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Pathway: superpathway of glucose fermentation

Biochemical pathways in S. cerevisiae are manually curated and maintained in the YeastPathways database. This page summarizes the genes, enzymes, and metabolites involved in the pathway, along with the curated literature.

Pathway Name
superpathway of glucose fermentation
Pathway ID
GLUCFERMEN-PWY
SGD ID
SGD:S000249727
Genes
ADH1 | ADH2 | ADH3 | ADH4 | ADH5 | ALD2 | ALD4 | ALD5 | ALD6 | CDC19 | ENO1 | ENO2 | FBA1 | FBP1 | GLK1 | GPM1 | HXK1 | HXK2 | PDC1 | PDC5 | PDC6 | PFK1 | PFK2 | PGI1 | PGK1 | PYK2 | TDH1 | TDH2 | TDH3 | TPI1
Aliases
ethanol fermentation ; ethanol biosynthesis ; alcoholic fermentation
Chemical Compounds
2,3-bisphosphonato-D-glycerate(5-) | 2-phosphonato-D-glycerate(3-) | 3-phosphonato-D-glycerate(3-) | 3-phosphonato-D-glyceroyl phosphate(4-) | ADP(3-) | ATP(4-) | D-glucopyranose | D-glucopyranose 6-phosphate | D-glyceraldehyde 3-phosphate(2-) | NAD(1-) | NAD(P)(+) | NAD(P)H | NADH(2-) | NADP(3-) | NADPH(4-) | acetaldehyde | acetate | aldehyde | beta-D-fructofuranose 1,6-bisphosphate(4-) | beta-D-fructofuranose 6-phosphate(2-) | carbon dioxide | carboxylic acid anion | ethanol | glycerone phosphate(2-) | hydrogenphosphate | hydron | phosphonatoenolpyruvate | pyruvate | water

Pathway Diagram

Diagram of the pathway from YeastPathways. Click "View interactive diagram at YeastPathways" for the zoomable, clickable version.

superpathway of glucose fermentation pathway diagram

View interactive diagram at YeastPathways

Pathway Summary

Glycolysis consists of ten reactions that can be conceptually split into an energy investment and phase and an energy-producing phase. In the initial energy investment phase, 2 molecules of ATP are consumed to convert glucose into fructose-1,6-bisphosphate. In the downstream energy producing phase, fructose-1,6-bisphosphate is then broken down into two 3-carbon sugars that are each converted into a molecule of pyruvate. 2 ATP and 1 NADH are produced for each 3-carbon sugar converted to pyruvate, therefore glycolysis nets 2 ATP, 2 NADH, and 2 pyruvate molecules for each glucose fed through the pathway. In S. cerevisiae, further degradation of pyruvate can occur via respiration or fermentation. The respiration pathway involves the complete oxidation of pyruvate to CO2 via pyruvate dehydrogenase and the TCA cycle, yielding ATP and reduced cofactors (e.g. NADH) that can be oxidized in the mitochondria to produce more ATP. In the fermentation pathway, pyruvate is decarboxylated by pyruvate decarboxylase to acetaldehyde, which is then reduced to ethanol by alcohol dehydrogenase. The respiratory pathway in S. cerevisiae yields approximately 16 ATP per glucose, whereas the fermentation pathway results in a net gain of only two ATP per glucose. Despite the greater ATP-to-glucose ratio afforded by the respiration pathway, S. cerevisiae nevertheless ferments glucose in the presence of oxygen when this sugar is abundant in the growth medium. This phenomenon- the fermentation of sugar under aerobic conditions- is referred to as the Crabtree effect. In the respiratory pathway, pyruvate dehydrogenase (PDH) converts pyruvate to acetyl-CoA in the mitochondrion. However, because S. cerevisiae is unable to transport acetyl-CoA from the mitochondrion to the cytoplasm, this organism utilizes an alternative, cytosolic pathway known as the PDH bypass to generate cytosolic acetyl-CoA from pyruvate by using acetate as an intermediate. The PDH bypass involves the concerted action of pyruvate decarboxylase, which converts pyruvate to acetaldehyde; acetaldehyde dehydrogenase, which oxidizes acetaldehyde to acetate; and acetyl-CoA synthetase, which ligates acetate with coenzyme A to form acetyl-CoA. The PDH bypass is the source of the acetate that accumulates in S. cerevisiae cultures when shifted from glucose limitation to glucose excess.

Genes Involved

Genes whose products participate in this pathway, with their systematic names, EC numbers (where the gene product is an enzyme with an assigned EC number), and the gene's SGD description.

GeneSystematic NameEC NumberDescription
ADH1 YOL086C 1.1.1.1, 1.1.1.54, 1.1.1.78 Alcohol dehydrogenase
ADH2 YMR303C 1.1.1.1 Glucose-repressible alcohol dehydrogenase II
ADH3 YMR083W 1.1.1.1 Mitochondrial alcohol dehydrogenase isozyme III
ADH4 YGL256W 1.1.1.1 Alcohol dehydrogenase isoenzyme type IV
ADH5 YBR145W 1.1.1.1 Alcohol dehydrogenase isoenzyme V
ALD2 YMR170C 1.2.1.3 Cytoplasmic aldehyde dehydrogenase
ALD4 YOR374W 1.2.1.5 Mitochondrial aldehyde dehydrogenase
ALD5 YER073W 1.2.1.4 Mitochondrial aldehyde dehydrogenase
ALD6 YPL061W 1.2.1.4 Cytosolic aldehyde dehydrogenase
CDC19 YAL038W 2.7.1.40 Pyruvate kinase
ENO1 YGR254W 4.2.1.11 Enolase I, a phosphopyruvate hydratase
ENO2 YHR174W 4.2.1.11 Enolase II, a phosphopyruvate hydratase
FBA1 YKL060C 4.1.2.13 Fructose 1,6-bisphosphate aldolase
FBP1 YLR377C 3.1.3.11 Fructose-1,6-bisphosphatase
GLK1 YCL040W 2.7.1.2 Glucokinase
GPM1 YKL152C 5.4.2.11 Tetrameric phosphoglycerate mutase
HXK1 YFR053C 2.7.1.1 Hexokinase isoenzyme 1
HXK2 YGL253W 2.7.1.1 Hexokinase isoenzyme 2
PDC1 YLR044C 4.1.1.43, 4.1.1.72, 4.1.1.74 Major of three pyruvate decarboxylase isozymes
PDC5 YLR134W 4.1.1.43, 4.1.1.72, 4.1.1.74 Minor isoform of pyruvate decarboxylase
PDC6 YGR087C 4.1.1.43, 4.1.1.72, 4.1.1.74 Minor isoform of pyruvate decarboxylase
PFK1 YGR240C 2.7.1.11 Alpha subunit of heterooctameric phosphofructokinase
PFK2 YMR205C 2.7.1.11 Beta subunit of heterooctameric phosphofructokinase
PGI1 YBR196C 5.3.1.9 Glycolytic enzyme phosphoglucose isomerase
PGK1 YCR012W 2.7.2.3 3-phosphoglycerate kinase
PYK2 YOR347C 2.7.1.40 Pyruvate kinase
TDH1 YJL052W 1.2.1.12 Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), isozyme 1
TDH2 YJR009C 1.2.1.12 Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), isozyme 2
TDH3 YGR192C 1.2.1.12 Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), isozyme 3
TPI1 YDR050C 5.3.1.1 Triose phosphate isomerase, abundant glycolytic enzyme

Functional Networks

Functional Networks show how the genes in this pathway work together: a graph linking the pathway to its genes and their shared GO biological-process terms and phenotype observables, and the GO-CAM causal activity models that involve these genes.

Shared Annotations

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GO-CAMs

GO-CAM (Gene Ontology Causal Activity Model) pathway models that involve the genes in this pathway. A gene can participate in more than one model, so use the dropdown to switch between them; the model for this pathway is shown by default.

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GO Enrichment

Gene Ontology biological-process terms enriched among the genes in this pathway, computed with GO Term Finder. Terms are shown with the number of pathway genes annotated to them and the corrected p-value.

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References

List of references used specifically to curate the information on this page.

Resources

YeastPathways