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discounted EARLY registration ends Dec 31, 2014
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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
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for maintenance.
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discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
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MetaCyc Enzyme: α-ketoglutarate semialdehyde dehydrogenase

Gene: HVO_B0039 Accession Number: G-12647 (MetaCyc)

Species: Haloferax volcanii

Subunit composition of α-ketoglutarate semialdehyde dehydrogenase = [HVO_B0039]4
         α-ketoglutarate semialdehyde dehydrogenase subunit = HVO_B0039

Summary:
The native multimer apparent molecular mass of 233 kDa was determined by gel filtration chromatography [Johnsen09].

This dehydrogenase was shown to catalyze the terminal reaction in the oxidative α-D-xylopyranose (D-xylose) degradation pathway in the halophilic archaeon Haloferax volcanii. It showed 44% amino acid sequence identity to the characterized ortholog from the Sulfolobus solfataricus D-arabinose degradation pathway (see pathway D-arabinose degradation III), 30% identity to isozyme 1 from the bacterium Azospirillum brasilense L-arabinose degradation pathway (see pathway L-arabinose degradation III), and 45% identity to the putative ortholog in the Caulobacter crescentus CB15 xylose gene cluster. Among other halophilic archaea, orthologs in Haloarcula marismortui and Halorubrum lacusprofundi showed 63% and 74% identity, respectively [Johnsen09].

Many α-ketoglutarate semialdehyde dehydrogenases that have been characterized are approximately 200 kDa homotetramers although they differ in cofactor specificity (NADP+ vs NAD+).

Native enzyme was purified from extracts of α-D-xylopyranose grown cells. Recombinant, His-tagged enzyme was expressed in Escherichia coli, but it was catalytically inactive due to misfolding after expression in a nonhalophilic organism. The enzyme was reactivated by denaturation in urea followed by refolding in the presence of salts and substrates, and was purified and characterized [Johnsen09].
The native subunit apparent molecular mass was determined by SDS-PAGE to be 75 kDa. The discrepancy with the calculated molecular mass of 50.6 kDa is common in halophilic proteins [Johnsen09].
The genome of this organism is composed of a main chromosome of 2.848 Mb, three smaller chromosomes (pHV4, pHV3 and pHV1) and a plasmid pHV2 [Hartman10]. This gene is located on pHV3.

Map Position: [43,203 -> 44,651]

Molecular Weight of Polypeptide: 50.657 kD (from nucleotide sequence), 75.0 kD (experimental) [Johnsen09 ]

Molecular Weight of Multimer: 233.0 kD (experimental) [Johnsen09]

Unification Links: Entrez-gene:8919187 , Protein Model Portal:D4GP41 , UniProt:D4GP41

Relationship Links: InterPro:IN-FAMILY:IPR015590 , InterPro:IN-FAMILY:IPR016160 , InterPro:IN-FAMILY:IPR016161 , InterPro:IN-FAMILY:IPR016162 , InterPro:IN-FAMILY:IPR016163 , Pfam:IN-FAMILY:PF00171 , Prosite:IN-FAMILY:PS00070

Gene-Reaction Schematic: ?

Credits:
Created 18-Mar-2011 by Fulcher CA , SRI International


Enzymatic reaction of: α-ketoglutarate semialdehyde dehydrogenase

Synonyms: α-ketoglutaric semialdehyde dehydrogenase, 2,5-dioxopentanoate dehydrogenase

EC Number: 1.2.1.26

2,5-dioxopentanoate + NADP+ + H2O <=> 2-oxoglutarate + NADPH + 2 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 direction shown.

Alternative Substrates for 2,5-dioxopentanoate: glutaraldehyde [Johnsen09 ] , succinate semialdehyde [Johnsen09 ]

In Pathways: superpathway of pentose and pentitol degradation , xylose degradation III

Summary:
This enzyme converts 2,5-dioxopentanoate (α-ketoglutarate semialdehyde) to 2-oxoglutarate (α-ketoglutarate). The native enzyme showed a high preference for NADP+ over NAD+ as cofactor [Johnsen09].

Kinetic Parameters:

Substrate
Km (μM)
Citations
NADP+
30.0
[Johnsen09]


References

Hartman10: Hartman AL, Norais C, Badger JH, Delmas S, Haldenby S, Madupu R, Robinson J, Khouri H, Ren Q, Lowe TM, Maupin-Furlow J, Pohlschroder M, Daniels C, Pfeiffer F, Allers T, Eisen JA (2010). "The complete genome sequence of Haloferax volcanii DS2, a model archaeon." PLoS One 5(3);e9605. PMID: 20333302

Johnsen09: Johnsen U, Dambeck M, Zaiss H, Fuhrer T, Soppa J, Sauer U, Schonheit P (2009). "D-xylose degradation pathway in the halophilic archaeon Haloferax volcanii." J Biol Chem 284(40);27290-303. PMID: 19584053


Report Errors or Provide Feedback
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 18.5 on Sun Dec 21, 2014, BIOCYC14B.