| Aspect | Summary for *Pseudomonas putida* KT2440 amgK (PP_0405; UniProt Q88QT3) | Evidence |
|---|---|---|
| Enzyme name / EC | AmgK is an N-acetylmuramate/N-acetylglucosamine kinase, also described as an anomeric sugar kinase; UniProt assigns EC 2.7.1.221. In *P. putida* KT2440 literature, amgK corresponds to PP_0405 and lies adjacent to murU/pp0406. | (pqac-00000032, pqac-00000002) |
| Reaction and products | AmgK catalyzes C1/anomeric phosphorylation of MurNAc to MurNAc-α-1-phosphate (MurNAc-1P), which MurU then converts to UDP-MurNAc in the salvage pathway. Experimental systems also use AmgK to generate GlcNAc-1P from GlcNAc. | (pqac-00000000, pqac-00000002, pqac-00000027) |
| Substrate specificity | Primary physiological substrate is MurNAc; later methods papers and pathway descriptions also identify AmgK as MurNAc/GlcNAc kinase and show formation of α-1-phosphorylated products from NAM probes and GlcNAc in vitro. Available retrieved texts support permissive recognition of modified NAM analogs, while detailed kinetic constants specific to *P. putida* AmgK were not retrieved. | (pqac-00000002, pqac-00000027, pqac-00000006) |
| Pathway context | AmgK functions in the anabolic peptidoglycan recycling route: AnhMurNAc is processed by AnmK to MurNAc-6P, MupP dephosphorylates to MurNAc, AmgK rephosphorylates at C1 to MurNAc-1P, and MurU forms UDP-MurNAc. This bypasses the MurA/MurB-dependent de novo route targeted by fosfomycin. | (pqac-00000032, pqac-00000001, pqac-00000036) |
| Cellular localization inference | The pathway acts after muropeptide import and cytoplasmic processing; therefore AmgK is inferred to function in the cytoplasm rather than the periplasm or membrane. No direct localization experiment for PP_0405 was retrieved. | (pqac-00000002, pqac-00000032) |
| Genetic / phenotypic evidence in *P. putida* | Prior work cited in the *mBio* 2017 study states that MurNAc accumulates in a ΔamgK mutant of *P. putida*, consistent with blockage of MurNAc→MurNAc-1P conversion. Deletion of amgK increases fosfomycin susceptibility in *P. putida*; ortholog complementation across *Pseudomonas* restores wild-type susceptibility in related studies summarized by reviews. | (pqac-00000000, pqac-00000014, pqac-00000032) |
| Broader relevance | The AmgK–MurU pathway is broadly conserved among many Gram-negative bacteria and contributes to intrinsic fosfomycin resistance by maintaining UDP-MurNAc despite MurA inhibition. Reviews highlight distribution in pathogens such as *Pseudomonas*, *Neisseria*, *Burkholderia*, *Brucella*, and *Legionella*. | (pqac-00000035, pqac-00000013, pqac-00000003) |
| Real-world applications | AmgK/MurU are exploited for metabolic incorporation of MurNAc-derived probes into peptidoglycan. In 2024 live-cell labeling studies, endogenous or heterologous AmgK/MurU enabled rapid, no-wash imaging of PG in *P. putida*, *P. aeruginosa*, and engineered strains, with proposed use in antibiotic screening and possibly pathogen detection in patient samples. | (pqac-00000028, pqac-00000029, pqac-00000010, pqac-00000011) |
| Quantitative data available | Blocking the salvage pathway yields a reported 4- to 8-fold increase in fosfomycin susceptibility in *Pseudomonas* spp. Reviews of related recycling enzymes report Km values ~180–1,200 μM and kcat ~5–6 s⁻¹ for AnmK/AmgK/MurK/MurQ ranges, though specific *P. putida* AmgK values were not retrieved. HTz-NAM/aTCO-SiR labeling on PG showed t1/2 ≈ 1.0 ± 0.1 s in EQKU and 1.1 ± 0.3 s in BSKU; growth rescue under fosfomycin occurred with HTz-NAM as low as 0.15 mM, with probe ranges of 0.06–6 mM tested. | (pqac-00000001, pqac-00000013, pqac-00000029, pqac-00000027) |
| Key references | Borisova M, Gisin J, Mayer C. “The *N*-Acetylmuramic Acid 6-Phosphate Phosphatase MupP Completes the *Pseudomonas* Peptidoglycan Recycling Pathway Leading to Intrinsic Fosfomycin Resistance.” *mBio* (May 2017), https://doi.org/10.1128/mbio.00092-17. Hillman AS et al. “Minimalist Tetrazine N-Acetyl Muramic Acid Probes for Rapid and Efficient Labeling of Commensal and Pathogenic Peptidoglycans in Living Bacterial Culture and During Macrophage Invasion.” *JACS* (Mar 1, 2024), https://doi.org/10.1021/jacs.3c13644. Zheng D et al. “Differences in Fosfomycin Resistance Mechanisms between *Pseudomonas aeruginosa* and *Enterobacterales*.” *Antimicrob Agents Chemother* (Feb 2022), https://doi.org/10.1128/aac.01446-21. Sonnabend MS et al. “Identification of Drug Resistance Determinants in a Clinical Isolate of *Pseudomonas aeruginosa* by High-Density Transposon Mutagenesis.” *Antimicrob Agents Chemother* (Feb 21, 2020), https://doi.org/10.1128/AAC.01771-19. | (pqac-00000032, pqac-00000028, pqac-00000036, pqac-00000031) |


*Table: This table summarizes the verified identity, biochemical role, pathway context, phenotypes, applications, and key citations for amgK/PP_0405 in *Pseudomonas putida* KT2440. It is useful as a concise evidence map for functional annotation grounded in organism-specific and pathway-level literature.*