| Topic | Key findings (concise) | Evidence type (review/primary; organism) | Quantitative data (if any) | Primary source (authors, year) | Publication date (month/year if available) | URL | PaperQA citation id (pqac-...) |
|---|---|---|---|---|---|---|---|
| identity | PP_4191 is explicitly annotated as **SdhA, succinate dehydrogenase flavoprotein subunit** in *Pseudomonas putida* KT2440, matching UniProt Q88FA7. | Primary; *P. putida* KT2440 | Not reported | Chavarría et al., 2012 | 05/2012 | https://doi.org/10.1128/mbio.00028-12 | (pqac-00000004) |
| reaction/EC | Succinate dehydrogenase (complex II) catalyzes **succinate → fumarate + 2H+ + 2e−** and couples this to **quinone reduction (Q → QH2)**, consistent with EC 1.3.5.1. | Review; general SDH biology | Stoichiometry given in review; no strain-specific kinetic values | Bouillaud, 2023 | 02/2023 | https://doi.org/10.3390/ijms24044045 | (pqac-00000001) |
| role/pathway | SDH/complex II links the **TCA cycle** and **electron transport chain**; SdhA is the catalytic flavoprotein subunit of this respiratory enzyme. | Review + primary; general bacteria | Not reported for KT2440 | Bouillaud, 2023; McNeil et al., 2012 | 02/2023; 05/2012 | https://doi.org/10.3390/ijms24044045 ; https://doi.org/10.1074/jbc.m111.293803 | (pqac-00000001, pqac-00000002) |
| cofactors | Bacterial SdhA is a **FAD-dependent flavoprotein**; SDH contains **FAD and iron** cofactors, and SdhE is required for SdhA flavinylation in bacteria. | Review + primary; general bacteria | Loss of SdhE caused ~**90% reduction in SDH activity** in Serratia model | McNeil et al., 2012; Bouillaud, 2023 | 05/2012; 02/2023 | https://doi.org/10.1074/jbc.m111.293803 ; https://doi.org/10.3390/ijms24044045 | (pqac-00000000, pqac-00000001, pqac-00000002) |
| complex subunits/operon | In KT2440, the SDH subunits are mapped as **SdhB/PP_4190**, **SdhA/PP_4191**, **SdhD/PP_4192**, and **SdhC/PP_4193**. This supports assignment of PP_4191 to the canonical bacterial SDH complex. | Primary; *P. putida* KT2440 | Not reported | Chavarría et al., 2012 | 05/2012 | https://doi.org/10.1128/mbio.00028-12 | (pqac-00000005, pqac-00000006) |
| localization | SDH is a **membrane-spanning complex** with a soluble catalytic side containing SdhA and membrane subunits that transfer electrons to quinone; bacterial experiments localized SdhA to the membrane-associated complex. | Review + primary; general bacteria | Functional SDH reported as ~**360 kDa trimeric** complex in Serratia model | Bouillaud, 2023; McNeil et al., 2012 | 02/2023; 05/2012 | https://doi.org/10.3390/ijms24044045 ; https://doi.org/10.1074/jbc.m111.293803 | (pqac-00000000, pqac-00000001) |
| regulation/expression | In *P. putida*, **sdhA expression decreases under microaerobic cultivation**, consistent with reduced succinate oxidation when oxygen becomes limiting. | Primary; *P. putida* | **~2.2-fold reduction** of sdhA expression in wild type under microaerobic vs aerobic conditions | Mutyala et al., 2023 | 07/2023 | https://doi.org/10.1021/acsomega.3c02520 | (pqac-00000003) |
| phenotypes/essentiality | KT2440 transposon screening identified the **succinate dehydrogenase complex (5 genes)** among genes important for growth on minimal medium, supporting central metabolic importance, though not proving PP_4191 alone is universally essential. | Primary; *P. putida* KT2440 | Gene count only; no PP_4191-specific effect size in provided context | Molina-Henares et al., 2010 | 06/2010 | https://doi.org/10.1111/j.1462-2920.2010.02166.x | (pqac-00000004) |
| applications/engineering relevance | Because KT2440 can **reassimilate succinate using sdhAB**, downregulating or deleting sdhAB is proposed to improve biotechnological **succinate accumulation**; microaerobic repression of sdhA supports this strategy. | Primary; *P. putida* | gltA overexpression improved succinate production by **~50%**; succinate reached **4.73 ± 0.6 mM in 36 h**, ~**400%** above wild type at pH 7.5; sdhA expression reduced **~2.2-fold** microaerobically | Mutyala et al., 2023 | 07/2023 | https://doi.org/10.1021/acsomega.3c02520 | (pqac-00000003) |


*Table: This table summarizes evidence-supported functional annotation points for *Pseudomonas putida* KT2440 sdhA (PP_4191; UniProt Q88FA7), including identity, biochemistry, pathway role, localization, and engineering relevance. It only includes claims directly supported by the available evidence contexts.*