MetaCyc Enzyme: hexulose-6-phosphate synthase

Gene: rmpA Accession Number: G-3185 (MetaCyc)

Synonyms: HPS, 3-hexulose-6-phosphate synthase

Species: Mycobacterium gastri MN19

Subunit composition of hexulose-6-phosphate synthase = [RmpA]2
         hexulose-6-phosphate synthase subunit = RmpA

Hexulose-6-phosphate synthase (HPS) is one of the key enzymes of the ribulose-5-monophosphate (RuMP) pathway for formaldehyde assimilation. It is also a key enzyme of the related cyclic formaldehyde oxidation (dissimilatory) pathway which is often found in the organisms that poccess the RuMP cycle.
The gene encoding 3-hexulose-6-phosphate synthase is usually present in the same operon as the gene encoding 6-phospho-3-hexuloisomerase, the other key enzyme of the RuMP pathway.

Gene Citations: [Mitsui00]

Locations: cytosol

Molecular Weight of Polypeptide: 24 kD (experimental) [Kato90]

Molecular Weight of Multimer: 43 kD (experimental) [Kato90]

Relationship Links: Entrez-Nucleotide:PART-OF:AB034913

Gene-Reaction Schematic

Gene-Reaction Schematic

GO Terms:
Cellular Component:
GO:0005829 - cytosol [Kato90]

MultiFun Terms: metabolismcarbon utilizationcarbon compounds

Enzymatic reaction of: hexulose-6-phosphate synthase

Inferred from experiment

EC Number:

hexulose 6-phosphate ← D-ribulose 5-phosphate + formaldehyde

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the Enzyme Commission system.

The reaction is favored in the opposite direction.

In Pathways: formaldehyde assimilation II (RuMP Cycle), formaldehyde oxidation I

Cofactors or Prosthetic Groups: Mn2+ [Kato90], Mg2+ [Kato90]

Inhibitors (Competitive): EDTA [Kato90] Inhibitors (Unknown Mechanism): tiron [Kato90], o-phenanthroline [Kato90]Kinetic Parameters:
Substrate Km (μM) Citations
formaldehyde 1400.0 [Kato90]

pH(opt): 7.5 [Kato90]


Kato90: Kato N (1990). "3-Hexulose-6-phosphate synthase from Mycobacterium gastri MB19." Methods Enzymol 188;397-401. PMID: 2280712

Mitsui00: Mitsui R, Sakai Y, Yasueda H, Kato N (2000). "A novel operon encoding formaldehyde fixation: the ribulose monophosphate pathway in the gram-positive facultative methylotrophic bacterium Mycobacterium gastri MB19." J Bacteriol 182(4);944-8. PMID: 10648518

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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 19.5 on Fri Nov 27, 2015, BIOCYC13A.