• 제목/요약/키워드: Ferredoxin

검색결과 47건 처리시간 0.028초

Association of a Common Reductase with Multiple Aromatic Terminal Dioxygenases in Sphingomonas yanoikuyae Strain B1

  • Mihyun Bae;Kim, Eungbin
    • Journal of Microbiology
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    • 제38권1호
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    • pp.40-43
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    • 2000
  • The aromatic dioxygenase system in Sphingomonas yanoikuyae strain Bl consists of three components, an oxygenase, a ferredoxin, and a reductase. The insertional knockout of the bphA4 gene encoding a reductase and subsequent complementation experiments showed that the reductase encoded by bphA4 in S. yanoikuyae strain Bl is associated with multiple dioxygenase components including that of toluate dioxygenase (XyIXY).

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Molecular Characterization of FprB (Ferredoxin-$NADP^+$ Reductase) in Pseudomonas putida KT2440

  • Lee, Yun-Ho;Yeom, Jin-Ki;Kang, Yoon-Suk;Kim, Ju-Hyun;Sung, Jung-Suk;Jeon, Che-Ok;Park, Woo-Jun
    • Journal of Microbiology and Biotechnology
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    • 제17권9호
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    • pp.1504-1512
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    • 2007
  • The fpr gene, which encodes a ferredoxin-$NADP^+$ reductase, is known to participate in the reversible redox reactions between $NADP^+$/NADPH and electron carriers, such as ferredoxin or flavodoxin. The role of Fpr and its regulatory protein, FinR, in Pseudomonas putida KT2440 on the oxidative and osmotic stress responses has already been characterized [Lee at al. (2006). Biochem. Biophys. Res. Commun. 339, 1246-1254]. In the genome of P. putida KT2440, another Fpr homolog (FprB) has a 35.3% amino acid identity with Fpr. The fprB gene was cloned and expressed in Escherichia coli. The diaphorase activity assay was conducted using purified FprB to identify the function of FprB. In contrast to the fpr gene, the induction of fprB was not affected by oxidative stress agents, such as paraquat, menadione, $H_2O_2$, and t-butyl hydroperoxide. However, a higher level of fprB induction was observed under osmotic stress. Targeted disruption of fprB by homologous recombination resulted in a growth defect under high osmotic conditions. Recovery of oxidatively damaged aconitase activity was faster for the fprB mutant than for the fpr mutant, yet still slower than that for the wild type. Therefore, these data suggest that the catalytic function of FprB may have evolved to augment the function of Fpr in P. putida KT2440.

Biochemical characterization of ferredoxin-NADP+ reductase interaction with flavodoxin in Pseudomonas putida

  • Yeom, Jin-Ki;Park, Woo-Jun
    • BMB Reports
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    • 제45권8호
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    • pp.476-481
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    • 2012
  • Flavodoxin (Fld) has been demonstrated to bind to ferredoxin-NADP$^+$ reductase A (FprA) in Pseudomonas putida. Two residues ($Phe^{256}$, $Lys^{259}$) of FprA are likely to be important for interacting with Fld based on homology modeling. Site-directed mutagenesis and pH-dependent enzyme kinetics were performed to further examine the role of these residues. The catalytic efficiencies of FprA-$Ala^{259}$ and FprA-$Asp^{259}$ proteins were two-fold lower than those of the wild-type FprA. Homology modeling also strongly suggested that these two residues are important for electron transfer. Thermodynamic properties such as entropy, enthalpy, and heat capacity changes of FprA-$Ala^{259}$ and FprA-$Asp^{259}$ were examined by isothermal titration calorimetry. We demonstrated, for the first time, that $Phe^{256}$ and $Lys^{259}$ are critical residues for the interaction between FprA and Fld. Van der Waals interactions and hydrogen bonding were also more important than ionic interactions for forming the FprA-Fld complex.

Hydrogenosomal activity of Trichomonas varinalis cultivated under different iron conditions

  • Kim, Yong-Seok;Song, Hyun-Ouk;Choi, Ik-Hwa;Park, Soon-Jung;Ryu, Jae-Sook
    • Parasites, Hosts and Diseases
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    • 제44권4호
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    • pp.373-378
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    • 2006
  • To evaluate whether iron concentration in TYM medium influence on hydrogenosomal enzyme gene expression and hydrogenosomal membrane potential of Trichomonas vaginalis, trophozoites were cultivated in iron-depleted, normal and iron-supplemented TYM media. The mRNA of hydrogenosomal enzymes, such as pyruvate ferredoxin oxidoreductase (PFOR), hydrogenase, ferredoxin and malic enzyme, was increased with iron concentrations in T. vaginalis culture media, measured by RT-PCR. Hydrogenosomal membrane potentials measured with $DiOC_6$ also showed similar tendency, e.g. T. vaginalis cultivated in iron-depleted and iron-supplemented media for 3 days showed a significantly reduced and enhanced hydrogenosomal membrane potential compared with that of normal TYM media, respectively. Therefore, it is suggested that iron may regulate hydrogenosomal activity through hydrogenosomal enzyme expression and hydrogenosomal membrane potential.

NMR Studies on Ferrocytochrome $C_3$ and its Interaction with Ferredoxin I

  • Kim, Andre;Park, Jang-Su
    • 한국자기공명학회논문지
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    • 제3권1호
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    • pp.12-26
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    • 1999
  • The 1H NMR signals of the heme methyl, propionate and related chemical groups of cytochrome C3 from Desulfovibrio vulgaris Miyazaki F (D.v. MF) were assigned by means of 1D NOE, 2D DQFCOSY and 2D TOCSY spectra. They were consistent with the assignments of the hemes with the highest and second-lowest redox potentials reported by Gayda et al. [Reference: 15]. The heme assignments were also supported by NOE between the methyl groups of these hemes and the side chain of Val-18, All the results contradicted the heme assignments for D.v. MF cytochrome C3 made on the basis of NMR [Reference: 11]. Based on these assignments, the interaction of cytochrome C3 with ferredoxin I was investigated by NMR. The major interaction site of cytochrome C3 was identified as the heme with the highest redox potential, which is surrounded by the highest density of positive charges. The stoichiometry and association constant were two cytochrome C3 molecules per monomer of ferredoxin I and 108 M-2 (at 53 mM ionic strength and $25^{\circ}C$), respectively.

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Isolation and Partial Characterization of Two Ferredoxins from the Photosynthetic Bacterium Heliobacillus mobilis

  • Hatano, Atsushi;Inoue, Kazuhito;Deo, Daisuke;Sakurai, Hidehiro
    • Journal of Photoscience
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    • 제9권2호
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    • pp.388-390
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    • 2002
  • Two ferredoxin (Fd) fractions, namely, Fd-A and Fd-B were isolated from Heliobacillus mobilis cells, and purified by ammonium sulfate fractionation, DEAE, gel-permeation and Phenyl-Superose column chromatographies under anaerobic conditions. Their absorption spectra were typical of 2[4Fe-4S] cluster type Fds with peaks at about 385 and 280 nm and a shoulder at about 305 nm. Their N-terminal amino acid sequences were determined, which showed that both of them contain a [4Fe-4S] cluster binding motif. Fd-B was sensitive to oxygen, and itsA$_{385}$ value decreased by about 50% in 2 h at 4$^{\circ}C$ under aerobic conditions. In contrast, $A_{385}$ of Fd-A was essentially unchanged up to 24 h under the same conditions.

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Involvement of Electrostatic Interactions between the Components of Toluene Dioxygenase from Pseudomonas putida Fl

  • Lee, Kyoung
    • Journal of Microbiology and Biotechnology
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    • 제8권4호
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    • pp.416-421
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    • 1998
  • A carboxyl group modifier, l-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) was used to study the interactions between three components of toluene dioxygenase (TDO) from Pseudomonas putida FI. $Ferredoxin_{TOL}$ activity was increased by the treatment with EDC; however, the activity was rapidly declined in the prolonged incubation. In covalent cross-linking experiments with EDC, $Ferredoxin_{TOL}$ made a one-to-one complex with $Reductase_{TOL}$ or the large subunit of $ISP_{TOL}$. These results provide evidence for the involvement of electrostatic interactions in the TDO electron transfer system.

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방선균 시토크롬 P450와 전자전이시스템 (Streptomyces Cytochrome P450 and Electron Transport System)

  • 송재경;오태진
    • 한국미생물·생명공학회지
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    • 제38권3호
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    • pp.227-234
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    • 2010
  • Cytochrome P450 enzymes which require the supply of electrons from NAD(P)H have a great biotechnological impact as they catalyze valuable reactions on a vast variety of substrates. However, very limited biotechnological application has been reported so far due to their functional complexity, limited stability (instability) and, in most cases, low catalytic activity. In this present review, we introduce some possibilities for improving their defect by exploring electron transport system and substrate flexibility in field of Streptomyces cytochrome P450.