genes encoding rubredoxin (Rd) and a putative flavodiiron protein (FDP) were reported in the genome, a gene encoding putative NADH-Rd oxidoreductase is not identified. In this work, we expressed and purified the recombinant Rd and FDP and confirmed dioxygen reductase activity in the presence of ferredoxin-NAD(P)+ oxidoreductase (FNR). FNR from C. tepidum and Bacillus subtilis catalyzed the reduction of Rd at rates comparable to those reported for NADH-Rd oxidoreductases. Also, we observed substrate inhibition at high concentrations of NADPH similar to that observed with ferredoxins. In the presence of NADPH, B. subtilis FNR and Rd, FDP promoted dioxygen reduction at rates comparable to those reported for other bacterial FDPs. Taken together, our results suggest that Rd and FDP participate in the reduction of dioxygen in C. tepidum and that FNR can promote the reduction of Rd in this bacterium.
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Seo D, Muraki N, Kurisu G. Kinetic and structural insight into a role of the re-face Tyr328 residue of the homodimer type ferredoxin-NADP + oxidoreductase from Rhodopseudomonas palustris in the reaction with NADP +/NADPH. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1861:148140. [PMID: 31838096 DOI: 10.1016/j.bbabio.2019.148140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 11/08/2019] [Accepted: 12/05/2019] [Indexed: 11/28/2022]
Abstract
Among the thioredoxin reductase-type ferredoxin-NAD(P)+ oxidoreductase (FNR) family, FNR from photosynthetic purple non‑sulfur bacterium Rhodopseudomonas palustris (RpFNR) is distinctive because the predicted residue on the re-face of the isoalloxazine ring portion of the FAD prosthetic group is a tyrosine. Here, we report the crystal structure of wild type RpFNR and kinetic analyses of the reaction of wild type, and Y328F, Y328H and Y328S mutants with NADP+/NADPH using steady state and pre-steady state kinetic approaches. The obtained crystal structure of wild type RpFNR confirmed the presence of Tyr328 on the re-face of the isoalloxazine ring of the FAD prosthetic group through the unique hydrogen bonding of its hydroxyl group. In the steady state assays, the substitution results in the decrease of Kd for NADP+ and KM for NADPH in the diaphorase assay; however, the kcat values also decreased significantly. In the stopped-flow spectrophotometry, mixing oxidized RpFNRs with NADPH and reduced RpFNRs with NADP+ resulted in rapid charge transfer complex formation followed by hydride transfer. The observed rate constants for the hydride transfer in both directions were comparable (>400 s-1). The substitution did not drastically affect the rate of hydride transfer, but substantially slowed down the subsequent release and re-association of NADP+/NADPH in both directions. The obtained results suggest that Tyr328 stabilizes the stacking of C-terminal residues on the isoalloxazine ring portion of the FAD prosthetic group, which impedes the access of NADP+/NADPH on the isoalloxazine ring portions, in turn, enhancing the release of the NADP+/NADPH and/or reaction with electron transfer proteins.
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Affiliation(s)
- Daisuke Seo
- Division of Material Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan.
| | - Norifumi Muraki
- Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki 444-8787, Japan; Department of Life Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan; Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Genji Kurisu
- Department of Life Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan; Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan.
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Seo D, Asano T. C-terminal residues of ferredoxin-NAD(P) + reductase from Chlorobaculum tepidum are responsible for reaction dynamics in the hydride transfer and redox equilibria with NADP +/NADPH. PHOTOSYNTHESIS RESEARCH 2018; 136:275-290. [PMID: 29119426 DOI: 10.1007/s11120-017-0462-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 10/27/2017] [Indexed: 06/07/2023]
Abstract
Ferredoxin-NAD(P)+ reductase ([EC 1.18.1.2], [EC 1.18.1.3]) from Chlorobaculum tepidum (CtFNR) is structurally homologous to the bacterial NADPH-thioredoxin reductase (TrxR), but possesses a unique C-terminal extension relative to TrxR that interacts with the isoalloxazine ring moiety of the flavin adenine dinucleotide prosthetic group. In this study, we introduce truncations to the C-terminal residues to examine their role in the reactions of CtFNR with NADP+ and NADPH by spectroscopic and kinetic analyses. The truncation of the residues from Tyr326 to Glu360 (the whole C-terminal extension region), from Phe337 to Glu360 (omitting Phe337 on the re-face of the isoalloxazine ring) and from Ser338 to Glu360 (leaving Phe337 intact) resulted in a blue-shift of the flavin absorption bands. The truncations caused a slight increase in the dissociation constant toward NADP+ and a slight decrease in the Michaelis constant toward NADPH in steady-state assays. Pre-steady-state studies of the redox reaction with NADPH demonstrated that deletions of Tyr326-Glu360 decreased the hydride transfer rate, and the amount of reduced enzyme increased at equilibrium relative to wild-type CtFNR. In contrast, the deletions of Phe337-Glu360 and Ser338-Glu360 resulted in only slight changes in the reaction kinetics and redox equilibrium. These results suggest that the C-terminal region of CtFNR is responsible for the formation and stability of charge-transfer complexes, leading to changes in redox properties and reactivity toward NADP+/NADPH.
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Affiliation(s)
- Daisuke Seo
- Division of Material Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan.
| | - Tomoya Asano
- Division of Functional Genomics, Advanced Science Research Center, Kanazawa University, Takaramachi 13-1, Kanazawa, Ishikawa, 920-0934, Japan
- Wakasa Seikatsu Co. Ltd, 22 Naginataboko-cho, Shijo-Karasuma, Shimogyo-ku, Kyoto, 600-8008, Japan
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Maher A, Staunton K, Kavanagh K. Analysis of the effect of temperature on protein abundance in Demodex-associated Bacillus oleronius. Pathog Dis 2018; 76:4966982. [PMID: 29648591 DOI: 10.1093/femspd/fty032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 04/09/2018] [Indexed: 01/10/2023] Open
Abstract
A potential role for bacteria in the induction of rosacea has been suggested. The aim of this work was to characterise the effect of temperature on the production of immunostimulatory proteins by Bacillus oleronius-a bacterium to which rosacea patients show sera reactivity and which was originally isolated from a Demodex mite from a rosacea patient. The affected skin of rosacea patients is at a higher temperature than unaffected skin, and it was postulated that this might alter the protein expression pattern of B. oleronius. B. oleronius growth was reduced at 37°C compared to 30°C but resulted in increased expression of the immune-reactive 62kDa protein (1.65 fold [P < 0.05]). Proteomic analysis revealed increased abundance of a wide range of proteins involved in the stress response (e.g. stress proteins [21.7-fold increase], phosphocarrier protein HPr [438.5-fold increase], 60 kDa chaperonin [12.6-fold increase]). Proteins decreased in abundance after growth at 37°C included ferredoxin (325-fold decrease) and peptidase (244-fold decrease). This work indicates that the increased skin temperature of rosacea patients may alter the growth and protein production pattern of B. oleronius and lead to the greater production of immuo-stimulatory proteins.
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Affiliation(s)
- Amie Maher
- Department of Biology, Maynooth University, Co. Kildare, Ireland
| | - Kara Staunton
- Department of Biology, Maynooth University, Co. Kildare, Ireland
| | - Kevin Kavanagh
- Department of Biology, Maynooth University, Co. Kildare, Ireland
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Pierella Karlusich JJ, Carrillo N. Evolution of the acceptor side of photosystem I: ferredoxin, flavodoxin, and ferredoxin-NADP + oxidoreductase. PHOTOSYNTHESIS RESEARCH 2017; 134:235-250. [PMID: 28150152 DOI: 10.1007/s11120-017-0338-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/12/2017] [Indexed: 05/21/2023]
Abstract
The development of oxygenic photosynthesis by primordial cyanobacteria ~2.7 billion years ago led to major changes in the components and organization of photosynthetic electron transport to cope with the challenges of an oxygen-enriched atmosphere. We review herein, following the seminal contributions as reported by Jaganathan et al. (Functional genomics and evolution of photosynthetic systems, vol 33, advances in photosynthesis and respiration, Springer, Dordrecht, 2012), how these changes affected carriers and enzymes at the acceptor side of photosystem I (PSI): the electron shuttle ferredoxin (Fd), its isofunctional counterpart flavodoxin (Fld), their redox partner ferredoxin-NADP+ reductase (FNR), and the primary PSI acceptors F x and F A/F B. Protection of the [4Fe-4S] centers of these proteins from oxidative damage was achieved by strengthening binding between the F A/F B polypeptide and the reaction center core containing F x, therefore impairing O2 access to the clusters. Immobilization of F A/F B in the PSI complex led in turn to the recruitment of new soluble electron shuttles. This function was fulfilled by oxygen-insensitive [2Fe-2S] Fd, in which the reactive sulfide atoms of the cluster are shielded from solvent by the polypeptide backbone, and in some algae and cyanobacteria by Fld, which employs a flavin as prosthetic group and is tolerant to oxidants and iron limitation. Tight membrane binding of FNR allowed solid-state electron transfer from PSI bridged by Fd/Fld. Fine tuning of FNR catalytic mechanism led to formidable increases in turnover rates compared with FNRs acting in heterotrophic pathways, favoring Fd/Fld reduction instead of oxygen reduction.
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Affiliation(s)
- Juan José Pierella Karlusich
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Ocampo y Esmeralda, 2000, Rosario, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Ocampo y Esmeralda, 2000, Rosario, Argentina.
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Seo D, Kitashima M, Sakurai T, Inoue K. Kinetics of NADP +/NADPH reduction-oxidation catalyzed by the ferredoxin-NAD(P) + reductase from the green sulfur bacterium Chlorobaculum tepidum. PHOTOSYNTHESIS RESEARCH 2016; 130:479-489. [PMID: 27341807 DOI: 10.1007/s11120-016-0285-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 06/13/2016] [Indexed: 06/06/2023]
Abstract
Ferredoxin-NAD(P)+ oxidoreductase (FNR, [EC 1.18.1.2], [EC 1.18.1.3]) from the green sulfur bacterium Chlorobaculum tepidum (CtFNR) is a homodimeric flavoprotein with significant structural homology to bacterial NADPH-thioredoxin reductases. CtFNR homologs have been found in many bacteria, but only in green sulfur bacteria among photoautotrophs. In this work, we examined the reactions of CtFNR with NADP+, NADPH, and (4S-2H)-NADPD by stopped-flow spectrophotometry. Mixing CtFNRox with NADPH yielded a rapid decrease of the absorbance in flavin band I centered at 460 nm within 1 ms, and then the absorbance further decreased gradually. The magnitude of the decrease increased with increasing NADPH concentration, but even with ~50-fold molar excess NADPH, the absorbance change was only ~45 % of that expected for fully reduced protein. The absorbance in the charge transfer (CT) band centered around 600 nm increased rapidly within 1 ms, then slowly decreased to about 70 % of the maximum. When CtFNRred was mixed with excess NADP+, the absorbance in the flavin band I increased to about 70 % of that of CtFNRox with an apparent rate of ~4 s-1, whereas almost no absorption changes were observed in the CT band. Obtained data suggest that the reaction between CtFNR and NADP+/NADPH is reversible, in accordance with its physiological function.
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Affiliation(s)
- Daisuke Seo
- Division of Material Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan.
| | - Masaharu Kitashima
- Department of Biological Sciences, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa, 259-1293, Japan
- Research Institute for Integrated Science, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa, 259-1293, Japan
| | - Takeshi Sakurai
- Division of Material Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan
| | - Kazuhito Inoue
- Department of Biological Sciences, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa, 259-1293, Japan
- Research Institute for Integrated Science, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa, 259-1293, Japan
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