EryC1 (EryCI) is a pyridoxal-5'-phosphate (PLP)-dependent sugar aminotransferase of the TDP-D-desosamine biosynthetic pathway in Saccharopolyspora erythraea, installing the C-3 amino group on the deoxysugar precursor that is ultimately attached to the macrolactone by the desosaminyltransferase EryCIII. It is the eponymous member of the DegT/DnrJ/EryC1 family of PLP-dependent sugar aminotransferases. NOTE: the UniProt entry P14290 carries a legacy misannotation as an "erythromycin biosynthesis sensory transduction protein" (two-component / DNA-binding / cell-membrane), which predates characterization of the deoxysugar pathway; the family assignment (DegT/DnrJ/EryC1) and the transaminase/PLP annotations are the accurate ones.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0008483 transaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Transaminase activity - the correct molecular function. EryC1 is the founding member of the DegT/DnrJ/EryC1 PLP-dependent sugar-aminotransferase family and aminates the desosamine precursor. This (correctly) contradicts the UniProt "sensory transduction protein" name. Reason: Accurate molecular function consistent with the DegT/DnrJ/EryC1 family assignment and PLP cofactor; the defining activity of EryC1. Supporting Evidence: file:SACEN/eryCI/eryCI-uniprot.txt Belongs to the DegT/DnrJ/EryC1 family. |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000120 | ACCEPT | Summary: PLP binding - the cofactor of the sugar aminotransferase reaction (UniProt retains the Pyridoxal phosphate keyword). Reason: Correct cofactor binding for a PLP-dependent aminotransferase. Supporting Evidence: file:SACEN/eryCI/eryCI-uniprot.txt Belongs to the DegT/DnrJ/EryC1 family. |
| GO:0000271 polysaccharide biosynthetic process | IEA GO_REF:0000118 | MODIFY | Summary: Incorrect biological process. EryC1 contributes to biosynthesis of the aminodeoxysugar D-desosamine (a monosaccharide moiety of erythromycin), not a polysaccharide. Reason: Wrong process class. Replace with GO:1901115 (erythromycin biosynthetic process), the cluster-level process to which desosamine biosynthesis contributes. Proposed replacements: erythromycin biosynthetic process |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | REMOVE | Summary: Incorrect localization derived from UniProt's "Cell membrane (peripheral)" annotation, itself part of the legacy sensory/two-component misannotation. DegT/DnrJ/EryC1 sugar aminotransferases are soluble cytoplasmic enzymes. Reason: Demonstrably inappropriate: this is a soluble cytoplasmic PLP aminotransferase; the membrane location is a knock-on of the erroneous "sensory transduction protein" annotation. Supporting Evidence: file:SACEN/eryCI/eryCI-uniprot.txt Belongs to the DegT/DnrJ/EryC1 family. |
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Download this section (compressed HTML)Q: The UniProt entry P14290 should be re-curated: its "sensory transduction protein / two-component / DNA-binding / cell membrane" annotation contradicts its DegT/DnrJ/EryC1 family membership and PLP-dependent sugar-aminotransferase function. Should this be reported upstream?
Experiment: In vitro reconstitution of EryC1 with the TDP-4-keto desosamine precursor and an amino donor (e.g. glutamate) to confirm PLP-dependent sugar transaminase activity and replace the IEA annotations with experimental (IDA) evidence.
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