HemL is a cytoplasmic, pyridoxal-5'-phosphate-dependent glutamate-1-semialdehyde 2,1-aminomutase. It catalyzes the second reaction of the C5 glutamyl-tRNA route, rearranging the HemA product glutamate 1-semialdehyde to 5-aminolevulinate, the common precursor for the subsequent porphyrin pathway.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: The soluble HemL enzyme is predicted to function in the bacterial cytoplasm. Reason: UniProt explicitly assigns cytoplasmic localization and no targeting or membrane feature. Supporting Evidence: file:PSEPK/hemL/hemL-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: PLP is the established cofactor for HemL-family aminomutases. Reason: PLP binding is valid cofactor information, but the substrate-specific aminomutase activity is the core molecular function. Supporting Evidence: file:PSEPK/hemL/hemL-uniprot.txt Name=pyridoxal 5'-phosphate; Xref=ChEBI:CHEBI:597326; |
| GO:0033014 tetrapyrrole biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: HemL directly supplies 5-aminolevulinate for tetrapyrrole synthesis. Reason: HemL completes 5-aminolevulinate formation in the C5 route, which occurs in bacteria, archaea, and plastid-bearing eukaryotes and can feed multiple tetrapyrrole products. GO:0033014 accurately captures that direct role without relying on an obsolete route-specific term. Supporting Evidence: file:PSEPK/hemL/hemL-uniprot.txt biosynthesis; 5-aminolevulinate from L-glutamyl-tRNA(Glu): step 2/2. PMID:7883699 be used by Pseudomonas aeruginosa, Pseudomonas putida, Pseudomonas stutzeri, |
| GO:0042286 glutamate-1-semialdehyde 2,1-aminomutase activity | IEA GO_REF:0000120 | ACCEPT | Summary: This term precisely identifies the HemL reaction. Reason: The curated HAMAP rule MF_00375 (HemL_aminotrans_3) and the NCBIfam TIGR00713 hemL family place the protein in the HemL subfamily of class-III PLP-dependent aminotransferases, whose members rearrange glutamate 1-semialdehyde to ALA. Rule- and family-level evidence; the KT2440 enzyme has not been assayed. Supporting Evidence: file:PSEPK/hemL/hemL-uniprot.txt aminotransferase family. HemL subfamily. file:PSEPK/hemL/hemL-uniprot.txt DR NCBIfam; TIGR00713; hemL; 1. |
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Download this section (compressed HTML)Q: Does HemL abundance or PLP occupancy limit C5-route flux in KT2440?
Experiment: Compare growth and porphyrin intermediates after hemL depletion with and without exogenous ALA rescue.
Hypothesis: HemL supplies essentially all endogenous ALA in KT2440.
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