| Source | Year/date | URL / DOI | Evidence type | Main findings | Scope / notes |
|---|---|---|---|---|---|
| Leal-Morales et al., *Environmental Microbiology* | Dec 2022 | https://doi.org/10.1111/1462-2920.15857 | Genetic regulation mapping, promoter architecture, operon analysis | In *P. putida* KT2440, the flagellar cluster contains **59 genes**, organized into **11 operons** with **22 primary/internal promoters**; the system follows a **three-tier cascade** in which FleQ is Class I, FleQ+σ54 control Class II genes including **fliA**, and **FliA (σ28)** activates Class III genes needed for filament synthesis, one stator, and chemotaxis completion (pqac-00000006). Promoter analysis identified **21 putative flagellar promoters** overall, including **FliA-dependent motifs** upstream of **fliK2, fliC, cheV, fliS, flgM**; σ54-type motifs were found upstream of several earlier flagellar operons (pqac-00000005). The paper also describes FliA as central to feed-forward/feedback control: FliA activates late genes and promotes **flgM** expression, while hook completion enables FlgM export and FliA release (pqac-00000013, pqac-00000015). | **KT2440-specific primary study**; strongest source for operon counts, promoter classes, and regulatory hierarchy. |
| Xiao et al., *MicrobiologyOpen* | Sep 2017 | https://doi.org/10.1002/mbo3.402 | Genetics, promoter-lacZ assays, 5′-RACE, qRT-PCR, c-di-GMP biochemistry | Demonstrated that **FliA partly controls bifA** expression in *P. putida* KT2440: **fliA deletion lowered bifA transcription about twofold** and caused a **nonmotile phenotype** that was complemented by plasmid-borne fliA (pqac-00000002, pqac-00000000). **5′-RACE identified two bifA TSSs** at **103 nt** and **40 nt** upstream of the start codon, with upstream **σ70** and **σ28** promoter elements; mutation of the σ28 promoter reduced activity, and FliA overexpression in an *E. coli* reporter increased activity about **fivefold** (pqac-00000001). Reported intracellular c-di-GMP values were **23.33 pmol/mg protein** in WT vs **20.13 pmol/mg** in the **fliA mutant**; FliA overexpression promoted swimming in a **BifA-dependent** manner (pqac-00000001, pqac-00000014). | **KT2440-specific primary study**; strongest source for direct quantitative phenotypes, dual-promoter architecture at **bifA**, and c-di-GMP linkage. |
| Blanco-Romero et al., *Scientific Reports* | Sep 2018 | https://doi.org/10.1038/s41598-018-31371-z | ChIP-seq, regulon mapping (FleQ) | Defined upstream hierarchy around FliA by showing that FleQ is the master regulator of pseudomonad flagellar transcription and identified **103 putative FleQ binding sites** in *P. putida* KT2440. FleQ works with **σ54/RpoN** to activate multiple early flagellar operons, including loci that feed into the layer containing **fliA** (pqac-00000004). | **KT2440-specific primary study**, but focuses on **FleQ**, not direct FliA targets; useful for upstream regulatory context. |
| Oladosu et al., *Journal of Bacteriology* | Mar 2024 | https://doi.org/10.1128/jb.00365-23 | Expert review | Summarizes authoritative current understanding in pseudomonads: **FliA is constitutively expressed but post-translationally sequestered by FlgM**; after hook-basal body completion, **FlgM export frees FliA**, enabling late/class IV transcription such as **fliC, fleL, cheAB, motAB, cheW, cheVR, flgMN, cheYZ**. The review also highlights integration of the FliA/FlgM module with broader signaling and **c-di-GMP**-linked lifestyle regulation (pqac-00000010). | **Cross-species Pseudomonas review** centered on *P. aeruginosa*; used for conserved mechanistic interpretation, not KT2440-specific claims. |
| Lo et al., *PLoS ONE* | May 2016 | https://doi.org/10.1371/journal.pone.0155397 | Transcriptomics, reporter assays, phenotype analysis | Provides cross-species evidence that FliA regulates more than canonical flagellar genes: in *P. aeruginosa*, FliA affected expression of phosphodiesterase genes such as **PA4367/bifA**, linking FliA to **c-di-GMP metabolism**, swarming, and pigment production. The study also notes that excess FliA can trigger feedback through **flgM**, supporting careful dosage control of σ28 activity (pqac-00000011, pqac-00000012). | **Cross-species primary study**; not KT2440-specific, but supports broader interpretation of FliA as a motility–c-di-GMP network node. |


*Table: This table compiles the key KT2440-specific and comparative Pseudomonas evidence for FliA (sigma-28), including regulatory hierarchy, promoter architecture, quantitative measurements, and broader expert interpretation. It is useful for separating direct evidence in *P. putida* KT2440 from conserved mechanisms inferred from related pseudomonads.*