FOL3 (YMR113W) encodes dihydrofolate synthetase (DHFS, EC 6.3.2.12), an ATP-dependent glutamate ligase of the folylpolyglutamate synthetase (Mur-ligase-like) family. It attaches the first L-glutamate residue to 7,8-dihydropteroate, the product of Fol1p, forming 7,8-dihydrofolate, which Dfr1p then reduces to tetrahydrofolate. fol3 mutants lack DHFS activity and require folinic acid for growth. In S. cerevisiae the two glutamate-adding activities, which are combined in one enzyme in many bacteria, are split between paralogs: Fol3p adds the first glutamate during de novo synthesis, and Met7p is the folylpolyglutamate synthetase that extends the glutamate chain of folate coenzymes. Fol3p is a cytoplasmic protein.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004326 tetrahydrofolylpolyglutamate synthase activity | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: IBA from PTN000123998, the node at which PAINT placed both dihydrofolate synthase and folylpolyglutamate synthase activities (many bacterial FolC enzymes are bifunctional). In S. cerevisiae the two activities have been split between paralogs: Fol3p is the dihydrofolate synthetase, while folylpolyglutamate synthetase activity is encoded by MET7 (the yeast experimental source on this IBA is MET7, SGD:S000005767). met7 mutants are methionine auxotrophs despite intact FOL3, so Fol3p does not supply the polyglutamylation activity. Reason: Paralog subfunctionalisation: FPGS is Met7p; Fol3p is the DHFS. Propagation Review Root cause: PROPAGATION BAD Failure modes: WRONG ORTHOLOG OR PARALOG FUNCTIONAL DIVERGENCE Sources checked: SGD:S000005767 · MET7, yeast folylpolyglutamate synthetase paralog SUPPORTS SOURCE BUT NOT TARGET UniProtKB:P08192 · E. coli FolC (bifunctional DHFS/FPGS) SUPPORTS SOURCE BUT NOT TARGET Supporting Evidence: PMID:10799479 We show that dihydrofolate synthetase catalyzing the binding of the first glutamyl side chain to dihydropteroate yielding dihydrofolate is encoded by the YMR113w gene that we propose to rename FOL3. PMID:10799479 We show also that folylpolyglutamate synthetase, which catalyzes the extension of the glutamate chains of the folate coenzymes, is encoded by the MET7 gene. |
| GO:0004326 tetrahydrofolylpolyglutamate synthase activity | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: InterPro IPR001645/IPR018109 (folylpolyglutamate synthetase family and signature) mapped to FPGS activity. The family covers both DHFS and FPGS enzymes; in yeast FPGS is Met7p and Fol3p is the first-glutamate-adding DHFS. Reason: Family-level mapping does not distinguish the paralogs; Fol3p function is DHFS. Supporting Evidence: PMID:10799479 We show that dihydrofolate synthetase catalyzing the binding of the first glutamyl side chain to dihydropteroate yielding dihydrofolate is encoded by the YMR113w gene that we propose to rename FOL3. PMID:10799479 We show also that folylpolyglutamate synthetase, which catalyzes the extension of the glutamate chains of the folate coenzymes, is encoded by the MET7 gene. |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro (Mur-ligase-like FPGS family) mapping to ATP binding; DHFS is an ATP-dependent ligase, so this is correct but is part of the DHFS activity. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + |
| GO:0005737 cytoplasm | HDA PMID:14562095 Global analysis of protein localization in budding yeast. | ACCEPT | Summary: Huh et al. GFP survey: cytoplasmic Fol3p. Supporting Evidence: PMID:14562095 We classify these proteins, representing 75% of the yeast proteome, into 22 distinct subcellular localization categories |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000123998 for cytoplasmic activity; consistent with GFP data for Fol3p. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt SL-0086 Cytoplasm mapping from the GFP survey; correct. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: IBA from PTN000123999, seeded by the mitochondrial isoforms of FPGS (human/mouse FPGS, Arabidopsis AT3G10160 and yeast MET7). Fol3p is a different paralog (DHFS), has no reported mitochondrial targeting, and was seen only in the cytoplasm. Cherest et al. also found no evidence for a separate mitochondrial FPGS isoform in yeast. Reason: Location inherited from FPGS paralogs; not supported for Fol3p. Propagation Review Root cause: PROPAGATION BAD Failure modes: WRONG ORTHOLOG OR PARALOG COMPARTMENT OR COMPLEX MISMATCH Sources checked: SGD:S000005767 · MET7 (FPGS paralog) SUPPORTS SOURCE BUT NOT TARGET UniProtKB:Q05932 · human FPGS (mitochondrial and cytosolic isoforms) SUPPORTS SOURCE BUT NOT TARGET Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: IBA for cytosolic activity from PTN000123999 (FPGS paralogs). Although the source genes are FPGS, the location is independently consistent with the cytoplasmic GFP signal of Fol3p. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA location from ALL-CHORISMATE-PWY-1 (superpathway of chorismate metabolism); Fol3p is a soluble cytoplasmic enzyme, so cytosol is appropriate. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA location from FOLSYN-PWY-1 (superpathway of tetrahydrofolate biosynthesis and salvage); Fol3p is a soluble cytoplasmic enzyme, so cytosol is appropriate. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA location from PWY-6614 (tetrahydrofolate biosynthesis); Fol3p is a soluble cytoplasmic enzyme, so cytosol is appropriate. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA location from PWY3O-20 (folate polyglutamylation); Fol3p is a soluble cytoplasmic enzyme, so cytosol is appropriate. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA location from PWY3O-45 (folate biosynthesis II); Fol3p is a soluble cytoplasmic enzyme, so cytosol is appropriate. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0006761 dihydrofolate biosynthetic process | IEA GO_REF:0000108 | ACCEPT | Summary: Inferred from the dihydrofolate synthase activity (inter-ontology link). Fol3p makes dihydrofolate from dihydropteroate, so this is the precise core process. Supporting Evidence: PMID:10799479 We show that dihydrofolate synthetase catalyzing the binding of the first glutamyl side chain to dihydropteroate yielding dihydrofolate is encoded by the YMR113w gene that we propose to rename FOL3. file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + |
| GO:0008841 dihydrofolate synthase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000123998 with FOL3 (SGD:S000004719) as an experimental source. Core activity. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + PMID:10799479 We show that dihydrofolate synthetase catalyzing the binding of the first glutamyl side chain to dihydropteroate yielding dihydrofolate is encoded by the YMR113w gene that we propose to rename FOL3. |
| GO:0008841 dihydrofolate synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: RHEA:23584 / EC 6.3.2.12 mapping; correct. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + |
| GO:0008841 dihydrofolate synthase activity | IMP PMID:11731153 Folic acid utilisation related to sulfa drug resistance in S... | ACCEPT | Summary: Bayly et al. made a mutant specifically lacking dihydrofolate synthase by disrupting FOL3 and rescued it with folinic acid or a FOL3 plasmid. This is consistent with Cherest et al., who showed that fol3 cells have no DHFS activity. Core activity. Supporting Evidence: PMID:11731153 One mutant specifically lacked dihydropteroate synthase while the second lacked dihydrofolate synthase. PMID:10799479 Mutant cells bearing a fol3 mutation require folinic acid for growth and have no dihydrofolate synthetase activity. |
| GO:0008841 dihydrofolate synthase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA assigning EC 6.3.2.12 to FOL3 in ALL-CHORISMATE-PWY-1 (superpathway of chorismate metabolism); correct. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + |
| GO:0008841 dihydrofolate synthase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA assigning EC 6.3.2.12 to FOL3 in FOLSYN-PWY-1 (superpathway of tetrahydrofolate biosynthesis and salvage); correct. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + |
| GO:0008841 dihydrofolate synthase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA assigning EC 6.3.2.12 to FOL3 in PWY-6614 (tetrahydrofolate biosynthesis); correct. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + |
| GO:0008841 dihydrofolate synthase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA assigning EC 6.3.2.12 to FOL3 in PWY3O-20 (folate polyglutamylation); correct. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + |
| GO:0008841 dihydrofolate synthase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA assigning EC 6.3.2.12 to FOL3 in PWY3O-45 (folate biosynthesis II); correct. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Reaction=7,8-dihydropteroate + L-glutamate + ATP = 7,8-dihydrofolate + |
| GO:0009396 folic acid-containing compound biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000123998; correct broad process (Fol3p makes dihydrofolate). Reason: Broad specificity. No single child term asserted here covers this activity, which acts on dihydropteroate (dihydrofolate synthase) and folates (folylpolyglutamate synthase); this term is the lowest common ancestor of those child terms and so states the range of the activity. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Glutamate-adding enzyme which catalyzes the binding of the first glutamyl side chain to dihydropteroate. |
| GO:0009396 folic acid-containing compound biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: ARBA/InterPro mapping to folic acid-containing compound biosynthesis; correct, broad. Reason: Broad specificity. No single child term asserted here covers this activity, which acts on dihydropteroate (dihydrofolate synthase) and folates (folylpolyglutamate synthase); this term is the lowest common ancestor of those child terms and so states the range of the activity. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Glutamate-adding enzyme which catalyzes the binding of the first glutamyl side chain to dihydropteroate. |
| GO:0009396 folic acid-containing compound biosynthetic process | IMP PMID:11731153 Folic acid utilisation related to sulfa drug resistance in S... | ACCEPT | Summary: The DHFS-deficient fol3 strain needs exogenous folinic acid, showing Fol3p is required for de novo folate synthesis, in which it catalyses a step. Correct, broad. Reason: Broad specificity. No single child term asserted here covers this activity, which acts on dihydropteroate (dihydrofolate synthase) and folates (folylpolyglutamate synthase); this term is the lowest common ancestor of those child terms and so states the range of the activity. Supporting Evidence: PMID:11731153 One mutant specifically lacked dihydropteroate synthase while the second lacked dihydrofolate synthase. PMID:11731153 Exogenous folinic acid restored optimal growth to both strains. |
| GO:0016881 acid-amino acid ligase activity | IEA GO_REF:0000120 | MODIFY | Summary: ARBA/InterPro (Mur ligase C-terminal domain) mapping to the generic acid-amino acid ligase term. Correct parent but uninformative given the established specific activity. Reason: Specific activity is known. Proposed replacements: dihydrofolate synthase activity Supporting Evidence: PMID:10799479 We show that dihydrofolate synthetase catalyzing the binding of the first glutamyl side chain to dihydropteroate yielding dihydrofolate is encoded by the YMR113w gene that we propose to rename FOL3. |
| GO:0035999 folate cycle | RCA GO_REF:0000123 | REMOVE | Summary: RCA from the THF superpathway. Fol3p adds glutamate to dihydropteroate during de novo synthesis; it does not move C1 units between THF species. Reason: Not involved in C1 interconversion. |
| GO:0046417 chorismate metabolic process | RCA GO_REF:0000123 | REMOVE | Summary: RCA from the superpathway of chorismate metabolism; Fol3p glutamylates dihydropteroate and has no connection to chorismate. Reason: Superpathway inflation. |
| GO:0046654 tetrahydrofolate biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: RCA from PWY-6614 (tetrahydrofolate biosynthesis); Fol3p catalyses the step before DHFR in de novo THF synthesis. Correct process. Supporting Evidence: file:yeast/FOL3/FOL3-uniprot.txt Glutamate-adding enzyme which catalyzes the binding of the first glutamyl side chain to dihydropteroate. |
| GO:0046655 folic acid metabolic process | RCA GO_REF:0000123 | MODIFY | Summary: RCA from PWY3O-20 (folate polyglutamylation). Fol3p acts on dihydropteroate to make dihydrofolate; folic acid is not its substrate or product. Reason: Precise process is dihydrofolate biosynthesis. Proposed replacements: dihydrofolate biosynthetic process |
| GO:0046656 folic acid biosynthetic process | RCA GO_REF:0000123 | MODIFY | Summary: RCA from PWY3O-45 (folate biosynthesis II). The Fol3p product is 7,8-dihydrofolate, not folic acid. Reason: Precise process is dihydrofolate biosynthesis. Proposed replacements: dihydrofolate biosynthetic process |
| GO:0046901 tetrahydrofolylpolyglutamate biosynthetic process | IEA GO_REF:0000041 | MARK AS OVER ANNOTATED | Summary: UniPathway UPA00850 (tetrahydrofolylpolyglutamate biosynthesis) mapping. Fol3p adds only the first glutamate to dihydropteroate; polyglutamate chain extension on THF is done by Met7p (FPGS). Reason: Polyglutamylation is the MET7 step; Fol3p makes the monoglutamate. Supporting Evidence: PMID:10799479 We show also that folylpolyglutamate synthetase, which catalyzes the extension of the glutamate chains of the folate coenzymes, is encoded by the MET7 gene. |
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Download this section (compressed HTML)Q: Does Fol3p retain any residual folylpolyglutamate synthetase activity toward THF in vitro, or is it strictly specific for dihydropteroate?
Q: Where does dihydropteroate produced by mitochondrial-membrane Fol1p meet cytoplasmic Fol3p?
Experiment: Assay purified Fol3p and Met7p with dihydropteroate, THF-Glu1 and THF-Glu2 substrates; test whether FOL3 overexpression suppresses met7 methionine auxotrophy.
Hypothesis: Fol3p is specific for dihydropteroate and cannot extend THF polyglutamates
Type: enzymology / genetic suppression
Dihydrofolate synthetase, involved in folic acid biosynthesis; catalyzes conversion of dihydropteroate to dihydrofolate in folate coenzyme biosynthesis; FOL3 has a paralog, RMA1, that arose from the whole genome duplication
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