HemA is the glutamyl-tRNA reductase that initiates the C5 glutamyl-tRNA route to 5-aminolevulinate. It uses NADPH to reduce glutamyl-tRNA(Glu), releasing tRNA(Glu) and forming glutamate 1-semialdehyde for conversion by HemL. This commits a translation-linked glutamyl-tRNA substrate to tetrapyrrole and heme precursor synthesis.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0008883 glutamyl-tRNA reductase (NADP+) activity | IEA GO_REF:0000120 | ACCEPT | Summary: This is the defining catalytic activity of HemA. Reason: UniProt assigns EC 1.2.1.70 and describes NADPH-dependent reduction of glutamyl-tRNA(Glu) to glutamate 1-semialdehyde. The GO identifier and canonical activity label are correct. Supporting Evidence: file:PSEPK/hemA/hemA-uniprot.txt Catalyzes the NADPH-dependent reduction of glutamyl-tRNA(Glu) file:PSEPK/hemA/hemA-deep-research-openscientist.md The gene **hemA** (ordered locus **PP_0732**; UniProt **Q88PW6**) of *Pseudomonas putida* KT2440 encodes **glutamyl-tRNA reductase (GluTR; EC 1.2.1.70)** |
| GO:0033014 tetrapyrrole biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: HemA directly supplies the first committed intermediate of tetrapyrrole synthesis. Reason: The C5 route occurs in multiple tetrapyrrole-producing lineages and its early intermediates can feed several tetrapyrrole end products. GO:0033014 is therefore an accurate direct process annotation without implying a narrower, now-obsolete route term. Supporting Evidence: file:PSEPK/hemA/hemA-uniprot.txt biosynthesis; 5-aminolevulinate from L-glutamyl-tRNA(Glu): step 1/2. PMID:7883699 be used by Pseudomonas aeruginosa, Pseudomonas putida, Pseudomonas stutzeri, |
| GO:0050661 NADP binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: NADPH binding supports catalysis but is not the substrate-level core function. Reason: HemA contains an NADPH-binding domain and uses NADPH in the reductase reaction. The binding term is valid ancillary molecular-function information, while GO:0008883 captures the core activity. Supporting Evidence: file:PSEPK/hemA/hemA-uniprot.txt second domain is the NADPH-binding domain |
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Download this section (compressed HTML)Q: How is KT2440 HemA flux regulated relative to glutamyl-tRNA demand for protein synthesis under iron or oxygen limitation?
Experiment: Measure ALA and downstream porphyrin intermediates after conditional hemA depletion, with rescue by exogenous ALA.
Hypothesis: HemA is required for C5-route ALA production in KT2440.
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