| Feature | Summary for *Pseudomonas putida* KT2440 icd (PP_4011; UniProt Q88FS2) | Evidence |
|---|---|---|
| Gene/protein identity | **icd / PP_4011** encodes **isocitrate dehydrogenase [NADP]**, a bacterial type I IDH/ICD in central carbon metabolism; the literature explicitly maps **icd/PP_4011** to isocitrate dehydrogenase in *P. putida* KT2440. | (pqac-00000002) |
| Enzyme name and EC | **Isocitrate dehydrogenase (NADP-dependent), EC 1.1.1.42**. This enzyme belongs to the TCA-cycle oxidative decarboxylation step that converts isocitrate to 2-oxoglutarate while reducing NADP+. | (pqac-00000001, pqac-00000002) |
| Reaction catalyzed | Catalyzes the oxidative decarboxylation of **isocitrate + NADP+ → 2-oxoglutarate + CO2 + NADPH**; in KT2440 it is discussed as a major **NADPH-generating** dehydrogenase connected to the TCA cycle and redox balance. | (pqac-00000001, pqac-00000003) |
| Cofactor specificity | Strongly **NADP-preferring** rather than NAD-specific. A broader biochemical survey of KT2440 dehydrogenases states that isocitrate dehydrogenase shows **>80% specificity for NADP+ over NAD+**. | (pqac-00000001) |
| Quantitative cofactor data | In cell-free extracts from exponentially growing KT2440 on glucose, Icd activity was **11.5 ± 1.9% with NAD+** vs **88.5 ± 6.6% with NADP+** under saturating conditions, and **11.1 ± 0.9% with NAD+** vs **88.9 ± 2.3% with NADP+** under non-saturating quasi-*in vivo* conditions. | (pqac-00000002, pqac-00000004) |
| Cellular localization | Functional context and metabolic-network placement indicate a **cytoplasmic soluble enzyme** acting in the intracellular TCA-cycle/redox network; the cited studies analyze Icd activity in **cell-free extracts** and place it within central cytosolic carbon metabolism rather than in membrane/periplasmic oxidation routes. | (pqac-00000002, pqac-00000003) |
| Pathway context | Icd sits at the branchpoint between the **TCA cycle** and the **glyoxylate shunt** and contributes reducing power to KT2440’s redox economy. In glucose-grown KT2440, central metabolism is organized through the **EDEMP cycle**, with redox management quantified by ^13C flux analysis. | (pqac-00000001, pqac-00000003) |
| Regulation: phosphorylation / AceK mention | A KT2440 multi-omics study reported a **decrease in phosphorylation of the ICD-associated protein PP_4011** during growth on glucose:benzoate versus glucose alone, suggesting post-translational tuning of flux around the ICD/glyoxylate-shunt node. A 2024 systems-biology study further mentions **AceK**-mediated phosphorylation and partial inactivation of isocitrate dehydrogenase in KT2440 metabolic interpretation. | (pqac-00000003) |
| Quantitative systems data linked to function | In mixed-substrate growth, the ICD/glyoxylate node was associated with a **>10-fold increase in acetyl-CoA** and a **37% increase in NAD(P)H yield** in glucose-only cells relative to glucose:benzoate conditions, supporting the view that ICD helps coordinate redox output with carbon-source-dependent flux partitioning. | (pqac-00000003) |


*Table: This table summarizes the core functional-annotation points for *Pseudomonas putida* KT2440 icd/PP_4011, including identity, reaction, cofactor preference, localization, regulatory context, and quantitative measurements. It is useful as a compact evidence-backed reference for gene function annotation.*