Penicillin-binding proteins of filaments of Escherichia coli induced by low concentrations of nalidixic acid, oxolinic acid, novobiocin or nitrofurantoin.

Nalidixic acid, novobiocin, oxolinic acid and nitrofurantoin, each at low concentrations, cause filamentation of Gram-negative bacilli. Filamentation induced by beta-lactam antibiotics has been correlated to the binding of these antibiotics to specific penicillin-binding proteins (PBPs) of the envelope of Gram-negative bacilli. The studies reported herein indicate that the former group of non-beta-lactam antibiotics do not bind to any of the PBPs of Escherichia coli. However, PBP 1a, PBP 4 and PBP 5/6 of the filaments induced by these agents are increased significantly.