| Aspect | Key points | Supporting sources |
|---|---|---|
| identity/operon | • Verified target matches **E. coli K-12 manX**, annotated as the **mannose-specific PTS EIIAB component**. • Retrieved sources place **manX** with **manY/manZ** in the **manXYZ** mannose PTS locus. • Alternative naming in retrieved texts includes **EIIAB-Man**; broader PTS schematics show the mannose-family EIIAB module. | (pqac-00000001, pqac-00000003, pqac-00000005) |
| domains/subunits | • **ManX** is the **cytosolic EIIAB** phosphotransfer subunit of the mannose-family PTS. • **ManY/ManZ** correspond to the membrane **EIIC/EIID (or EIICD)** transport subunits. • This supports a split system with soluble phosphotransfer and membrane translocation components. | (pqac-00000000, pqac-00000001, pqac-00000003) |
| reaction/mechanism | • ManX functions in the **PEP-dependent phosphotransferase system (PTS)**, where phosphate flows **PEP → EI → HPr → EII components → incoming sugar**. • Retrieved texts support **phosphoryl-transfer-coupled uptake**, but do **not directly provide the EC assignment**. • **EC 2.7.1.191 is reported in the UniProt target description; not directly evidenced in retrieved texts**. | (pqac-00000001, pqac-00000004, pqac-00000006) |
| substrates | • Core assignment is **mannose-specific** transport. • Retrieved evidence also indicates **cross-specificity/promiscuity** toward **glucose, GlcNAc, GlcN, 2-deoxyglucose, fructose, and other hexoses** in some assay/database contexts. • Thus, ManX belongs to a mannose-family PTS with broader hexose/amino-sugar handling than mannose alone. | (pqac-00000000, pqac-00000002, pqac-00000003, pqac-00000004) |
| localization | • ManX is annotated as **IM, C**, consistent with a **cytosolic/peripheral phosphotransfer component associated with the inner membrane complex**. • **ManY/ManZ** are **inner-membrane** components that provide the translocation pathway. • System architecture therefore places catalysis at the cytosolic side of an inner-membrane transporter complex. | (pqac-00000000, pqac-00000003) |
| regulation/physiology | • A 2024 Cra review places **manX/manY/manZ** within broader carbon-control circuitry of the PTS. • A 2024 growth-law study engineered the **manXYZ** locus by swapping the **PptsG** promoter upstream of **manX**, deleting **mlc**, and strengthening **manA** expression. • Engineered cells grew on mannose as fast as WT on glucose; WT glucose vs WT mannose and WT mannose vs engineered mannose were both **P < 0.0001**, while WT glucose vs engineered mannose was **ns**, indicating regulation/expression—not intrinsic substrate chemistry alone—limits mannose performance. | (pqac-00000001, pqac-00000005, pqac-00000007, pqac-00000008, pqac-00000009) |
| applications/engineering | • **Transport engineering** in E. coli exploits mannose-family PTS components as alternative or enhanced sugar-uptake routes. • Rewiring **manXYZ/manX** expression can convert mannose from a relatively poor to a high-performance substrate for growth. • Recent metabolic-engineering contexts also mention **manXYZ deletion or exploitation** when redirecting carbohydrate flux or controlling uptake of amino sugars/analogs. | (pqac-00000004, pqac-00000007, pqac-00000008) |


*Table: This table summarizes the evidence-backed functional annotation of E. coli K-12 ManX (UniProt P69797), including identity, mechanism, substrates, localization, regulation, and engineering relevance. It uses only the retrieved context sources and flags where UniProt information was not directly evidenced in those texts.*