Production of active Serratia marcescens metalloprotease from Escherichia coli by α-hemolysin HlyB and HlyD

Serratia marcescens produces an abundant extracellular metalloprotease. The gene for this protease had previously been cloned and expressed in Escherichia coli, in which no functional protease could be found. However, the protease gene carries the LXGGXGND repeat motif found in α-hemolysin and other proteins secreted by homologous systems. Using a dual-plasmid complementation system, we show that the α-hemolysin hlyB and hlyD transport determinants are sufficient to allow secretion and activation of a functional metalloprotease species from E. coli, as are the comparable protease secretion functions of Erwinia chrysanthemi. However, strains expressing protease with the hlyBD transport system are unstable and rapidly lose the ability to produce functional protease.