Carbohydrate transporters of the bacterial phosphoenolpyruvate: Sugar phosphotransferase system (PTS)
Siebold C., Flükiger K., Beutler R., Erni B.
The glucose transporter of Escherichia coli couples translocation with phosphorylation of glucose. The IICBGlc subunit spans the membrane eight times. Split, circularly permuted and cyclized forms of IICBGlc are described. The split variant was 30 times more active when the two proteins were encoded by a dicistronic mRNA than by two genes. The stability and activity of circularly permuted forms was improved when they were expressed as fusion proteins with alkaline phosphatase. Cyclized IICBGlc and IIAGlc were produced in vivo by RecA intein-mediated trans-splicing. Purified, cyclized IIAGlc and IICBGlc had 100% and 30% of wild-type glucose phosphotransferase activity, respectively. Cyclized IIAGlc displayed increased stability against temperature and GuHCl-induced unfolding. © 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.