Reaction: [protein]-Nπ-phospho-L-histidine + L-ascorbate[side 1] = [protein]-L-histidine + L-ascorbate 6-phosphate[side 2]
Other name(s): ulaABC (gene names); L-ascorbate PTS permease; EIISga; Enzyme IISga; Enzyme IIUla
Systematic name: protein-Nπ-phospho-L-histidine:L-ascorbate Nπ-phosphotransferase
Comments: This enzyme is a component (known as enzyme II) of a phosphoenolpyruvate (PEP)-dependent, sugar transporting phosphotransferase system (PTS). The system, which is found only in prokaryotes, simultaneously transports its substrate from the periplasm or extracellular space into the cytoplasm and phosphorylates it. The phosphate donor, which is shared among the different systems, is a phospho-carrier protein of low molecular mass that has been phosphorylated by EC 2.7.3.9 (phosphoenolpyruvate—protein phosphotransferase). Enzyme II, on the other hand, is specific for a particular substrate, although in some cases alternative substrates can be transported with lower efficiency. The reaction involves a successive transfer of the phosphate group to several amino acids within the enzyme before the final transfer to the substrate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Zhang, Z., Aboulwafa, M., Smith, M.H. and Saier, M.H., Jr. The ascorbate transporter of Escherichia coli, J. Bacteriol. 185 (2003) 2243-2250. [PMID: 12644495]
2. Hvorup, R., Chang, A.B. and Saier, M.H., Jr. Bioinformatic analyses of the bacterial L-ascorbate phosphotransferase system permease family. J. Mol. Microbiol. Biotechnol. 6 (2003) 191-205. [PMID: 15153772]
3. Luo, P., Yu, X., Wang, W., Fan, S., Li, X. and Wang, J. Crystal structure of a phosphorylation-coupled vitamin C transporter. Nat. Struct. Mol. Biol. 22 (2015) 238-241. [PMID: 25686089]