4.1.2.9: phosphoketolase
This is an abbreviated version!
For detailed information about phosphoketolase, go to the full flat file.
Word Map on EC 4.1.2.9
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4.1.2.9
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pentose
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xylose
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heterofermentative
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fructose-6-phosphate
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leuconostoc
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bifidobacteria
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phosphotransacetylase
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biotechnology
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embden-meyerhof-parnas
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heterolactic
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bifid
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synthesis
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xylulokinase
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acetylphosphate
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erythrose
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acetyl-coa-derived
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bifidobacteriaceae
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industry
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pharmacology
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biofuel production
- 4.1.2.9
- pentose
- xylose
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heterofermentative
- fructose-6-phosphate
- leuconostoc
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bifidobacteria
- phosphotransacetylase
- biotechnology
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embden-meyerhof-parnas
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heterolactic
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bifid
- synthesis
- xylulokinase
- acetylphosphate
- erythrose
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acetyl-coa-derived
- bifidobacteriaceae
- industry
- pharmacology
- biofuel production
Reaction
Synonyms
CAC1343, D-xylulose 5-phosphate phosphoketolase, D-Xylulose-5-phosphate D-glyceraldehyde-3-phosphate-lyase, D-Xylulose-5-phosphate phosphoketolase, FXPK, Pentulose-5-phosphate phosphoketolase, PhK, phosphoketolase, phosphoketolase-1, phosphoketolase-2, PKT, Pu5PPK, slr0453, X5P/F6P phosphoketolase, X5PPK, Xfp, XFPK, XPK, XpkA, xylulose-5-phosphate phosphoketolase, xylulose-5-phosphate/fructose-6-phosphate phosphoketolase
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General Information on EC 4.1.2.9 - phosphoketolase
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GENERAL INFORMATION 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
evolution
phylogenetic analysis of bacterial and fungal phosphoketolases, fungal phosphoketolases are of bacterial origin
malfunction
disruption of the putative phosphoketolase gene in wild-type Synechocystis leads to a deficiency in acetate production in the dark, indicative of a contribution of the phosphoketolase pathway to heterotrophic metabolism
metabolism
physiological function
metabolism
lactic acid bacteria produce lactate, acetate, ethanol and carbon dioxide using the phosphoketolase pathway. When fructose is present, the redox balance can be maintained by the production of mannitol, which enables the formation of acetate instead of ethanol. The phosphoketolase has a lower energy yield in the form of ATP compared to that of the Embden-Meyerhof pathway (2 ATP for the Embden-Meyerhof pathway vs. only 1 for the phosphoketolase pathway) but it is used by lactic acid bacteria to ferment pentoses
metabolism
members from the order Bifidobacteriales differ from all other organisms in using a unique pathway for carbohydrate metabolism, known as the "bifid shunt", which utilizes the enzyme phosphoketolase to carry out the phosphorolysis of both fructose-6-phosphate and xylulose-5-phosphate. The existence of the bifid shunt allows bifidobacteria to produce more ATP from carbohydrates than through other conventional pathways. In contrast to bifidobacteria, the phosphoketolases found in other organisms (referred to XPK) are able to metabolize primarily xylulose-5-phosphate and show very little activity towards fructose-6-phosphate
metabolism
mutation of the gene encoding phosphoketolase almost completely abolishes flux through the pentose phosphoketolase pathway during growth on arabinose and results in decreased acetate/butyrate ratios
metabolism
the enzyme catalyzes the formation of acetyl-phosphate, which enzymatically can be converted into acetyl-CoA key precursor in central carbon metabolism
metabolism
AJD88698.1
the enzyme catalyzes the formation of acetyl-phosphate, which enzymatically can be converted into acetyl-CoA key precursor in central carbon metabolism
metabolism
KHD36088.1
the enzyme catalyzes the formation of acetyl-phosphate, which enzymatically can be converted into acetyl-CoA key precursor in central carbon metabolism
metabolism
KRU18827.1, KRU19755.1
the enzyme catalyzes the formation of acetyl-phosphate, which enzymatically can be converted into acetyl-CoA key precursor in central carbon metabolism
metabolism
the enzyme catalyzes the formation of acetyl-phosphate, which enzymatically can be converted into acetyl-CoA key precursor in central carbon metabolism
metabolism
the enzyme catalyzes the formation of acetyl-phosphate, which enzymatically can be converted into acetyl-CoA-A key precursor in central carbon metabolism
metabolism
KRU18827.1, KRU19755.1
the enzyme catalyzes the formation of acetyl-phosphate, which enzymatically can be converted into acetyl-CoA-A key precursor in central carbon metabolism
metabolism
the enzyme is indispensable for acetate production in the dark in all tested genetic backgrounds and nutrient conditions, which supports its physiological role as a phosphoketolase in the central carbon metabolism
metabolism
the enzyme is involved in pentose phosphoketolase pathway. This pathway has a primary role in arabinose metabolism of Clostridium acetobutylicum
metabolism
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the phosphoketolase pathway functions in heterofermentative bacteria where carbon flux through two sugar catabolic pathways to mixed acids (lactic acid and acetic acid) increases cellular ATP production. This pathway also serves as an alternative route to produce acetyl-CoA that bypasses the CO2 lost through pyruvate decarboxylation in the Embden-Meyerhof-Parnas pathway
metabolism
the phosphoketolase route as a mechanism of acetyl-CoA synthesis provides an advantage to microbes whose carbon assimilation proceeds via de novo formation of the C-C bond. The draft analysis of the Methylomicrobium alcaliphilum genome reveals the open reading frames (ORFs) that encode a putative D-xylulose 5-phosphate/D-fructose 6-phosphate phosphoketolase (XFP, EC 4.1.2.9/EC 4.1.2.22) and acetate kinase (AcK, EC 2.7.2.1). The co-location of the xfp- and ack-like genes in the chromosome indicates that the phosphoketolase pathway in Methylomicrobium alcaliphilum 20Z can represent a pathway for phosphosugars breakdown and an additional source of C2 compounds for acetyl-CoA synthesis
metabolism
Limosilactobacillus reuteri DSM 200160
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lactic acid bacteria produce lactate, acetate, ethanol and carbon dioxide using the phosphoketolase pathway. When fructose is present, the redox balance can be maintained by the production of mannitol, which enables the formation of acetate instead of ethanol. The phosphoketolase has a lower energy yield in the form of ATP compared to that of the Embden-Meyerhof pathway (2 ATP for the Embden-Meyerhof pathway vs. only 1 for the phosphoketolase pathway) but it is used by lactic acid bacteria to ferment pentoses
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metabolism
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the phosphoketolase pathway functions in heterofermentative bacteria where carbon flux through two sugar catabolic pathways to mixed acids (lactic acid and acetic acid) increases cellular ATP production. This pathway also serves as an alternative route to produce acetyl-CoA that bypasses the CO2 lost through pyruvate decarboxylation in the Embden-Meyerhof-Parnas pathway
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metabolism
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lactic acid bacteria produce lactate, acetate, ethanol and carbon dioxide using the phosphoketolase pathway. When fructose is present, the redox balance can be maintained by the production of mannitol, which enables the formation of acetate instead of ethanol. The phosphoketolase has a lower energy yield in the form of ATP compared to that of the Embden-Meyerhof pathway (2 ATP for the Embden-Meyerhof pathway vs. only 1 for the phosphoketolase pathway) but it is used by lactic acid bacteria to ferment pentoses
-
metabolism
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the phosphoketolase route as a mechanism of acetyl-CoA synthesis provides an advantage to microbes whose carbon assimilation proceeds via de novo formation of the C-C bond. The draft analysis of the Methylomicrobium alcaliphilum genome reveals the open reading frames (ORFs) that encode a putative D-xylulose 5-phosphate/D-fructose 6-phosphate phosphoketolase (XFP, EC 4.1.2.9/EC 4.1.2.22) and acetate kinase (AcK, EC 2.7.2.1). The co-location of the xfp- and ack-like genes in the chromosome indicates that the phosphoketolase pathway in Methylomicrobium alcaliphilum 20Z can represent a pathway for phosphosugars breakdown and an additional source of C2 compounds for acetyl-CoA synthesis
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physiological function
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a phosphoketolase disruption mutant harboring the pXylRAB gene for catabolism of xylose lacks the phosphoketolase pathway and produces predominantly lactic acid from xylose via the pentose phosphate pathway, although its fermentation rate slightly decreases. Further introduction of the transketolase gene to disrupted phosphoketolase locus leads to restoration of the fermentation rate. As a result, the strain produces 50.1 g/l of L-lactic acid from xylose with a optical purity of 99.6% and a yield of 1.58 mol per mole xylose consumed
physiological function
the phosphoketolase pathway is active and contributes up to 40% of the xylose catabolic flux in Clostridium acetobutylicum. The split ratio of the phosphoketolase pathway to the pentose phosphate pathway is markedly increased when the xylose concentration in the culture medium is increased from 10 to 20 g per liter. A phosphoketolase-overexpressing strain shows slightly increased rates of cell growth and xylose consumption during the exponential growth phase. During the subsequent solventogenic phase, the phosphoketolase-overexpressing strain exhibits a strongly reduced xylose uptake rate and solvent yields and a high level of accumulation of acetate up to 75 mM. Unlike the control strain, the phosphoketolase-overexpressing strain does not reassimilate acetate at the solventogenic phase
physiological function
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the phosphoketolase pathway is active and contributes up to 40% of the xylose catabolic flux in Clostridium acetobutylicum. The split ratio of the phosphoketolase pathway to the pentose phosphate pathway is markedly increased when the xylose concentration in the culture medium is increased from 10 to 20 g per liter. A phosphoketolase-overexpressing strain shows slightly increased rates of cell growth and xylose consumption during the exponential growth phase. During the subsequent solventogenic phase, the phosphoketolase-overexpressing strain exhibits a strongly reduced xylose uptake rate and solvent yields and a high level of accumulation of acetate up to 75 mM. Unlike the control strain, the phosphoketolase-overexpressing strain does not reassimilate acetate at the solventogenic phase
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