| Type: | Domain | Name: | Phosphotransferase system, mannose-type IIA component |
| Description: | The phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) [, ] is a major carbohydrate transport system in bacteria. The PTS catalyses the phosphorylation of incoming sugar substrates and coupled with translocation across the cell membrane, makes the PTS a link between the uptake and metabolism of sugars.The general mechanism of the PTS is the following: a phosphoryl group from phosphoenolpyruvate (PEP) is transferred via a signal transduction pathway, to enzyme I (EI) which in turn transfers it to a phosphoryl carrier, the histidine protein (HPr). Phospho-HPr then transfers the phosphoryl group to a sugar-specific permease, a membrane-bound complex known as enzyme 2 (EII), which transports the sugar to the cell. EII consists of at least three structurally distinct domains IIA, IIB and IIC []. These can either be fused together in a single polypeptide chain or exist as two or three interactive chains, formerly called enzymes II (EII) and III (EIII). The first domain (IIA or EIIA) carries the first permease-specific phosphorylation site, a histidine which is phosphorylated by phospho-HPr. The second domain (IIB or EIIB) is phosphorylated by phospho-IIA on a cysteinyl or histidyl residue, depending on the sugar transported. Finally, the phosphoryl group is transferred from the IIB domain to the sugar substrate concomitantly with the sugar uptake processed by the IIC domain. This third domain (IIC or EIIC) forms the translocation channel and the specific substrate-binding site. An additional transmembrane domain IID, homologous to IIC, can be found in some PTSs, e.g. for mannose [, , , ]. According to structural and sequence analyses, the PTS EIIA domain can be divided in different groups. The mannose class of EIIA consists of a single five-stranded mixed beta sheet, flanked by helices on both sides []. The phosphorylation site (His) is located at the end of the third beta strand, in a shallow crevice lined with hydrophobic residues.This entry represents the mannose-type EIIA domain. This type of domain can also be found in the multidomain protein dihydroxyacetone kinase DhaM from some bacteria [, ]. | Short Name: | PTS_EIIA_man-typ |
