The oxidant‐responsive diaphorase of <i>Rhodobacter capsulatus</i> is a ferredoxin (flavodoxin)‐NADP(H) reductase

Bittel, Cristian; Tabares, Leandro C.; Armesto, Martín S.; Carrillo, Néstor; Cortez, Néstor

doi:10.1016/s0014-5793(03)01075-5

Cited by 20 publications

(38 citation statements)

References 39 publications

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“…The CD spectra of Xac -FNR displayed the same spectral trend that was observed for subclass I bacterial FNR from Rhodobacter capsulatus (Figure 4B) [32] except in the near UV region. Previous studies have demonstrated that this CD spectral region is susceptible to the polarity of the solvent [33].…”

Section: Resultssupporting

confidence: 70%

“…In contrast, various redox compounds, including complexed metals and aromatic molecules, can operate as mono and bi-electronic acceptors in vitro , in the so-called diaphorase reaction [39]. Xac -FNR showed higher NADPH-diaphorase activity compared to R. capsulatus FNR (121.9 s- 1 vs. 7.2 s −1 , Table 1 and [32]) and Ec -FNR (Table 1). In addition, Xac -FNR showed higher NADH-diaphorase activity than Ec -FNR (Table 1).…”

Section: Resultsmentioning

confidence: 99%

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Structural-Functional Characterization and Physiological Significance of Ferredoxin-NADP+ Reductase from Xanthomonas axonopodis pv. citri

et al. 2011

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Xanthomonas axonopodis pv. citri is a phytopathogen bacterium that causes severe citrus canker disease. Similar to other phytopathogens, after infection by this bacterium, plants trigger a defense mechanism that produces reactive oxygen species. Ferredoxin-NADP+ reductases (FNRs) are redox flavoenzymes that participate in several metabolic functions, including the response to reactive oxygen species. Xanthomonas axonopodis pv. citri has a gene (fpr) that encodes for a FNR (Xac-FNR) that belongs to the subclass I bacterial FNRs. The aim of this work was to search for the physiological role of this enzyme and to characterize its structural and functional properties. The functionality of Xac-FNR was tested by cross-complementation of a FNR knockout Escherichia coli strain, which exhibit high susceptibility to agents that produce an abnormal accumulation of •O2 -. Xac-FNR was able to substitute for the FNR in E. coli in its antioxidant role. The expression of fpr in X. axonopodis pv. citri was assessed using semiquantitative RT-PCR and Western blot analysis. A 2.2-fold induction was observed in the presence of the superoxide-generating agents methyl viologen and 2,3-dimethoxy-1,4-naphthoquinone. Structural and functional studies showed that Xac-FNR displayed different functional features from other subclass I bacterial FNRs. Our analyses suggest that these differences may be due to the unusual carboxy-terminal region. We propose a further classification of subclass I bacterial FNRs, which is useful to determine the nature of their ferredoxin redox partners. Using sequence analysis, we identified a ferredoxin (XAC1762) as a potential substrate of Xac-FNR. The purified ferredoxin protein displayed the typical broad UV-visible spectrum of [4Fe-4S] clusters and was able to function as substrate of Xac-FNR in the cytochrome c reductase activity. Our results suggest that Xac-FNR is involved in the oxidative stress response of Xanthomonas axonopodis pv. citri and performs its biological function most likely through the interaction with ferredoxin XAC1762.

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Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Structural-Functional Characterization and Physiological Significance of Ferredoxin-NADP+ Reductase from Xanthomonas axonopodis pv. citri

et al. 2011

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“…Moreover, redox potential values of Rc -NifF are in the same range as those reported for the iron-sulphur protein component of nitrogenase [2]. In R. capsulatus , nitrogenase reduction by NifF has been proposed to be supported by ferredoxin(flavodoxin)-NADP(H) reductase (FPR, EC 1.18.1.2) [12]. FPR displays turnover values compatible with those of the nitrogenase and would act by transferring electrons from the cellular NADPH pool to the nitrogenase via Rc -NifF [2].…”

Section: Introductionmentioning

confidence: 70%

“…In this regard, evidence reported so far support that this biological meaning is related with the interaction of nif Flds with other nif proteins. In the case of Rc -NifF, those proteins would be the nitrogenase and its proposed natural electron donor, the flavodoxin:NADP(H) reductase [12]. …”

Section: Resultsmentioning

confidence: 99%

Structural and Phylogenetic Analysis of Rhodobacter capsulatus NifF: Uncovering General Features of Nitrogen-fixation (nif)-Flavodoxins

Pérez‐Dorado

Bortolotti

Cortez

et al. 2013

IJMS

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Analysis of the crystal structure of NifF from Rhodobacter capsulatus and its homologues reported so far reflects the existence of unique structural features in nif flavodoxins: a leucine at the re face of the isoalloxazine, an eight-residue insertion at the C-terminus of the 50’s loop and a remarkable difference in the electrostatic potential surface with respect to non-nif flavodoxins. A phylogenetic study on 64 sequences from 52 bacterial species revealed four clusters, including different functional prototypes, correlating the previously defined as “short-chain” with the firmicutes flavodoxins and the “long-chain” with gram-negative species. The comparison of Rhodobacter NifF structure with other bacterial flavodoxin prototypes discloses the concurrence of specific features of these functional electron donors to nitrogenase.

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“…Interestingly, homologs of this reductase have been shown to participate in concerted antioxidant responses in many different heterotrophic organisms, including bacteria (Bianchi et al, 1995;Yannone and Burgess, 2001;Krapp et al, 2002;Bittel et al, 2003), yeast (Saccharomyces cerevisiae; Li et al, 2001), and protozoa (Girardini et al, 2003), suggesting that it might play a general role in protection against oxidants. We have recently shown that the FNR of E. coli provides low potential electrons for repair processes, especially for reductive healing of FeS centers inactivated by superoxide (Giró et al, 2006).…”

Section: Photosynthesis In Fnr-mentioning

confidence: 99%

Transgenic Tobacco Plants Overexpressing Chloroplastic Ferredoxin-NADP(H) Reductase Display Normal Rates of Photosynthesis and Increased Tolerance to Oxidative Stress

et al. 2006

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(M.P., H.T., M.-R.H.)Ferredoxin-NADP(H) reductase (FNR) catalyzes the last step of photosynthetic electron transport in chloroplasts, driving electrons from reduced ferredoxin to NADP 1 . This reaction is rate limiting for photosynthesis under a wide range of illumination conditions, as revealed by analysis of plants transformed with an antisense version of the FNR gene. To investigate whether accumulation of this flavoprotein over wild-type levels could improve photosynthetic efficiency and growth, we generated transgenic tobacco (Nicotiana tabacum) plants expressing a pea (Pisum sativum) FNR targeted to chloroplasts. The alien product distributed between the thylakoid membranes and the chloroplast stroma. Transformants grown at 150 or 700 mmol quanta m 22 s 21 displayed wild-type phenotypes regardless of FNR content. Thylakoids isolated from plants with a 5-fold FNR increase over the wild type displayed only moderate stimulation (approximately 20%) in the rates of electron transport from water to NADP 1 . In contrast, when donors of photosystem I were used to drive NADP 1 photoreduction, the activity was 3-to 4-fold higher than the wild-type controls. Plants expressing various levels of FNR (from 1-to 3.6-fold over the wild type) failed to show significant differences in CO 2 assimilation rates when assayed over a range of light intensities and CO 2 concentrations. Transgenic lines exhibited enhanced tolerance to photooxidative damage and redox-cycling herbicides that propagate reactive oxygen species. The results suggest that photosynthetic electron transport has several rate-limiting steps, with FNR catalyzing just one of them.

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The oxidant‐responsive diaphorase of Rhodobacter capsulatus is a ferredoxin (flavodoxin)‐NADP(H) reductase

Cited by 20 publications

References 39 publications

Structural-Functional Characterization and Physiological Significance of Ferredoxin-NADP+ Reductase from Xanthomonas axonopodis pv. citri

Structural-Functional Characterization and Physiological Significance of Ferredoxin-NADP+ Reductase from Xanthomonas axonopodis pv. citri

Structural and Phylogenetic Analysis of Rhodobacter capsulatus NifF: Uncovering General Features of Nitrogen-fixation (nif)-Flavodoxins

Transgenic Tobacco Plants Overexpressing Chloroplastic Ferredoxin-NADP(H) Reductase Display Normal Rates of Photosynthesis and Increased Tolerance to Oxidative Stress

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