| Evidence type | Claim (reaction/pathway/localization/regulation) | Key quantitative data | Organism/strain context | Source and URL |
|---|---|---|---|---|
| Biochemical + genetic | **PP_0774/pta encodes active phosphotransacetylase (Pta)** in *P. putida* KT2440; locus organization shown as **PP0773–PP0774(pta)–PP0775**. Pta catalyzes **acetyl-CoA + Pi ⇄ acetyl-phosphate + CoA**, with native activity detected in oxic glucose-grown cells and lost in a **pta::mini-Tn5** mutant; activity increases at transition to stationary phase, supporting a role in acetyl-CoA/acetyl-phosphate metabolism rather than a misassigned gene. No localization experiment was reported; function is consistent with a **cytosolic metabolic enzyme**. | Pta activity increased **2.2-fold** from log to stationary phase; **no significant activity** in **pta::mini-Tn5** mutant; *E. coli* comparator peaked at **12.5 ± 0.9 U mg protein⁻¹**. In oxic glucose minimal medium, **Δpta (E. coli)** comparator showed **2.3-fold lower specific growth rate** and **1.6-fold lower final biomass** than parent. (pqac-00000017) | *Pseudomonas putida* KT2440; mini-Tn5 mutant derivative; glucose-grown cells in M9 minimal medium. | Nikel & de Lorenzo 2013, *Metabolic Engineering*. https://doi.org/10.1016/j.ymben.2012.09.006 (pqac-00000013, pqac-00000017) |
| Biochemical + engineering | Native **Pta-generated acetyl-phosphate** in *P. putida* can feed heterologous **AckA** to produce **acetate + ATP** by substrate-level phosphorylation under anoxic conditions, functionally confirming the **Pta → acetyl-P** step in KT2440. This places Pta in the **AckA-Pta acetate node** linking pyruvate dehydrogenase-derived acetyl-CoA to acetyl-phosphate. | Upon **ackA** expression from *E. coli*, acetate kinase activity reached **17.8 ± 1.3 U mg protein⁻¹**; acetate secretion reached **12.9 ± 0.6 mM** vs **<1 mM** in vector control; in **pta::mini-Tn5** background, acetate secretion reverted to control-like levels. ATP/ADP ratio after 24 h anoxia was **6.2 ± 0.8**, a **1.3-fold** increase over control. AEC under anoxia fell to **0.28 ± 0.04** in control but remained **~0.62–0.69** with heterologous AckA. (pqac-00000017, pqac-00000018) | *P. putida* KT2440 carrying **Ptrc::ackA** from *E. coli* MG1655; compared with **pta::mini-Tn5** derivative under anoxic incubation. | Nikel & de Lorenzo 2013, *Metabolic Engineering*. https://doi.org/10.1016/j.ymben.2012.09.006 (pqac-00000013, pqac-00000017, pqac-00000018) |
| Engineering | In an engineered **phosphoketolase (Xfpk) shunt**, **Pta converts acetyl-phosphate to acetyl-CoA** in *P. putida*, bypassing pyruvate decarboxylation/carboxylation-associated carbon loss and improving carbon conservation into biomass and acetyl-CoA-derived products. | Xfpk candidates generated **1.26**, **1.19**, and **36.25 mM AcP/OD600** (empty-vector control **0.80 mM**); best enzyme was ~**30-fold** higher than weaker candidates. On glycerol, Xfpk increased growth rate **0.12 → 0.18 h⁻¹** (**+44.3%**) and max OD600 **4.4 → 6.6** (**+50%**). Product yields increased: flaviolin reporter **0.002 → 0.003** (**+38.5%**) and mevalonate **0.011 → 0.015 mol/mol** (**+25.9%**). On xylose, growth rate **0.02 → 0.05 h⁻¹** (**+167%**), final OD600 **5.73 → 7.4** (**+30.2%**), flaviolin **+49.4%**, mevalonate **0.022 → 0.042 mol/mol** (**+48.7%**). (pqac-00000000, pqac-00000001, pqac-00000014) | *P. putida* KT2440-derived strains (**ΔglpR**, **Δgcd-xylABE**) expressing heterologous **xfpk**. | Bruinsma et al. 2023, *Microbial Cell Factories*. https://doi.org/10.1186/s12934-022-02015-9 (pqac-00000000, pqac-00000001, pqac-00000014) |
| Pathway/physiology + application | Succinate-from-acetate work places **pta** with **ackA** and **acs** as entry routes from acetate to acetyl-CoA/TCA-glyoxylate metabolism in *P. putida*. This supports functional annotation of Pta in **acetate assimilation/acetyl-CoA supply**, even though this study did not directly manipulate **pta**. | **gltA** overexpression gave **~50%** improvement in succinate production; at pH 7.5, succinate reached **4.73 ± 0.6 mM in 36 h**, about **~400%** of wild type; yield was **9.5% of maximum theoretical** on acetate minimal medium. Figure 1 explicitly depicts **ackA/pta/acs** feeding acetyl-CoA from acetate. (pqac-00000002, pqac-00000010) | *P. putida* KT2440 and **gltA-overexpressing** derivative under microaerobic growth on acetate as sole carbon source. | Mutyala et al. 2023, *ACS Omega*. https://doi.org/10.1021/acsomega.3c02520 (pqac-00000002, pqac-00000010) |
| Engineering/application | For acetate-based **mcl-PHA** production, *P. putida* KT2440 was engineered by strengthening acetate assimilation via **acs overexpression** and constructing an **ackA-pta** pathway, indicating practical exploitation of the Pta node to channel acetate/acetyl-phosphate toward acetyl-CoA and product formation. | Engineered *P. putida* produced **0.674 g/L mcl-PHA from acetate**; later consortium optimization reported **1.32 g/L** maximum mcl-PHA from mixed glucose/xylose after further pathway engineering. The study explicitly states that in 2019 they strengthened acetate assimilation by overexpressing **acs** and constructing the **ackA-pta** pathway. (pqac-00000004, pqac-00000015) | *P. putida* KT2440 in monoculture and in a designed *P. putida–E. coli* consortium for lignocellulose conversion. | Qin et al. 2022, *Frontiers in Bioengineering and Biotechnology*. https://doi.org/10.3389/fbioe.2022.1023325 (pqac-00000004, pqac-00000015) |
| Review/regulation | In **Pseudomonas spp.**, **ackA-pta** expression is linked to anaerobic/fermentative regulation by **Anr** (Fnr homolog) and **IHF/LhfA**; acetate consumption is additionally controlled by **CrbS/R** through **Acs**, while **CidR** regulates acetate production via pyruvate:menaquinone oxidoreductase. This frames likely regulatory context for KT2440 Pta, but is not a KT2440-specific direct experiment. | No direct KT2440 enzyme kinetics given; review emphasizes that acetate metabolism can impair growth via intracellular acidification/respiratory inhibition and that **Ac-CoA/acetyl-phosphate** can alter **non-enzymatic protein acetylation**. (pqac-00000008) | Review of bacteria including *Pseudomonas* spp.; regulatory context relevant to *P. putida* but not a direct KT2440 perturbation study. | Hosmer et al. 2023, *Emerging Topics in Life Sciences*. https://doi.org/10.1042/ETLS20220092 (pqac-00000008) |


*Table: This table compiles organism-specific and closely relevant pathway evidence supporting functional annotation of *Pseudomonas putida* KT2440 pta (UniProt Q88PS4; PP_0774). It emphasizes direct biochemical/genetic support from Nikel & de Lorenzo and recent engineering studies that place Pta in acetyl-phosphate/acetyl-CoA metabolism.*