A monoclonal antibody reacts with maltose-binding protein of Escherichia coli and related enteric bacteria

Maltose-binding protein (MBP) encoded by malE is essential for the energy-dependent translocation of maltose through the cytoplasmic membrane of bacteria. Its property of specific binding to maltose has been used in constructing fusion proteins for easy affinity purification. A monoclonal antibody named MAb SC1D7 was produced against Escherichia coli MBP. This MAb also bound to MBP-containing recombinant proteins in both Western blotting and immunoprecipitation analysis. As a result, this MAb can be a useful probe for tracing MBP-fusion proteins in various applications. Furthermore, intrinsic MBPs from E. coli, Shigela dysenteriae, Salmonella typhimurium, Enterobacter cloacae, and Klebsiella pneumoniae were also detected by this MAb. No reaction was observed with the total proteins from Serratia marcescens, Aeromonas hydrophila and Plesiomonas shigelloides. These observations suggest that the MAb SC1D7-defined epitope is conserved among some enteric bacteria, but not the others. The results strengthen the phylogenetic positions of these closely related bacteria previously placed by other means.