Inhibition of Serratia marcescens nuclease secretion by a truncated nuclease peptide.

The production of extracellular nuclease (Nuc) from the Serratia marcescens nucA chromosomal locus is inhibited in cells producing the N-terminal portion of Nuc from a multicopy plasmid. This inhibition in trans is not at the level of nucA expression, but rather at the level of secretion of the Nuc protein. Production of the periplasmic protein beta-lactamase (Bla) does not inhibit Nuc production unless fused to the nucA signal peptide and expressed from nucAp. Inhibition by either the truncated Nuc peptide (delta Nuc) or a Bla fusion protein is promoter specific and observed when expressed from nucAp; little inhibition is observed when the same protein is expressed from the lacZpo promoter-operator. This promoter specificity is also true for the secretion of Nuc itself.