| Claim / functional element | Evidence type | Key quantitative data | Stress condition / context | Source and URL |
|---|---|---|---|---|
| **Identity:** PP_5108 in *P. putida* KT2440 is **rpoH**, annotated as **RNA polymerase sigma-32 factor (RpoH)** | Omics annotation + organism-specific literature | Table entry explicitly maps **PP_5108 = rpoH = RNA polymerase sigma-32 factor**; functional studies in *P. putida* state **rpoH encodes σ32** | KT2440 transcriptome under elevated pressure; KT2442 heat-shock genetics | Follonier et al. 2013 *Microbial Cell Factories* https://doi.org/10.1186/1475-2859-12-30; Ito et al. 2014 *MicrobiologyOpen* https://doi.org/10.1002/mbo3.217 (pqac-00000002, pqac-00000003) |
| **Induction kinetics:** RpoH/σ32 is rapidly induced after heat shift and correlates with hsp induction | Experiment | σ32 induction is described as transient, **peaking at ~5–15 min** after heat shock; in *P. putida*, **hsp gene expression increased within ~10 min** and correlated with σ32 level | Heat-shock response in *P. putida* KT2442 | Ito et al. 2014 *MicrobiologyOpen* https://doi.org/10.1002/mbo3.217 (pqac-00000000, pqac-00000001) |
| **Regulon size / promoter logic:** RpoH directs RNAP to heat-shock promoters; canonical σ32 promoter motif reported | Experiment + comparative regulatory analysis | E. coli σ32 regulon cited as **~50 transcriptional units / ~90 genes**; reported σ32 promoter consensus **CTTGAA N13-17 CCCCATNT**; candidate *P. putida* σ32-regulated genes include **cbpA, hfq, secA** | Heat-shock transcriptional regulation; inference used in *P. putida* promoter searches | Ito et al. 2014 *MicrobiologyOpen* https://doi.org/10.1002/mbo3.217 (pqac-00000001, pqac-00000013) |
| **Mechanistic regulation:** RpoH activity and abundance are controlled by chaperones and proteolysis | Review + experiment | **DnaK/DnaJ/GrpE** and **GroEL/GroES** bind/inactivate σ32; **FtsH** degrades σ32; *P. putida* **dnaJ** mutant is temperature sensitive and accumulates more protein aggregates, while **clpB** mutant is heat sensitive and defective in aggregate solubilization | Heat-shock quality-control circuit in cytoplasm | Ito et al. 2014 *MicrobiologyOpen* https://doi.org/10.1002/mbo3.217; Potvin et al. 2008 *FEMS Microbiology Reviews* https://doi.org/10.1111/j.1574-6976.2007.00092.x (pqac-00000003, pqac-00000008, pqac-00000011, pqac-00000012) |
| **Protein family / domain context:** RpoH is an alternative **sigma-70 family** sigma factor for heat-shock transcription | Review | RpoH shows **61% identity** to *E. coli* σ32; σ70-family architecture includes conserved **domain 2** (core RNAP binding, DNA melting, -10 recognition) and **domain 4** (HTH, -35 recognition) | General bacterial transcription; relevant to Pseudomonas RpoH annotation | Potvin et al. 2008 *FEMS Microbiology Reviews* https://doi.org/10.1111/j.1574-6976.2007.00092.x (pqac-00000004, pqac-00000011) |
| **Pressure-associated induction in KT2440:** rpoH and canonical heat-shock genes are upregulated | Omics (microarray; supported by qRT-PCR for most tested genes) | Under elevated pressure: **rpoH +1.49** (adj. P = **3.6E-03**); with pressure + O2: **+1.57** (adj. P = **8.7E-03**). Associated genes: **htpG +1.65 / +1.92**, **groES +1.61 / +1.77**, **groEL +1.78 / +2.19**, **grpE +1.33** | KT2440 under elevated pressure and elevated pressure + dissolved oxygen; bioprocess-relevant stress | Follonier et al. 2013 *Microbial Cell Factories* https://doi.org/10.1186/1475-2859-12-30 (pqac-00000007, pqac-00000009, pqac-00000010) |
| **Solvent response link:** aromatic solvent stress recruits the RpoH heat-shock program | Omics + experiment | Toluene/o-xylene exposure induced proteins assigned to the **RpoH regulon**, including **GroES, GroEL, GrpE, Lon, DnaK, IbpA**; activation of the TOL meta operon was reported to require the contribution of **σ32 and/or σ38** host factors | KT2440 exposed to toluene/aromatic solvents; proteotoxic stress tradeoff with metabolism | Domínguez-Cuevas et al. 2006 *Journal of Biological Chemistry* https://doi.org/10.1074/jbc.m509848200 (pqac-00000006) |


*Table: This table compiles organism-specific evidence supporting the functional annotation of *Pseudomonas putida* KT2440/KT2442 rpoH (PP_5108) as the sigma-32 heat-shock sigma factor. It highlights identity, regulatory mechanism, kinetics, regulon features, and stress-responsive expression data most useful for gene-function annotation.*