Electron transfer flavoprotein and its role in mitochondrial energy metabolism in health and disease

Abstract Basal expression of the P2X7 receptor (P2X7R) improves mitochondrial metabolism, ATP synthesis and overall fitness of immune and non-immune cells. We investigated P2X7R contribution to energy metabolism and subcellular localization in fibroblasts (mouse embryo fibroblasts and HEK293 human fibroblasts), mouse microglia (primary brain microglia and the N13 microglia cell line), and heart tissue. The P2X7R localizes to mitochondria, and its lack a) decreases basal respiratory rate, ATP-coupled respiration, maximal uncoupled respiration, resting mitochondrial potential, mitochondrial matrix Ca2+ level, b) modifies expression pattern of oxidative phosphorylation (OxPhos) enzymes, and c) severely affects cardiac performance. Hearts from P2rx7-deleted versus WT mice are larger, heart mitochondria smaller, and stroke volume (SV), ejection fraction (EF), fractional shortening (FS) and cardiac output (CO), are significantly decreased. Accordingly, physical fitness of P2X7R-null mice is severely reduced. Thus, the P2X7R is a key modulator of mitochondrial energy metabolism and a determinant of physical fitness.

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Developmental, nutritional, and hormonal regulation of tissue-specific expression of the genes encoding various acyl-CoA dehydrogenases and alpha-subunit of electron transfer flavoprotein in rat.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(20)80500-6 ◽

1993 ◽

Vol 268 (32) ◽

pp. 24114-24124

Author(s):

M Nagao ◽

B Parimoo ◽

K Tanaka

Keyword(s):

Electron Transfer ◽

Hormonal Regulation ◽

Alpha Subunit ◽

Specific Expression ◽

Tissue Specific ◽

Electron Transfer Flavoprotein ◽

Tissue Specific Expression ◽

Genes Encoding ◽

Acyl Coa Dehydrogenases

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Cloning, sequence analysis, and expression of the genes encoding the two subunits of the methylotrophic bacterium W3A1 electron transfer flavoprotein.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)31609-0 ◽

1994 ◽

Vol 269 (51) ◽

pp. 32120-32130

Author(s):

D Chen ◽

R P Swenson

Keyword(s):

Electron Transfer ◽

Sequence Analysis ◽

Methylotrophic Bacterium ◽

Electron Transfer Flavoprotein ◽

Genes Encoding

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Spectroscopic evidence for direct flavin-flavin contact in a bifurcating electron transfer flavoprotein

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.013174 ◽

2020 ◽

Vol 295 (36) ◽

pp. 12618-12634

Author(s):

H. Diessel Duan ◽

Nishya Mohamed-Raseek ◽

Anne-Frances Miller

Keyword(s):

Electron Transfer ◽

Density Functional ◽

Protein Denaturation ◽

Rhodopseudomonas Palustris ◽

Density Functional Theory Calculations ◽

Site Directed Mutagenesis ◽

Functional Theory ◽

Electron Transfer Flavoprotein ◽

Midpoint Potential ◽

Ct Complex

A remarkable charge transfer (CT) band is described in the bifurcating electron transfer flavoprotein (Bf-ETF) from Rhodopseudomonas palustris (RpaETF). RpaETF contains two FADs that play contrasting roles in electron bifurcation. The Bf-FAD accepts electrons pairwise from NADH, directs one to a lower-reduction midpoint potential (E°) carrier, and the other to the higher-E° electron transfer FAD (ET-FAD). Previous work noted that a CT band at 726 nm formed when ET-FAD was reduced and Bf-FAD was oxidized, suggesting that both flavins participate. However, existing crystal structures place them too far apart to interact directly. We present biochemical experiments addressing this conundrum and elucidating the nature of this CT species. We observed that RpaETF missing either FAD lacked the 726 nm band. Site-directed mutagenesis near either FAD produced altered yields of the CT species, supporting involvement of both flavins. The residue substitutions did not alter the absorption maximum of the signal, ruling out contributions from residue orbitals. Instead, we propose that the residue identities modulate the population of a protein conformation that brings the ET-flavin and Bf-flavin into direct contact, explaining the 726 nm band based on a CT complex of reduced ET-FAD and oxidized Bf-FAD. This is corroborated by persistence of the 726 nm species during gentle protein denaturation and simple density functional theory calculations of flavin dimers. Although such a CT complex has been demonstrated for free flavins, this is the first observation of such, to our knowledge, in an enzyme. Thus, Bf-ETFs may optimize electron transfer efficiency by enabling direct flavin-flavin contact.

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Cross-linking of the electron-transfer flavoprotein to electron-transfer flavoprotein-ubiquinone oxidoreductase with heterobifunctional reagents

Biochemical Journal ◽

10.1042/bj2550869 ◽

1988 ◽

Vol 255 (3) ◽

pp. 869-876 ◽

Cited By ~ 14

Author(s):

D J Steenkamp

Keyword(s):

Electron Transfer ◽

Small Subunit ◽

Cross Linking ◽

Minor Effect ◽

Electron Transfer Flavoprotein ◽

Ubiquinone Oxidoreductase ◽

Lysine Residues ◽

Cross Links ◽

A Minor ◽

Chemical Cross Linking

The mitochondrial electron-transfer flavoprotein (ETF) is a heterodimer containing only one FAD. In previous work on the structure-function relationships of ETF, its interaction with the general acyl-CoA dehydrogenase (GAD) was studied by chemical cross-linking with heterobifunctional reagents [D. J. Steenkamp (1987) Biochem. J. 243, 519-524]. GAD whose lysine residues were substituted with 3-(2-pyridyldithio)propionyl groups was preferentially cross-linked to the small subunit of ETF, the lysine residues of which had been substituted with 4-mercaptobutyramidine (MBA) groups. This work was extended to the interaction of ETF with ETF-ubiquinone oxidoreductase (ETF-Q ox). ETF-Q ox was partially inactivated by modification with N-succinimidyl 3-(2-pyridyldithio)propionate to introduce pyridyl disulphide structures. A similar modification of ETF caused a large increase in the apparent Michaelis constant of ETF-Q ox for modified ETF owing to the loss of positive charge on some critical lysines of ETF. When ETF-Q ox was modified with 2-iminothiolane to introduce 4-mercaptobutyramidine groups, only a minor effect on the activity of the enzyme was observed. To retain the positive charges on the lysine residues of ETF, pyridyl disulphide structures were introduced by treating ETF with 2-iminothiolane in the presence of 2,2′-dithiodipyridyl. The electron-transfer activity of the resultant ETF preparation containing 4-(2-pyridyldithio)butyramidine (PDBA) groups was only slightly affected. When ETF-Q ox substituted with MBA groups was mixed with ETF bearing PDBA groups, at least 70% of the cross-links formed between the two proteins were between the small subunit of ETF and ETF-Q ox. ETF-Q ox, therefore, interacts predominantly with the same subunit of ETF as GAD. Variables which affect the selectivity of ETF-Q ox cross-linking to the subunits of ETF are considered.

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Protective effects of lipoic acid against acrylamide-induced neurotoxicity: involvement of mitochondrial energy metabolism and autophagy

Food & Function ◽

10.1039/c7fo01429e ◽

2017 ◽

Vol 8 (12) ◽

pp. 4657-4667 ◽

Cited By ~ 11

Author(s):

Ge Song ◽

Zhigang Liu ◽

Luanfeng Wang ◽

Renjie Shi ◽

Chuanqi Chu ◽

...

Keyword(s):

Energy Metabolism ◽

Lipoic Acid ◽

Redox Status ◽

Protective Effects ◽

Mitochondrial Energy Metabolism

Lipoic acid (LA) suppressed acrylamide (ACR)-induced inflammation, redox status disturbance, autophagy, and apoptosis mediated by mitochondria in the SH-SY5Y cells.

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