Nature and properties of hexitol transport systems in Escherichia coli.

摘要: In Escherichia coli K-12 the naturally occurring hexitols D-mannitol, D-glucitol, and galactitol are taken up phosphorylated via three distinct transport systems by a mechanism called either group translocation or vectorial phosphorylation. For every system, membrane-bound enzyme II-complex of phosphoenolpyruvate-dependent phosphotransferase system has been found, each requiring phosphoenolpyruvate, I, HPr alternatively P-HPr as phosphate donor. Cells with constitutive synthesis all hexitol but low levels have very phosphorylating activities in vivo, although 40 to 90% detected cell extracts such mutants. No indications for additional systems, especially able accumulate free Klebsiella aerogenes, found. Substrate Km, Vmax several analogues determined growth rates, activities, vitro activities. Each was found take hexitols, only one serves inducer. This inducer invariably is substrate highest affinity. Since bacterial general rule, seem relatively broad specificity, contrast more restricted we propose name inducible D-mannitol coded gene mtlA D-glucitol gutA gatA system.