MetaCyc Enzyme: NADPH-dependent succinate semialdehyde reductase

Gene: Msed_1424 Accession Number: G-10488 (MetaCyc)

Species: Metallosphaera sedula

Subunit composition of NADPH-dependent succinate semialdehyde reductase = [Msed_1424]2
         succinate semialdehyde reductase monomer = Msed_1424

The activity of this enzyme was first demonstrated in cell extract of Metallosphaera sedula by HPLC [Berg07]. The enzyme was partially purified from an extract of autotrophically grown cells and analyzed by trypsin digestion followed by peptide fingerprint mass spectrometry. The resulting data was compared with the genome, and identified the Msed_1424 gene [Kockelkorn09]. The gene was cloned, expressed in Escherichia coli and purified. The native molecular mass determined by gel filtration was 74 7 kDa, suggesting a homodimeric subunit composition. Metal analysis using plasma emission spectroscopy revealed the presence of 1.9 mol of zinc per mol of enzyme monomer.

The enzyme is very specific for its substrate, and did not use any of the other aldehydes that were tested [Kockelkorn09].

Molecular Weight of Polypeptide: 37.879 kD (from nucleotide sequence), 40.0 kD (experimental) [Kockelkorn09 ]

Molecular Weight of Multimer: 74.0 kD (experimental) [Kockelkorn09]

Unification Links: Entrez-gene:5104795 , Protein Model Portal:A4YGN0 , String:399549.Msed_1424 , UniProt:A4YGN0

Relationship Links: InterPro:IN-FAMILY:IPR002085 , InterPro:IN-FAMILY:IPR002328 , InterPro:IN-FAMILY:IPR011032 , InterPro:IN-FAMILY:IPR013149 , InterPro:IN-FAMILY:IPR013154 , InterPro:IN-FAMILY:IPR016040 , Panther:IN-FAMILY:PTHR11695 , Pfam:IN-FAMILY:PF00107 , Pfam:IN-FAMILY:PF08240 , Prosite:IN-FAMILY:PS00059

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Created 11-Feb-2008 by Caspi R , SRI International
Revised 12-Nov-2009 by Caspi R , SRI International

Enzymatic reaction of: succinate semialdehyde reductase

EC Number:

4-hydroxybutanoate + NADP+ <=> succinate semialdehyde + NADPH + H+

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.

In Pathways: 3-hydroxypropanoate/4-hydroxybutanate cycle

Enzymatic activity of cell extracts was 2500 nmol/min/mg protein at 55 ° C [Berg07]. The purified enzyme catalyzed the reaction at a rate of 700 μmol/min/mg/ protein at 65 °C [Kockelkorn09].

Activators (Allosteric): Zn2+ [Berg07]

Kinetic Parameters:

Km (μM)
succinate semialdehyde

pH(opt): 7.5 [Kockelkorn09]


Berg07: Berg IA, Kockelkorn D, Buckel W, Fuchs G (2007). "A 3-hydroxypropionate/4-hydroxybutyrate autotrophic carbon dioxide assimilation pathway in Archaea." Science 318(5857);1782-6. PMID: 18079405

Kockelkorn09: Kockelkorn D, Fuchs G (2009). "Malonic semialdehyde reductase, succinic semialdehyde reductase, and succinyl-coenzyme A reductase from Metallosphaera sedula: enzymes of the autotrophic 3-hydroxypropionate/4-hydroxybutyrate cycle in Sulfolobales." J Bacteriol 191(20);6352-62. PMID: 19684143

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Tue Oct 13, 2015, biocyc13.