Reprogramming of sugar transport pathways in Escherichia coli using a permeabilized SecY protein‐translocation channel

In the initial step of sugar metabolism, sugar‐specific transporters play a decisive role in the passage of sugars through plasma membranes into cytoplasm. The SecY complex (SecYEG) in bacteria forms a membrane channel responsible for protein translocation. The present work shows that permeabilized SecY channels can be used as nonspecific sugar transporters in Escherichia coli. SecY with the plug domain deleted allowed the passage of glucose, fructose, mannose, xylose, and arabinose, and, with additional pore‐ring mutations, facilitated lactose transport, indicating that sugar passage via permeabilized SecY was independent of sugar stereospecificity. The engineered E. coli showed rapid growth on a wide spectrum of monosaccharides and benefited from the elimination of transport saturation, improvement in sugar tolerance, reduction in competitive inhibition, and prevention of carbon catabolite repression, which are usually encountered with native sugar uptake systems. The SecY channel is widespread in prokaryotes, so other bacteria may also be engineered to utilize this system for sugar uptake. The SecY channel thus provides a unique sugar passageway for future development of robust cell factories for biotechnological applications. A novel strategy for sugar transport without sugar‐specific transporters was developed in this study. The authors show that weakening the sealability of the SecY channel promoted its application in passage of sugars in Escherichia coli, including the PTS‐dependent hexoses, the non‐PTS‐dependent pentoses, and a disaccharide. As acting by a free diffusion mechanism, the most distinguishing feature of this transport is independent of sugar stereospecificity.