Biosynthetic threonine deaminase/dehydratase (EC 4.3.1.19) of Schizosaccharomyces pombe (SPBC1677.03c, PomBase tda1), the ortholog of S. cerevisiae Ilv1. This PLP-dependent enzyme deaminates L-threonine to 2-oxobutanoate and ammonia, the first committed step of isoleucine biosynthesis. S. pombe threonine deaminase is stimulated by pyridoxal phosphate, feedback-inhibited by isoleucine and reactivated by valine. The protein has a predicted mitochondrial transit peptide and is placed in the mitochondrial matrix by orthology, although the ORFeome screen recorded a cytoplasmic signal.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004794 threonine deaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA (PTN002459384) for threonine deaminase, seeded by experimentally characterised family members including E. coli IlvA (P04968), two S. cerevisiae dehydratases (SGD:S000000888, SGD:S000000569) and S. pombe tda1 itself (its own IDA, which is expected, not circular). Correct. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt Reaction=L-threonine = 2-oxobutanoate + NH4(+); Xref=Rhea:RHEA:22108, PMID:4698209 Biosynthetic threonine deaminase (TD) from Schizosaccharomyces pombe has been partially purified from crude extracts |
| GO:0004794 threonine deaminase activity | IDA PMID:4698209 Biosynthesis of branched-chain amino acids in Schizosaccharo... | ACCEPT | Summary: Direct assay of threonine deaminase activity in partially purified S. pombe extracts (PLP-stimulated, isoleucine-inhibited). Accept, deferring to the curator for the attribution of the extract activity to SPBC1677.03c. Supporting Evidence: PMID:4698209 Biosynthetic threonine deaminase (TD) from Schizosaccharomyces pombe has been partially purified from crude extracts PMID:4698209 TD showed marked stimulation by pyridoxal phosphate |
| GO:0004794 threonine deaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA (ARBA, InterPro IPR005787 biosynthetic threonine dehydratase, RHEA:22108, EC 4.3.1.19). Correct. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt Reaction=L-threonine = 2-oxobutanoate + NH4(+); Xref=Rhea:RHEA:22108, |
| GO:0004794 threonine deaminase activity | ISS GO_REF:0000024 | ACCEPT | Summary: UniProt ISS from S. cerevisiae Ilv1 (P00927). Correct; also supported by S. pombe extract enzymology. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt Reaction=L-threonine = 2-oxobutanoate + NH4(+); Xref=Rhea:RHEA:22108, PMID:4698209 Biosynthetic threonine deaminase (TD) from Schizosaccharomyces pombe has been partially purified from crude extracts |
| GO:0005737 cytoplasm | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: Cytoplasmic YFP signal in the ORFeome screen. Conflicts with the predicted mitochondrial transit peptide and with PomBase's own IC mitochondrial matrix annotation; a C-terminal tag on an overexpressed protein may mislocalise. Retained as non-core. Reason: High-throughput localisation that disagrees with the expected mitochondrial-matrix location. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins file:SCHPO/tda1/tda1-uniprot.txt /note="Mitochondrion" |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: UniProt subcellular-location mapping (SL-0086 Cytoplasm). The UniProt cytoplasm statement is itself taken from the ORFeome screen (PubMed:16823372), so this row repeats the HDA evidence. It conflicts with the predicted mitochondrial transit peptide and the mitochondrial location of S. cerevisiae Ilv1; retained as non-core pending direct localisation. Reason: Derived from a high-throughput tagged-protein screen; the biosynthetic enzyme is expected in mitochondria. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins file:SCHPO/tda1/tda1-uniprot.txt /note="Mitochondrion" |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping (SL-0173 Mitochondrion), by similarity to S. cerevisiae Ilv1 (P00927) and supported by a predicted N-terminal transit peptide. Accept. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion {ECO:0000250|UniProtKB:P00927}. file:SCHPO/tda1/tda1-uniprot.txt /note="Mitochondrion" |
| GO:0005739 mitochondrion | ISS GO_REF:0000024 | ACCEPT | Summary: UniProt ISS from S. cerevisiae Ilv1 (mitochondrial). Accept; consistent with the transit peptide. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion {ECO:0000250|UniProtKB:P00927}. |
| GO:0005759 mitochondrial matrix | IC GO_REF:0000111 | ACCEPT | Summary: PomBase IC (from GO:0004794) placing the activity in the mitochondrial matrix, as in the PomBase GO-CAM gomodel:6690711d00002706. Consistent with the predicted transit peptide and the matrix location of the downstream isoleucine/valine enzymes in fungi. Accept. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion {ECO:0000250|UniProtKB:P00927}. file:SCHPO/tda1/tda1-uniprot.txt /note="Mitochondrion" |
| GO:0006520 amino acid metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO (IPR000634, Ser/Thr dehydratase PLP-binding site) to the generic 'amino acid metabolic process'. True but uninformative; the specific process is L-isoleucine biosynthesis (same correction as S. cerevisiae ILV1). Proposed replacements: L-isoleucine biosynthetic process Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt PATHWAY: Amino-acid biosynthesis; L-isoleucine biosynthesis; 2- |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro2GO (IPR000634) to PLP binding. The S. pombe enzyme is stimulated by pyridoxal phosphate and UniProt lists PLP as cofactor; correct cofactor binding, non-core. Reason: Cofactor binding underlying threonine deaminase activity. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt Name=pyridoxal 5'-phosphate; Xref=ChEBI:CHEBI:597326; PMID:4698209 TD showed marked stimulation by pyridoxal phosphate |
| GO:1901705 L-isoleucine biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA (narrower node PTN002463966, with S. cerevisiae SGD:S000000888 and Arabidopsis AT3G10050 among the sources) for L-isoleucine biosynthesis; tda1 supplies 2-oxobutanoate, the committed step of isoleucine synthesis. Correct. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt PATHWAY: Amino-acid biosynthesis; L-isoleucine biosynthesis; 2- PMID:4698209 the inhibition caused by the natural feedback inhibitor, l-isoleucine |
| GO:1901705 L-isoleucine biosynthetic process | IDA PMID:4698209 Biosynthesis of branched-chain amino acids in Schizosaccharo... | ACCEPT | Summary: McDonald & Kaplan (1973) partially purified biosynthetic threonine deaminase from S. pombe and showed feedback inhibition by isoleucine and reversal by valine, the hallmark regulation of the isoleucine-pathway entry enzyme. Abstract-only cache; the gene-to-activity assignment is the PomBase curator's. Accept. Supporting Evidence: PMID:4698209 Biosynthetic threonine deaminase (TD) from Schizosaccharomyces pombe has been partially purified from crude extracts PMID:4698209 the inhibition caused by the natural feedback inhibitor, l-isoleucine PMID:4698209 l-Valine was found to reverse isoleucine inhibition |
| GO:1901705 L-isoleucine biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: ARBA/InterPro (IPR005787) mapping to L-isoleucine biosynthesis. Correct. Supporting Evidence: file:SCHPO/tda1/tda1-uniprot.txt PATHWAY: Amino-acid biosynthesis; L-isoleucine biosynthesis; 2- |
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Download this section (compressed HTML)Q: Is endogenous S. pombe tda1 mitochondrial, as predicted from its transit peptide, or partly cytosolic as recorded in the ORFeome screen?
Q: Is tda1 deletion an isoleucine auxotroph, confirming it as the sole biosynthetic threonine deaminase?
Experiment: Tag tda1 at the endogenous locus and co-localise with a mitochondrial marker; test isoleucine requirement of tda1-deleted cells.
Type: cell biology and genetics
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