Metabolic Modeling Tutorial
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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
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MetaCyc Enzyme: C7-cyclitol kinase

Gene: valC Accession Number: G-10505 (MetaCyc)

Species: Streptomyces hygroscopicus jinggangensis

Summary:
The subunit structure of this enzyme has not been reported.

The product of gene valC encodes a protein that is 98% identical to VldC of Streptomyces hygroscopicus var. limoneus, and similar (32% identity, 41% similarity) to the AcbM phosphotransferase of acarbose biosynthesis in Actinoplanes. All three contain a conserved bacterial glucokinase motif and an ATP binding motif. The involvement of ValC in validamycin A biosynthesis was shown by gene inactivation studies. Recombinant, polyhistidine-tagged valC gene product was expressed in Escherichia coli and purified. Its apparent molecular mass was determined by SDS-PAGE [Minagawa07].

Gene Citations: [Yu05, Bai06]

Molecular Weight of Polypeptide: 35.966 kD (from nucleotide sequence), 40.0 kD (experimental) [Minagawa07 ]

Unification Links: Protein Model Portal:Q3T6E2 , UniProt:Q3T6E2

Relationship Links: Entrez-Nucleotide:RELATED-TO:DQ164098 , InterPro:IN-FAMILY:IPR000600 , Pfam:IN-FAMILY:PF00480

Gene-Reaction Schematic: ?

Credits:
Created 27-Feb-2008 by Fulcher CA , SRI International


Enzymatic reaction of: validone kinase (C7-cyclitol kinase)

validone + ATP <=> validone 7-phosphate + ADP + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: validamycin A biosynthesis

Summary:
This C7-cyclitol kinase catalyzes the phosphorylation of valienone and validone with very similar catalytic rates. The Kcat for validone was 7.3 s-1 and the Kcat/Km was 286 mM-1s-1. ATP was used as a phosphate donor in the pyruvate kinase/lactate dehydrogenase coupled assay system. 2-epi-5-epi-valiolone, 5-epi-valiolone, D-glucose, D-fructose, D-mannose and D-mannitol were not substrates for this enzyme [Minagawa07].

Kinetic Parameters:

Substrate
Km (μM)
Citations
validone
26.0
[Minagawa07]


Enzymatic reaction of: valienone kinase (C7-cyclitol kinase)

valienone + ATP <=> valienone 7-phosphate + ADP + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: validamycin A biosynthesis

Summary:
This C7-cyclitol kinase catalyzes the phosphorylation of valienone and validone with very similar catalytic rates. The Kcat for valienone was 3.5 s-1 and the Kcat/Km was 180 mM-1s-1. ATP was used as a phosphate donor in the pyruvate kinase/lactate dehydrogenase coupled assay system. 2-epi-5-epi-valiolone, 5-epi-valiolone, D-glucose, D-fructose, D-mannose and D-mannitol were not substrates for this enzyme [Minagawa07].

The identity of the reaction product, valienone 7-phosphate, was confirmed by ESI-MS and NMR spectroscopy. The results suggested that valienone was phosphorylated regioselectively at the C-7 hydroxy group [Minagawa07].

Kinetic Parameters:

Substrate
Km (μM)
Citations
valienone
19.0
[Minagawa07]


References

Bai06: Bai L, Li L, Xu H, Minagawa K, Yu Y, Zhang Y, Zhou X, Floss HG, Mahmud T, Deng Z (2006). "Functional analysis of the validamycin biosynthetic gene cluster and engineered production of validoxylamine A." Chem Biol 13(4);387-97. PMID: 16632251

Minagawa07: Minagawa K, Zhang Y, Ito T, Bai L, Deng Z, Mahmud T (2007). "ValC, a new type of C7-Cyclitol kinase involved in the biosynthesis of the antifungal agent validamycin A." Chembiochem 8(6);632-41. PMID: 17335096

Yu05: Yu Y, Bai L, Minagawa K, Jian X, Li L, Li J, Chen S, Cao E, Mahmud T, Floss HG, Zhou X, Deng Z (2005). "Gene cluster responsible for validamycin biosynthesis in Streptomyces hygroscopicus subsp. jinggangensis 5008." Appl Environ Microbiol 71(9);5066-76. PMID: 16151088


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 Fri Dec 19, 2014, biocyc14.