Reaction: [protein]-Nπ-phospho-L-histidine + lactose[side 1] = [protein]-L-histidine + lactose 6'-phosphate[side 2]
Other name(s): lacEF (gene names); lactose PTS permease; EIILac; Enzyme IILac
Systematic name: protein-Nπ-phospho-L-histidine:lactose 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. Hengstenberg, W. Solubilization of the membrane bound lactose specific component of the staphylococcal PEP dependant phosphotransferase system. FEBS Lett. 8 (1970) 277-280. [PMID: 11947593]
2. Vadeboncoeur, C. and Proulx, M. Lactose transport in Streptococcus mutans: isolation and characterization of factor IIIlac, a specific protein component of the phosphoenolpyruvate-lactose phosphotransferase system. Infect. Immun. 46 (1984) 213-219. [PMID: 6480107]
3. Breidt, F., Jr., Hengstenberg, W., Finkeldei, U. and Stewart, G.C. Identification of the genes for the lactose-specific components of the phosphotransferase system in the lac operon of Staphylococcus aureus, J. Biol. Chem. 262 (1987) 16444-16449. [PMID: 2824493]
4. De Vos, W.M., Boerrigter, I., Van Rooijen, R.J., Reiche, B., Hengstenberg, W. Characterization of the lactose-specific enzymes of the phosphotransferase system in Lactococcus lactis, J. Biol. Chem. 265 (1990) 22554-22560. [PMID: 2125052]
5. Peters, D., Frank, R. and Hengstenberg, W. Lactose-specific enzyme II of the phosphoenolpyruvate-dependent phosphotransferase system of Staphylococcus aureus. Purification of the histidine-tagged transmembrane component IICBLac and its hydrophilic IIB domain by metal-affinity chromatography, and functional characterization. Eur. J. Biochem. 228 (1995) 798-804. [PMID: 7737179]