Maltoporins and maltose-binding proteins of Yersinia enterocolitica

Two components of the Yersinia enterocolitica maltose transport system, maltoporin (OmpM) and an osmotically shockable periplasmic maltose-binding protein (MBP) were identified. The synthesis of OmpM (apparent Mr 43,000) and transport of maltose into cells of Y. enterocolitica were induced by maltose and maltodextrins. A mutant lacking OmpM was drastically impaired in maltose transport, independent of induction by maltose. The MBP of Y. enterocolitica (apparent Mr 40,000) was found in the osmotic shock fluid. Its synthesis was induced by maltose. Moreover, rabbit antibodies raised against the MBP of E. coli cross-reacted with the analogous protein from Y. enterocolitica. The MBP of Y. enterocolitica restored the maltose transport activities in delta malE mutant cells of E. coli.