|Gene:||mcr||Accession Numbers: G-15069 (MetaCyc), Caur_2614|
Species: Chloroflexus aurantiacus
Subunit composition of
malonyl CoA reductase = [Mcr]2
malonyl CoA reductase subunit = Mcr
Malonyl CoA reductase, an enzyme that catalyzes the two-step reduction of malonyl-CoA and NADPH to 3-hydroxypropanoate via 3-oxopropanoate, has been isolated from Chloroflexus aurantiacus [Hugler02].
This bifunctional enzyme is a homodimer of 300 kDa, and consists of an N-terminal short-chain alcohol dehydrogenase domain and a C-terminal aldehyde dehydrogenase domain. It is highly specific for its substrates.
The N-terminal amino acid sequence was determined, and an incomplete gene sequence was identified in the genome database [Hugler02].
Gene Citations: [Tang11a]
Molecular Weight of Polypeptide: 131.98 kD (from nucleotide sequence), 145.0 kD (experimental) [Hugler02 ]
Molecular Weight of Multimer: 300.0 kD (experimental) [Hugler02]
Enzymatic reaction of: 3-hydroxypropionate:NADP+ oxidoreductase (malonyl CoA reductase)
EC Number: 188.8.131.528
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is favored in the opposite direction.
The enzyme has a turnover number of 25 s-1 per subunit. The specific activity in autotrophically grown cells was 0.08 μmol of malonyl-CoA reduced per min per mg protein. The value is much lower in heterotrophically grown cells, indicating downregulation under heterotrophic conditions. Specific activity of the purified protein was 10 μmol per min per mg protein [Hugler02].
Enzymatic reaction of: malonate semialdehyde:NADP+ oxidoreductase (malonate semialdehyde-forming) (malonyl CoA reductase)
EC Number: 184.108.40.206
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.
This reaction is reversible.
pH(opt): 7.8 [Hugler02]
Hugler02: Hugler M, Menendez C, Schagger H, Fuchs G (2002). "Malonyl-coenzyme A reductase from Chloroflexus aurantiacus, a key enzyme of the 3-hydroxypropionate cycle for autotrophic CO(2) fixation." J Bacteriol 184(9);2404-10. PMID: 11948153
Tang11a: Tang KH, Barry K, Chertkov O, Dalin E, Han CS, Hauser LJ, Honchak BM, Karbach LE, Land ML, Lapidus A, Larimer FW, Mikhailova N, Pitluck S, Pierson BK, Blankenship RE (2011). "Complete genome sequence of the filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus." BMC Genomics 12;334. PMID: 21714912
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