| Aspect | Summary | Evidence/Citation |
|---|---|---|
| Verified identity / annotation | **groEL / groL**, locus **PP_1361**, encodes the **60 kDa chaperonin GroEL (Cpn60/Hsp60 family)** in *Pseudomonas putida* KT2440; in KT2440 transcriptomics tables it is explicitly annotated as **"chaperonin 60 kDa"** and co-listed with **groES (PP_1360)** under stress-response chaperones, matching UniProt Q88N55. | Direct KT2440 annotation and co-listing with groES under stress-response category (pqac-00000000, pqac-00000017) |
| Primary molecular function | GroEL is the **bacterial Group I chaperonin** that assists folding of non-native proteins in an **ATP-dependent GroEL/GroES cycle**. GroEL is a **double-ring tetradecamer**; apical domains bind non-native substrates, equatorial domains bind/hydrolyze ATP, and ATP-driven GroES capping creates a protected folding chamber. The system can also promote **forced unfolding/stretching** of misfolded intermediates before productive encapsulation. | Mechanistic and structural synthesis from 2023–2024 structural studies (pqac-00000005, pqac-00000007, pqac-00000009) |
| Subcellular localization | Functional localization is **cytosolic**: GroEL forms a soluble intracellular chaperonin complex that binds client proteins in the cytosol and encapsulates them inside the GroEL/GroES chamber before release back to the cytosol. In situ work visualized GroEL–GroES directly inside bacterial cells. | In situ intracellular visualization and chamber-based folding cycle (pqac-00000005, pqac-00000008) |
| Operon / obligate partner | **groES (PP_1360)** is the cognate co-chaperonin partner immediately associated with **groEL (PP_1361)** in KT2440 datasets; both genes are induced together in multiple stress conditions, consistent with the canonical **groESL** module. | Co-induction of PP_1360 groES and PP_1361 groEL in KT2440 stress datasets (pqac-00000016, pqac-00000017) |
| Regulation | In *P. putida*, groEL/groES belong to the **RpoH/σ32 heat-shock regulon**. Heat shock increases **σ32 (RpoH)** and hsp-gene expression, with groEL induction persisting longer than several other hsps. GroEL/GroES also participate in **negative-feedback control** by helping bind/inactivate σ32 under non-stress conditions. At prolonged **45°C** treatment, **AlgU** contributes importantly to rpoH control. | RpoH linkage, sustained groEL induction, and AlgU involvement in prolonged heat stress (pqac-00000001, pqac-00000003) |
| KT2440 stress response: aromatic stress | **15 min aromatic challenge** in KT2440 induces groES/groEL as part of the RpoH heat-shock response. Reported fold changes: **groES** = **1.00** (toluene), **1.50** (o-xylene), **1.45** (3MB); **groEL** = **1.10** (toluene), **1.83** (o-xylene), **1.24** (3MB). Induction strength followed toxicity order **o-xylene > toluene > 3MB** in this dataset. | Quantitative KT2440 protein fold changes after aromatic exposure (pqac-00000016) |
| KT2440 stress response: elevated pressure / oxygen | Under elevated pressure, KT2440 upregulated **groES** **+1.61** and **groEL** **+1.78**; under combined elevated pressure + elevated oxygen, **groES** **+1.77** and **groEL** **+2.19**. **rpoH** also increased (**+1.49** and **+1.57**, respectively), supporting heat-shock-like regulation of groESL. | KT2440 microarray data under industrially relevant pressure/oxygen conditions (pqac-00000017, pqac-00000000) |
| KT2440 stress response: heat shock time course | In *P. putida* KT strains, hsp genes including **groEL** increase within **10 min** after temperature upshift and correlate with rising **σ32**. Unlike some other hsp transcripts, **groEL mRNA remained high after 30 min**, indicating a relatively sustained response. | Heat-shock kinetics in *P. putida* (pqac-00000001) |
| KT2440 stress response: phenol | Phenol stress in KT2440 induces a broader chaperone/heat-shock program; GroEL is described as among the **RpoH-dependent proteins upregulated** after phenol exposure, though the excerpted evidence does **not** provide a groEL-specific fold change. | Phenol-triggered chaperone response with GroEL noted qualitatively (pqac-00000014) |
| 2023–2024 mechanistic update: asymmetric ATP-bound state | Cryo-EM showed a strongly **asymmetric ATP-bound GroEL ring** in which **4 subunits** remain in a substrate-engaged state while **3 subunits** adopt a GroES-accepting conformation, explaining how GroEL can recruit GroES without losing substrate prematurely. | Structural basis of substrate progression through the cycle (pqac-00000004, pqac-00000009) |
| 2024 in situ quantification | In cells, **~55–70%** of GroEL complexes are **asymmetric EL–ES1** (single-GroES-capped), with the remainder symmetric **EL–ES2**. At **37°C**, EL–ES1:EL–ES2 is about **60:40**; after heat stress, EL–ES1 rises to about **70%**. | In situ cryo-ET figure/table quantification (pqac-00000005, pqac-00000006, pqac-00000012) |
| 2024 abundance / stoichiometry in cells | The **GroEL:ribosome ratio** in tomograms was about **1:23** at 37°C and about **1:10** after heat stress, indicating roughly **3-fold induction** of GroEL relative to ribosomes. Heat stress also caused about **3-fold increases** in GroEL and GroES abundance. | In situ cellular quantification under normal vs heat-stress conditions (pqac-00000006, pqac-00000012) |
| Client scope / pathway role | GroEL–GroES is estimated to assist folding of about **~10% of newly synthesized proteins** in bacteria. The folding chamber generally accommodates proteins up to **~60–70 kDa**; most canonical clients are **20–40 kDa**, with a marked drop above **~50 kDa**. | Client fraction and chamber-size/client-size constraints (pqac-00000005, pqac-00000007) |


*Table: This table condenses the verified identity, core function, regulation, localization, KT2440-specific stress responses, and 2023–2024 mechanistic insights for groEL (Q88N55/PP_1361). It is useful as a compact evidence map for functional annotation and biological interpretation.*