Redox-Bohr effect in the nine haem cytochrome from Desulfovibrio desulfuricans 27774

Reis, C.; Louro, Ricardo O.; Pacheco, Isabel; Catarino, Teresa; Turner, David L.; Xavier, António V.

doi:10.1016/s0020-1693(02)00951-9

Cited by 11 publications

(9 citation statements)

References 23 publications

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“…5). This observation points to nonequivalence of the redox centers, which is expected for a multiredox center protein with eight heme groups (47,57), as is the case for OmcZ S .…”

Section: Vol 76 2010mentioning

confidence: 69%

Purification and Characterization of OmcZ, an Outer-Surface, Octaheme c -Type Cytochrome Essential for Optimal Current Production by Geobacter sulfurreducens

Inoue

Qian

Morgado

et al. 2010

Appl Environ Microbiol

233

177

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Previous studies have demonstrated that Geobacter sulfurreducens requires the c-type cytochrome OmcZ, which is present in large (OmcZ L ; 50-kDa) and small (OmcZ S ; 30-kDa) forms, for optimal current production in microbial fuel cells. This protein was further characterized to aid in understanding its role in current production. Subcellular-localization studies suggested that OmcZ S was the predominant extracellular form of OmcZ. N-and C-terminal amino acid sequence analysis of purified OmcZ S and molecular weight measurements indicated that OmcZ S is a cleaved product of OmcZ L retaining all 8 hemes, including 1 heme with the unusual c-type heme-binding motif CX 14 CH. The purified OmcZ S was remarkably thermally stable (thermaldenaturing temperature, 94.2°C). Redox titration analysis revealed that the midpoint reduction potential of OmcZ S is approximately ؊220 mV (versus the standard hydrogen electrode [SHE]) with nonequivalent heme groups that cover a large reduction potential range (؊420 to ؊60 mV). OmcZ S transferred electrons in vitro to a diversity of potential extracellular electron acceptors, such as Fe(III) citrate, U(VI), Cr(VI), Au(III), Mn(IV) oxide, and the humic substance analogue anthraquinone-2,6-disulfonate, but not Fe(III) oxide. The biochemical properties and extracellular localization of OmcZ suggest that it is well suited for promoting electron transfer in current-producing biofilms of G. sulfurreducens.

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“…5). This observation points to nonequivalence of the redox centers, which is expected for a multiredox center protein with eight heme groups (47,57), as is the case for OmcZ S .…”

Section: Vol 76 2010mentioning

confidence: 69%

Purification and Characterization of OmcZ, an Outer-Surface, Octaheme c -Type Cytochrome Essential for Optimal Current Production by Geobacter sulfurreducens

Inoue

Qian

Morgado

et al. 2010

Appl Environ Microbiol

233

177

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“…Likewise, destabilization effects of the reduced state were also (25,73) should be present in this cytochrome, playing a considerable role in regulating the heme redox potentials. Indeed, recent work by Reis et al (33) has provided experimental evidence for the presence of the redox-Bohr effect in 9HcA in the physiological pH range. According to our calculations, the redox-Bohr effect allows 9HcA to capture a maximum of 2.4 protons upon full reduction.…”

Section: Table III Midpoint Reduction Potentials Of Individual Hemes mentioning

confidence: 99%

“…According to our calculations, the redox-Bohr effect allows 9HcA to capture a maximum of 2.4 protons upon full reduction. Interestingly, Reis et al (33) proposed two acid-base centers in their thermodynamic interpretation of the experimental data.…”

Section: Table III Midpoint Reduction Potentials Of Individual Hemes mentioning

confidence: 99%

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Redox-Bohr and Other Cooperativity Effects in the Nine-heme Cytochrome c from Desulfovibrio desulfuricans ATCC 27774

Bento

Teixeira

Baptista

et al. 2003

Journal of Biological Chemistry

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The nine-heme cytochrome c is a monomeric multiheme cytochrome found in Desulfovibrio desulfuricans ATCC 27774. The polypeptide chain comprises 296 residues and wraps around nine hemes of type c. It is believed to take part in the periplasmic assembly of proteins involved in the mechanism of hydrogen cycling, receiving electrons from the tetraheme cytochrome c 3 . With the purpose of understanding the molecular basis of electron transfer processes in this cytochrome, we have determined the crystal structures of its oxidized and reduced forms at pH 7.5 and performed theoretical calculations of the binding equilibrium of protons and electrons in these structures. This integrated study allowed us to observe that the reduction process induced relevant conformational changes in several residues, as well as protonation changes in some protonatable residues. In particular, the surroundings of hemes I and IV constitute two areas of special interest. In addition, we were able to ascertain the groups involved in the redoxBohr effect present in this cytochrome and the conformational changes that may underlie the redox-cooperativity effects on different hemes. Furthermore, the thermodynamic simulations provide evidence that the N-and C-terminal domains function in an independent manner, with the hemes belonging to the N-terminal domain showing, in general, a lower redox potential than those found in the C-terminal domain. In this way, electrons captured by the N-terminal domain could easily flow to the C-terminal domain, allowing the former to capture more electrons. A notable exception is heme IX, which has low redox potential and could serve as the exit path for electrons toward other proteins in the electron transfer pathway..

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“…The sensitivity of NMR to the environment of the nuclei gives this technique the required spectral discrimination. NMR has been used to determine the thermodynamic order in which each haem becomes oxidised at different oxidation stages throughout a redox titration (referred in the previous literature as order of oxidation of the haems [13][14][15][16]), as well as to probe in detail the network of redox and redox-Bohr (electron-proton) interactions of the centres of relatively small proteins, up to 16 kDa molecular weight, containing up to four haem groups or two [4Fe-4S] centres [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. However, many proteins and enzymes of physiological interest do not fall in this favourable weight range for NMR studies.…”

Section: Introductionmentioning

confidence: 99%

Redox behaviour of the haem domain of flavocytochrome c₃ from Shewanella frigidimarina probed by NMR

et al. 2004

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Flavocytochrome c 3 from Shewanella frigidimarina (fcc 3 ) is a tetrahaem periplasmic protein of 64 kDa with fumarate reductase activity. This work reports the first example of NMR techniques applied to the assignment of the thermodynamic order of oxidation of the four individual haems for such large protein, expanding its applicability to a wide range of proteins. NMR data from partially and fully oxidised samples of fcc 3 and a mutated protein with an axial ligand of haem IV replaced by alanine were compared with calculated chemical shifts, allowing the structural assignment of the signals and the unequivocal determination of the order of oxidation of the haems. As oxidation progresses the fcc 3 haem domain is polarised, with haems I and II much more oxidised than haems III and IV, haem IV being the most reduced. Thus, during catalysis as an electron is taken by the flavin adenosine dinucleotide from haem IV, haem III is eager to re-reduce haem IV, allowing the transfer of two electrons to the active site.

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Redox-Bohr effect in the nine haem cytochrome from Desulfovibrio desulfuricans 27774

Cited by 11 publications

References 23 publications

Purification and Characterization of OmcZ, an Outer-Surface, Octaheme c -Type Cytochrome Essential for Optimal Current Production by Geobacter sulfurreducens

Purification and Characterization of OmcZ, an Outer-Surface, Octaheme c -Type Cytochrome Essential for Optimal Current Production by Geobacter sulfurreducens

Redox-Bohr and Other Cooperativity Effects in the Nine-heme Cytochrome c from Desulfovibrio desulfuricans ATCC 27774

Redox behaviour of the haem domain of flavocytochrome c₃ from Shewanella frigidimarina probed by NMR

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Redox-Bohr effect in the nine haem cytochrome from Desulfovibrio desulfuricans 27774

Cited by 11 publications

References 23 publications

Purification and Characterization of OmcZ, an Outer-Surface, Octaheme c -Type Cytochrome Essential for Optimal Current Production by Geobacter sulfurreducens

Purification and Characterization of OmcZ, an Outer-Surface, Octaheme c -Type Cytochrome Essential for Optimal Current Production by Geobacter sulfurreducens

Redox-Bohr and Other Cooperativity Effects in the Nine-heme Cytochrome c from Desulfovibrio desulfuricans ATCC 27774

Redox behaviour of the haem domain of flavocytochrome c3 from Shewanella frigidimarina probed by NMR

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Redox behaviour of the haem domain of flavocytochrome c₃ from Shewanella frigidimarina probed by NMR