Amplification of a novel gene, sanA, abolishes a vancomycin-sensitive defect in Escherichia coli

We have isolated an Escherichia coli gene which, when overexpressed, is able to complement the permeability defects of a vancomycin-susceptible mutant. This gene, designated sanA, is located at min 47 of the E. coli chromosome and codes for a 20-kDa protein with a highly hydrophobic amino-terminal segment. A strain carrying a null mutation of the sanA gene, transferred to the E. coli chromosome by homologous recombination, is perfectly viable, but after two generations at high temperature (43 degrees C), the barrier function of its envelope towards vancomycin is defective.