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UniProt functional annotation for E0SRA9 | ||
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| UniProt code: E0SRA9. |
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| Organism: | |
Ignisphaera aggregans (strain DSM 17230 / JCM 13409 / AQ1.S1). |
| Taxonomy: | |
Archaea; Crenarchaeota; Thermoprotei; Desulfurococcales; Desulfurococcaceae; Ignisphaera. |
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| Function: | |
Involved in the biosynthesis of branched-chain amino acids (BCAA). Catalyzes an alkyl-migration followed by a ketol-acid reduction of (S)-2-acetolactate (S2AL) to yield (R)-2,3-dihydroxy-isovalerate. In the isomerase reaction, S2AL is rearranged via a Mg-dependent methyl migration to produce 3-hydroxy-3-methyl-2-ketobutyrate (HMKB). In the reductase reaction, this 2-ketoacid undergoes a metal-dependent reduction by NADPH or NADH to yield (R)-2,3-dihydroxy-isovalerate. {ECO:0000269|PubMed:25172159, ECO:0000269|PubMed:26644020}. |
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| Catalytic activity: | |
Reaction=(2R)-2,3-dihydroxy-3-methylbutanoate + NAD(+) = (2S)-2- acetolactate + H(+) + NADH; Xref=Rhea:RHEA:30627, ChEBI:CHEBI:15378, ChEBI:CHEBI:49072, ChEBI:CHEBI:57540, ChEBI:CHEBI:57945, ChEBI:CHEBI:58476; EC=1.1.1.383; Evidence={ECO:0000269|PubMed:25172159, ECO:0000269|PubMed:26644020}; |
| Catalytic activity: | |
Reaction=(2R)-2,3-dihydroxy-3-methylbutanoate + NADP(+) = (2S)-2- acetolactate + H(+) + NADPH; Xref=Rhea:RHEA:22068, ChEBI:CHEBI:15378, ChEBI:CHEBI:49072, ChEBI:CHEBI:57783, ChEBI:CHEBI:58349, ChEBI:CHEBI:58476; EC=1.1.1.383; Evidence={ECO:0000269|PubMed:25172159, ECO:0000269|PubMed:26644020}; |
| Cofactor: | |
Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Evidence={ECO:0000255|HAMAP-Rule:MF_00435, ECO:0000269|PubMed:25849365}; Note=Binds 2 magnesium ions per subunit. {ECO:0000255|HAMAP- Rule:MF_00435}; |
| Biophysicochemical properties: | |
Kinetic parameters: KM=3.1 mM for S2AL (at pH 7 and 85 degrees Celsius) {ECO:0000269|PubMed:26644020}; Note=Kcat is 3.3 sec(-1) for reductoisomerase activity with NADPH (at pH 7 and 85 degrees Celsius with S2AL as substrate) (PubMed:26644020). Kcat is 0.03 sec(-1) for reductoisomerase activity with NADPH (at pH 7 with S2AL as substrate) (PubMed:25172159). Kcat is 0.02 sec(-1) for reductoisomerase activity with NADH (at pH 7 with S2AL as substrate) (PubMed:25172159). {ECO:0000269|PubMed:25172159, ECO:0000269|PubMed:26644020}; |
| Pathway: | |
Amino-acid biosynthesis; L-isoleucine biosynthesis; L- isoleucine from 2-oxobutanoate: step 2/4. {ECO:0000255|HAMAP- Rule:MF_00435}. |
| Pathway: | |
Amino-acid biosynthesis; L-valine biosynthesis; L-valine from pyruvate: step 2/4. {ECO:0000255|HAMAP-Rule:MF_00435}. |
| Subunit: | |
Homodimer. {ECO:0000269|PubMed:25849365}. |
| Similarity: | |
Belongs to the ketol-acid reductoisomerase family. {ECO:0000255|HAMAP-Rule:MF_00435}. |
Annotations taken from UniProtKB at the EBI.