ThrB (PP_0121) is a Pseudomonas-type homoserine kinase that uses ATP to phosphorylate L-homoserine, producing O-phospho-L-homoserine for threonine synthase. It belongs to the type II homoserine-kinase family with an aminoglycoside-phosphotransferase-like fold. Native ThrB has been coexpressed with ThrC and heterologous ThrA in engineered KT2440 to increase threonine production.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004413 homoserine kinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Homoserine kinase is supported by a curated substrate-specific family and native cloning. Reason: HAMAP MF_00301, TIGR00938 and the Pseudomonas-type ThrB family establish the inference; the generic APH fold does not imply antibiotic phosphorylation. PMID:40236303 corroborates native construct identity and pathway engineering, not individual kinetic measurements. Supporting Evidence: file:PSEPK/thrB/thrB-uniprot.txt Reaction=L-homoserine + ATP = O-phospho-L-homoserine + ADP + H(+) file:PSEPK/thrB/thrB-uniprot.txt HAMAP; MF_00301; Homoser_kinase_2; 1. PMID:40236303 the remaining genes of the metabolic pathway – thrB and thrC – were overexpressed as well. file:PSEPK/PP_4473/PP_4473-bioinformatics/primer-identity/RESULTS.md The thrB_ecoRI_F primer matches MSVFTPVT at the N terminus of ThrB/PP_0121/Q88RK8, and thrB_not_R matches its terminal LHLPFAL. |
| GO:0009088 L-threonine biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: ThrB phosphorylates homoserine for the terminal threonine-forming reaction. Reason: The curated reaction and native ThrB/ThrC coexpression support this pathway role. P. aeruginosa ThrB/ThrH redundancy does not establish KT2440 dispensability or a native bypass. Supporting Evidence: file:PSEPK/thrB/thrB-uniprot.txt Reaction=L-homoserine + ATP = O-phospho-L-homoserine + ADP + H(+) file:PSEPK/thrB/thrB-uniprot.txt HAMAP; MF_00301; Homoser_kinase_2; 1. PMID:40236303 the remaining genes of the metabolic pathway – thrB and thrC – were overexpressed as well. |
| GO:0019202 amino acid kinase activity | IEA GO_REF:0000118 | MODIFY | Summary: Refine amino-acid kinase activity to homoserine kinase. Reason: The specific homoserine substrate is supported by HAMAP and family signatures and is already represented by GO:0004413. Proposed replacements: homoserine kinase activity Supporting Evidence: file:PSEPK/thrB/thrB-uniprot.txt Reaction=L-homoserine + ATP = O-phospho-L-homoserine + ADP + H(+) file:PSEPK/thrB/thrB-uniprot.txt HAMAP; MF_00301; Homoser_kinase_2; 1. |
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