Classification of fumarate reductases and succinate dehydrogenases based upon their contrasting behaviour in the reduced benzylviologen/fumarate assay

Ackrell, Brian A.C.; Armstrong, Fräser A.; Cochran, Bruce; Sucheta, Artur; Chen, Yu

doi:10.1016/0014-5793(93)81768-u

Cited by 37 publications

(39 citation statements)

References 11 publications

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“…Comparison of available structures of complex II type enzymes (9 -16) does not provide an obvious suggestion for the importance of a negative charge or polar group at this position. One of the prominent differences between SQR and QFR, known as a tunnel diode effect, was observed in several SQR but not QFR enzymes and has been associated with the FAD site of the proteins (21)(22)(23)(24). We anticipated that the Glu/Gln residue ϳ5 Å from the FAD redox center may contribute to the tunnel diode phenomenology.…”

Section: Change In Catalytic Efficiency Of the Sqr And Qfr Mutant Enzmentioning

confidence: 99%

“…In these studies, SQR is proficient at reducing fumarate above an electrode potential of approximately Ϫ60 mV (pH 7.0), whereas catalysis is severely constrained at potentials below this value (21,22). This electrochemical property of succinate dehydrogenase has been described as being analogous to that of a tunnel diode, which is a device displaying negative resistance in a certain potential region (21,22). Native QFRs by contrast, exhibit normal positive order kinetics (i.e.…”

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confidence: 99%

“…In addition to conventional steady-state solution kinetics, these differences have been measured by electro-chemical experiments (protein film voltammetry) in which the enzymes exhibit high electrocatalytic activity when adsorbed on a graphite electrode. In these studies, SQR is proficient at reducing fumarate above an electrode potential of approximately Ϫ60 mV (pH 7.0), whereas catalysis is severely constrained at potentials below this value (21,22). This electrochemical property of succinate dehydrogenase has been described as being analogous to that of a tunnel diode, which is a device displaying negative resistance in a certain potential region (21,22).…”

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Fumarate Reductase and Succinate Oxidase Activity of Escherichia coli Complex II Homologs Are Perturbed Differently by Mutation of the Flavin Binding Domain

Maklashina

Iverson

Sher

et al. 2006

Journal of Biological Chemistry

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The Escherichia coli complex II homologues succinate:ubiquinone oxidoreductase (SQR, SdhCDAB) and menaquinol:fumarate oxidoreductase (QFR, FrdABCD) have remarkable structural homology at their dicarboxylate binding sites. Although both SQR and QFR can catalyze the interconversion of fumarate and succinate, QFR is a much better fumarate reductase, and SQR is a better succinate oxidase. An exception to the conservation of amino acids near the dicarboxylate binding sites of the two enzymes is that there is a Glu (FrdA Glu-49) near the covalently bound FAD cofactor in most QFRs, which is replaced with a Gln (SdhA Gln-50) in SQRs. The role of the amino acid side chain in enzymes with Glu/Gln/Ala substitutions at FrdA Glu-49 and SdhA Gln-50 has been investigated in this study. The data demonstrate that the mutant enzymes with Ala substitutions in either QFR or SQR remain functionally similar to their wild type counterparts. There were, however, dramatic changes in the catalytic properties when Glu and Gln were exchanged for each other in QFR and SQR. The data show that QFR and SQR enzymes are more efficient succinate oxidases when Gln is in the target position and a better fumarate reductase when Glu is present. Overall, structural and catalytic analyses of the FrdA E49Q and SdhA Q50E mutants suggest that coulombic effects and the electronic state of the FAD are critical in dictating the preferred directionality of the succinate/fumarate interconversions catalyzed by the complex II superfamily. . The membrane-extrinsic domain is bound to the membrane through interactions with the hydrophobic subunits of the complex. These subunits comprise two membrane anchor polypeptides, each containing three transmembrane helices and providing a binding site(s) for quinone (for reviews, see Refs. 5-8). In addition, the E. coli SQR hydrophobic peptides bind one b-type heme, whereas the E. coli QFR lacks heme.Comparison of the structures of complex II is possible due to the availability of x-ray crystallographic structures for both SQR and QFR of E. coli (9, 10), the porcine SQR (11), the QFR from Wolinella succinogenes (12), and soluble homologs of the flavoprotein subunit that function as periplasmically localized fumarate reductases (13-16). The flavoprotein subunits from the E. coli SQR and QFR are highly homologous, with 64% similarity and 44% identity of amino acid residues (3). The sequence similarity within the SQR/QFR superfamily is reflected in structural alignments of members whose structures are known (17)(18)(19). Within this group, the backbone C ␣ atoms can be superimposed with a maximal root mean square deviation of 1.5 Å (10). A detailed hydride transfer mechanism for fumarate reduction has been proposed based on structural data and enzyme assays of wild type and mutant enzymes (15, 18 -20). QFRs and SQRs all contain covalently bound FAD and are bidirectional (i.e. they will catalyze both succinate oxidation and fumarate reduction). There are, however, significant differences for the kinetics of fumarate reduction by...

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Section: Change In Catalytic Efficiency Of the Sqr And Qfr Mutant Enzmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Fumarate Reductase and Succinate Oxidase Activity of Escherichia coli Complex II Homologs Are Perturbed Differently by Mutation of the Flavin Binding Domain

Maklashina

Iverson

Sher

et al. 2006

Journal of Biological Chemistry

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“…This build-up of ubiquinol and fumarate would have favoured the functioning of CII in reverse as a fumarate reductase, to regenerate ubiquinone. This scenario is plausible, as some CIIs of aerobes perform fumarate reduction with sufficient concentrations of substrate [142]. Metabolically, this organelle would resemble the mitochondria of some animals (e.g.…”

Section: (C) a New Scenariomentioning

confidence: 99%

Diversity and origins of anaerobic metabolism in mitochondria and related organelles

Stairs

Leger

Roger

2015

Phil. Trans. R. Soc. B

131

172

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One contribution of 17 to a theme issue 'Eukaryotic origins: progress and challenges'. Across the diversity of life, organisms have evolved different strategies to thrive in hypoxic environments, and microbial eukaryotes ( protists) are no exception. Protists that experience hypoxia often possess metabolically distinct mitochondria called mitochondrion-related organelles (MROs). While there are some common metabolic features shared between the MROs of distantly related protists, these organelles have evolved independently multiple times across the breadth of eukaryotic diversity. Until recently, much of our knowledge regarding the metabolic potential of different MROs was limited to studies in parasitic lineages. Over the past decade, deep-sequencing studies of free-living anaerobic protists have revealed novel configurations of metabolic pathways that have been co-opted for life in low oxygen environments. Here, we provide recent examples of anaerobic metabolism in the MROs of free-living protists and their parasitic relatives. Additionally, we outline evolutionary scenarios to explain the origins of these anaerobic pathways in eukaryotes.

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“…Open reading frames expected to code for polypeptides with significant amino acid sequence identity to the FeS-containing B-subunit of SDH or FRD (SdhB or FrdB), sll1625 and sll0823, were identified from the genome sequence (13). It is not possible from the sequence alone to discern whether a gene codes for a subunit of an SDH type or of an FRD type of succinate:quinol oxidoreductase (1). In this study, the expression of sll1625 and sll0823 and the function of their gene products in thylakoid electron transport and in the central organic acid metabolism of the cyanobacterium were investigated.…”

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Succinate:Quinol Oxidoreductases in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Presence and Function in Metabolism and Electron Transport

2000

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The open reading frames sll1625 and sll0823, which have significant sequence similarity to genes coding for the FeS subunits of succinate dehydrogenase and fumarate reductase, were deleted singly and in combination in the cyanobacterium Synechocystis sp. strain PCC 6803. When the organic acid content in the ⌬sll1625 and ⌬sll0823 strains was analyzed, a 100-fold decrease in succinate and fumarate concentrations was observed relative to the wild type. A similar analysis for the ⌬sll1625 ⌬sll0823 strain revealed that 17% of the wild-type succinate levels remained, while only 1 to 2% of the wild-type fumarate levels were present. Addition of 2-oxoglutarate to the growth media of the double mutant strain prior to analysis of organic acids in cells caused succinate to accumulate. This indicates that succinate dehydrogenase activity had been blocked by the deletions and that 2-oxoglutarate can be converted to succinate in vivo in this organism, even though a traditional 2-oxoglutarate dehydrogenase is lacking. In addition, reduction of the thylakoid plastoquinone pool in darkness in the presence of KCN was up to fivefold slower in the mutants than in the wild type. Moreover, in vitro succinate dehydrogenase activity observed in wild-type membranes is absent from those isolated from the double mutant and reduced in those from the single mutants, further indicating that the sll1625 and sll0823 open reading frames encode subunits of succinate dehydrogenase complexes that are active in the thylakoid membrane of the cyanobacterium.

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Classification of fumarate reductases and succinate dehydrogenases based upon their contrasting behaviour in the reduced benzylviologen/fumarate assay

Cited by 37 publications

References 11 publications

Fumarate Reductase and Succinate Oxidase Activity of Escherichia coli Complex II Homologs Are Perturbed Differently by Mutation of the Flavin Binding Domain

Fumarate Reductase and Succinate Oxidase Activity of Escherichia coli Complex II Homologs Are Perturbed Differently by Mutation of the Flavin Binding Domain

Diversity and origins of anaerobic metabolism in mitochondria and related organelles

Succinate:Quinol Oxidoreductases in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Presence and Function in Metabolism and Electron Transport

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