Combined inactivation of lon and ycgE decreases multidrug susceptibility by reducing the amount of OmpF porin in Escherichia coli.

Transposon inactivation of ycgE, a gene encoding a putative transcriptional regulator, led to decreased multidrug susceptibility in an Escherichia coli lon mutant. The multidrug susceptibility phenotype (e.g., to tetracycline and beta-lactam antibiotics) required the inactivation of both lon and ycgE. In this mutant, a decreased amount of OmpF porin contributes to the lowered drug susceptibility, with a greater effect at 26 degrees C than at 37 degrees C.