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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: ?

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 19.0 on Mon Aug 3, 2015, BIOCYC13A.