3-Isopropylmalate dehydrogenase (beta-isopropylmalate dehydrogenase, EC 1.1.1.85) of Saccharomyces cerevisiae, catalysing the third step of the leucine-specific branch of branched-chain amino acid biosynthesis: NAD+-dependent oxidative decarboxylation of (2R,3S)-3-isopropylmalate to 4-methyl-2-oxopentanoate (alpha-ketoisocaproate), which is then transaminated to leucine by Bat1/Bat2. Leu2 belongs to the isocitrate/isopropylmalate dehydrogenase family, requires Mg2+ or Mn2+, and is a soluble cytosolic enzyme. LEU2 transcription is repressed by leucine and activated by Leu3 bound to 2-isopropylmalate. leu2 mutations cause leucine auxotrophy, and LEU2 is one of the most widely used selectable markers in yeast genetics. Leu2 can also oxidatively decarboxylate the analogue beta-ethylmalate in vitro.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000287 magnesium ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro-based Mg2+ binding; IPMDH binds one Mg2+ or Mn2+ per subunit for catalysis. Reason: Cofactor binding underlying catalysis; non-core. Supporting Evidence: file:yeast/LEU2/LEU2-uniprot.txt Note=Binds 1 Mg(2+) or Mn(2+) ion per subunit. {ECO:0000250}; |
| GO:0003862 3-isopropylmalate dehydrogenase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA of the family-defining IPMDH activity; Leu2 lies within the LeuB clade and has its own experimental support. Core. Supporting Evidence: PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0003862 3-isopropylmalate dehydrogenase activity | IDA PMID:3071718 Beta-isopropylmalate dehydrogenase from yeast. | ACCEPT | Summary: Purification/characterisation of yeast beta-isopropylmalate dehydrogenase (Methods in Enzymology chapter; abstract not available). Deferring to the curator; activity is unambiguous. Core. Supporting Evidence: PMID:3071718 Beta-isopropylmalate dehydrogenase from yeast. PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0003862 3-isopropylmalate dehydrogenase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic EC/RHEA mapping (EC 1.1.1.85). Core. Supporting Evidence: PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0003862 3-isopropylmalate dehydrogenase activity | IMP PMID:6297759 Nucleotide sequence of yeast LEU2 shows 5'-noncoding region ... | ACCEPT | Summary: IMP from LEU2 cloning/sequencing (abstract does not describe the mutant data; deferring to the curator). Leucine auxotrophs blocked at the dehydrogenase step independently support the activity. Core. Supporting Evidence: PMID:6297759 The LEU2 structural gene and its regulatory sequences were isolated on a 2200 bp Xho I-Sal I fragment. PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0003862 3-isopropylmalate dehydrogenase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways BCAA superpathway assignment. Core. Supporting Evidence: PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0003862 3-isopropylmalate dehydrogenase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways leucine-biosynthesis assignment. Core. Supporting Evidence: PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping (cytoplasm); correct, though cytosol is more precise. Supporting Evidence: PMID:4355481 practically all of the isopropylmalate isomerase and the beta-isopropylmalate dehydrogenase was released into the 30,000 x g supernatant fraction, as was the cytosol marker enzyme, glucose-6-phosphate dehydrogenase |
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA (is_active_in cytosol); consistent with fractionation data. Supporting Evidence: PMID:4355481 practically all of the isopropylmalate isomerase and the beta-isopropylmalate dehydrogenase was released into the 30,000 x g supernatant fraction, as was the cytosol marker enzyme, glucose-6-phosphate dehydrogenase |
| GO:0005829 cytosol | IDA PMID:4355481 Subcellular localization of the leucine biosynthetic enzymes... | ACCEPT | Summary: Fractionation shows beta-isopropylmalate dehydrogenase is soluble/cytosolic. Supporting Evidence: PMID:4355481 practically all of the isopropylmalate isomerase and the beta-isopropylmalate dehydrogenase was released into the 30,000 x g supernatant fraction, as was the cytosol marker enzyme, glucose-6-phosphate dehydrogenase |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways cytosolic placement; consistent with fractionation. Supporting Evidence: PMID:4355481 practically all of the isopropylmalate isomerase and the beta-isopropylmalate dehydrogenase was released into the 30,000 x g supernatant fraction, as was the cytosol marker enzyme, glucose-6-phosphate dehydrogenase |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways cytosolic placement; consistent with fractionation. Supporting Evidence: PMID:4355481 practically all of the isopropylmalate isomerase and the beta-isopropylmalate dehydrogenase was released into the 30,000 x g supernatant fraction, as was the cytosol marker enzyme, glucose-6-phosphate dehydrogenase |
| GO:0006097 glyoxylate cycle | IMP PMID:23642236 A novel pathway to produce butanol and isobutanol in Sacchar... | REMOVE | Summary: The cited study (full text read) proposes a glycine -> glyoxylate -> beta-ethylmalate -> alpha-ketovalerate -> butanol route and shows that Leu2 contributes to conversion of beta-ethylmalate (formed from glyoxylate and butyryl-CoA by malate synthase) in coupled in vitro assays. This is promiscuous activity on a substrate analogue in an engineered/proposed fusel-alcohol pathway, not participation in the glyoxylate cycle (the isocitrate lyase/malate synthase bypass of the TCA cycle). Leu2 performs no step of the glyoxylate cycle. Reason: GO:0006097 glyoxylate cycle is defined by the isocitrate lyase and malate synthase reactions; the paper's evidence concerns Leu2 acting on beta-ethylmalate downstream of glyoxylate in a putative butanol pathway, which is not the glyoxylate cycle. Supporting Evidence: PMID:23642236 The second coupled reaction, catalyzed by the Leu2 activity, utilizes the produced Ξ²-ethylmalate to generate Ξ±-ketovalerate and releasing NADH as reduced equivalent. PMID:23642236 Concluding, these data indicate that the presence of LEU2 coupled with malate synthase activity guarantees the glyoxylate conversion into Ξ±-ketovalerate. |
| GO:0009082 branched-chain amino acid biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: Correct parent of leucine biosynthesis. Supporting Evidence: PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. |
| GO:0009098 L-leucine biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA; Leu2 catalyses step 3 of leucine biosynthesis. Core. Supporting Evidence: PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0009098 L-leucine biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic annotation consistent with experimental data. Core. Supporting Evidence: PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0009098 L-leucine biosynthetic process | IMP PMID:6297759 Nucleotide sequence of yeast LEU2 shows 5'-noncoding region ... | ACCEPT | Summary: IMP from LEU2 cloning study; leu2 mutants are leucine auxotrophs. Deferring to the curator on full-text details. Core. Supporting Evidence: PMID:6297759 The LEU2 structural gene and its regulatory sequences were isolated on a 2200 bp Xho I-Sal I fragment. PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. |
| GO:0009098 L-leucine biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways leucine biosynthesis. Core. Supporting Evidence: PMID:5724969 Stocks with lesions in three loci (le-2, le-3, and le-9) were primarily blocked in the third step of the pathway, catalyzed by beta-isopropylmalate dehydrogenase. file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0016616 oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro-based parent of 3-isopropylmalate dehydrogenase activity; correct but less specific. Reason: Redundant with the specific IPMDH activity term. Supporting Evidence: file:yeast/LEU2/LEU2-uniprot.txt -!- FUNCTION: Catalyzes the oxidation of 3-carboxy-2-hydroxy-4- |
| GO:0051287 NAD binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro-based NAD binding; NAD+ is the cosubstrate of IPMDH. Reason: Cosubstrate binding underlying catalysis; non-core. Supporting Evidence: file:yeast/LEU2/LEU2-uniprot.txt + CO2 + NADH; Xref=Rhea:RHEA:32271, ChEBI:CHEBI:16526, |
Loading supporting contentβ¦
Download this section (compressed HTML)Beta-isopropylmalate dehydrogenase (IMDH); catalyzes the third step in the leucine biosynthesis pathway; can additionally catalyze the conversion of beta-ethylmalate into alpha-ketovalerate
Loading supporting contentβ¦
Download this section (compressed HTML)Loading supporting contentβ¦
Download this section (compressed HTML)