The plasmid F OmpP protease, a homologue of OmpT, as a potential obstacle to E-coli-based protein production

OmpT, an outer membrane-localized protease of Escherichia coli, cleaves a n umber of exogenous and endogenous proteins during their purification. SecY, an endogenous membrane protein, is a target of this artificial proteolysis in vitro. Were we report that SecY cleavage occurs even in cell extracts f rom omp T-disrupted cells, if they carry an F plasmid derivative, A gene, o mpP, On the F plasmid was shown to be responsible for this proteolysis. The se results indicate that the absence of an F-like plasmid should be checked when choosing a host strain for E. coli-based protein production. (C) 1999 Federation of European Biochemical Societies.