Cloned (Comment) | Organism |
---|---|
recombinant expression of His-tagged wild-type and mutant enzymes in Escherichia coli strain Rosetta (DE3) pLysS | Cereibacter sphaeroides |
Protein Variants | Comment | Organism |
---|---|---|
E377N | site-directed mutagenesis, the mutant does not show increased oxidase activity although reduced dehydrogenase activity compared to wild-type | Cereibacter sphaeroides |
M375S | site-directed mutagenesis, the mutant is inactive as oxidase | Cereibacter sphaeroides |
additional information | (2S)-methylsuccinyl-CoA dehydrogenase is engineered towards oxidase activity by rational mutagenesis. The molecular base for dioxygen reactivity in the engineered oxidase shows that the increased oxidase function of the engineered enzyme comes at a decreased dehydrogenase activity, analysis by using stopped-flow UV-spectroscopy and liquid chromatography-mass spectrometry (LC-MS) based assays. Simply increasing accessibility for dioxygen is not a straight-forward approach to increase the oxidase reactivity in ACADs. Of three single mutants W315F, T317G and E377N only the Mcd variant T317G shows significant oxidase activity. Combination of all three mutations results in a variant with considerable oxidase activity. The three residues (Y372, M375, and Y378) as targets are located in the vicinity of the FAD cofactor. M375 and Y372 cover the isoalloxazine moiety of the FAD to shield it from solvent exposure. An increased solvation of the active site is proposed to increase reactivity towards dioxygen in ACADs due to stabilization of the formed superoxide. Mutation of Y372 and M375 to isoleucine and serine, respectively, is performed because these smaller residues are partially conserved in other ACADs, according to a multiple sequence alignment | Cereibacter sphaeroides |
T317G | site-directed mutagenesis, the mutant shows increased oxidase activity and reduced dehydrogenase activity compared to wild-type. The mutant directly reacts with O2 | Cereibacter sphaeroides |
W315F | site-directed mutagenesis, the mutant does not show increased oxidase activity although reduced dehydrogenase activity compared to wild-type | Cereibacter sphaeroides |
W315F/T317G/E377N | site-directed mutagenesis, the mutant shows increased oxidase activity and reduced dehydrogenase activity compared to wild-type. The mutant directly reacts with O2 | Cereibacter sphaeroides |
Y372I | site-directed mutagenesis, the mutant is inactive as oxidase | Cereibacter sphaeroides |
Y378G | site-directed mutagenesis, the mutant is inactive as oxidase | Cereibacter sphaeroides |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
(2S)-methylsuccinyl-CoA + electron-transfer flavoprotein | Cereibacter sphaeroides | - |
2-methylfumaryl-CoA + reduced electron-transfer flavoprotein | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Cereibacter sphaeroides | D3JV03 | Rhodobacter sphaeroides | - |
Purification (Comment) | Organism |
---|---|
recombinant His-tagged wild-type and mutant enzymes from Escherichia coli strain Rosetta (DE3) pLysS by nickel affinity chromatography and ultrafiltration | Cereibacter sphaeroides |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
(2S)-methylsuccinyl-CoA + electron-transfer flavoprotein | - |
Cereibacter sphaeroides | 2-methylfumaryl-CoA + reduced electron-transfer flavoprotein | - |
? | |
additional information | FAD does not dissociate from the enzyme during catalysis. The reaction product can only be released after FAD is re-oxidized within the active site by a final electron acceptor | Cereibacter sphaeroides | ? | - |
- |
Synonyms | Comment | Organism |
---|---|---|
MCD | - |
Cereibacter sphaeroides |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | 30 | assay at | Cereibacter sphaeroides |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7.8 | - |
assay at | Cereibacter sphaeroides |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
electron transferring flavoprotein | ETF, recombinant EtfA and EtfB from Rhodobacter sphaeroides by expression in Escherichia coli strain BL21(DE3) | Cereibacter sphaeroides | |
FAD | required prosthetic group, FAD does not dissociate from the enzyme during catalysis. The reaction product can only be released after FAD is re-oxidized within the active site by a final electron acceptor | Cereibacter sphaeroides |
General Information | Comment | Organism |
---|---|---|
evolution | the members of the flavin adenosine dinucleotide (FAD)-dependent acyl-CoA dehydrogenase and acyl-CoA oxidase families catalyze similar reactions and share common structural features. But both enzyme families feature opposing reaction specificities in respect to dioxygen. Dehydrogenases react with electron transfer flavoproteins as terminal electron acceptors and do not show a considerable reactivity with dioxygen, whereas dioxygen serves as a bona fide substrate for oxidases | Cereibacter sphaeroides |
malfunction | convertion of (2S)-methylsuccinyl-CoA dehydrogenase (Mcd), a member of the ACAD enzyme family, into a (2S)-methylsuccinyl-CoA oxidase (Mco) through three active site mutations | Cereibacter sphaeroides |
physiological function | acyl-CoA dehydrogenases (ACADs) are flavoproteins that catalyze the flavin adenosine dinucleotide (FAD)-dependent oxidation of alpha,beta-carbon bonds in acyl-CoA thioesters. ACADs are found in all kingdoms of life and are part of various metabolic pathways, such as amino acid oxidation, choline metabolism and most prominently, the initial step in fatty acid beta-oxidation. ACADs transfer the electrons from the substrate to an electron transfer flavoprotein (ETF), which in turn funnels the electrons into a membrane bound electron transport chain and from there to the final electron acceptor. The reaction of ACADs can be divided into a reductive and an oxidative half-reaction. The reductive half-reaction is initiated by abstraction of the pro-R-alpha-proton of the acyl-CoA thioester by a conserved active site glutamate. The concomitant hydride transfer of the pro-R-beta-hydrogen to the N5 atom of the isoalloxazine ring of the FAD cofactor proceeds via an enolate-like intermediate, which forms a charge-transfer complex (CTC) with the FAD. Although the substrate is rapidly converted into the CTC, no product is formed in the absence of ETF or another suitable electron acceptor The reaction is completed with the electron transfer from the CTC to ETF during the oxidative half-reaction. The oxidative half-reaction consists of two successive inter-protein one-electron transfers between reduced ACAD and two oxidized ETFs. This results in the re-oxidation of the ACAD bound FAD and yields two ETFs in the semiquinone state (ETFsq). In contrast to ACADs, acyl-CoA oxidases (ACXs) do not require an ETF partner and directly use dioxygen as a final electron acceptor | Cereibacter sphaeroides |