TY - JOUR
T1 - Succinate as donor; Fumarate as acceptor
AU - Tomasiak, Thomas M.
AU - Cecchini, Gary
AU - Iverson, Tina M.
N1 - Funding Information:
Studies in our laboratories were supported by the Department of Veterans Affairs (G.C.) and by National Institutes of Health Grants GM61606 (to G.C.) and GM079419 (to T.M.I.), a pilot award funded by P30 ES000267 (to T.M.I.), and the Ellison Medical Foundation AGNS- 0325 (T.M.I.). No potential conflicts of interest relevant to this review were reported.
Publisher Copyright:
© 2013 American Society for Microbiology.
PY - 2007
Y1 - 2007
N2 - Succinate and fumarate are four-carbon dicarboxylates that differ in the identity of their central bond (single or double). The oxidoreduction of these small molecules plays a central role in both aerobic and anaerobic respiration. During aerobic respiration, succinate is oxidized, donating two reducing equivalents, while in anaerobic respiration, fumarate is reduced, accepting two reducing equivalents. Two related integral membrane Complex II superfamily members catalyze these reactions, succinate:ubiquinone oxidoreductase (SQR) and fumarate:menaquinol oxidoreductase (QFR). The structure, function, and regulation of these integral-membrane enzymes are summarized here. The overall architecture of these Complex II enzymes has been found to consist of four subunits: two integral membrane subunits, and a soluble domain consisting of an iron-sulfur protein subunit, and a flavoprotein subunit. This architecture provides a scaffold that houses one active site in the membrane and another in the soluble milieu, making a linear electron transfer chain that facilities shuttling of reducing equivalents between the two active sites. A combination of kinetic measurements, mutagenesis, electron paramagnetic resonance spectroscopy, UV/Vis spectroscopy, and x-ray crystallography have suggested mechanisms for succinate:fumarate interconversion, electron transfer, and quinone:quinol interconversion. Of particular interest are the structural details that control directionality and make SQR and QFR primed for preferential catalysis each in different favored directions.
AB - Succinate and fumarate are four-carbon dicarboxylates that differ in the identity of their central bond (single or double). The oxidoreduction of these small molecules plays a central role in both aerobic and anaerobic respiration. During aerobic respiration, succinate is oxidized, donating two reducing equivalents, while in anaerobic respiration, fumarate is reduced, accepting two reducing equivalents. Two related integral membrane Complex II superfamily members catalyze these reactions, succinate:ubiquinone oxidoreductase (SQR) and fumarate:menaquinol oxidoreductase (QFR). The structure, function, and regulation of these integral-membrane enzymes are summarized here. The overall architecture of these Complex II enzymes has been found to consist of four subunits: two integral membrane subunits, and a soluble domain consisting of an iron-sulfur protein subunit, and a flavoprotein subunit. This architecture provides a scaffold that houses one active site in the membrane and another in the soluble milieu, making a linear electron transfer chain that facilities shuttling of reducing equivalents between the two active sites. A combination of kinetic measurements, mutagenesis, electron paramagnetic resonance spectroscopy, UV/Vis spectroscopy, and x-ray crystallography have suggested mechanisms for succinate:fumarate interconversion, electron transfer, and quinone:quinol interconversion. Of particular interest are the structural details that control directionality and make SQR and QFR primed for preferential catalysis each in different favored directions.
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U2 - 10.1128/ecosal.3.2.6
DO - 10.1128/ecosal.3.2.6
M3 - Article
AN - SCOPUS:84959059927
SN - 2324-6200
VL - 2
JO - EcoSal Plus
JF - EcoSal Plus
IS - 2
ER -