Department of Biology, Texas A & M University, College Station 77843-3258.
Utilizing the DNA sequence of the metalloprotease from Serratia strain E-15, we isolated and sequenced the homologous gene from Serratia strain SM6. These two genes are similar at both the DNA and protein sequence level. Expression of the protease gene in Escherichia coli was achieved by use of the lac promoter. This resulted in the production and excretion of an immunologically detectable but inactive protein of slightly higher molecular weight than that from Serratia. We introduced the cloned gene into previously described protease mutants. The observed pattern of protease expression suggested that these mutations fall into three classes.