Molecular Analysis of the Gene Encoding Alpha-lytic Protease: Evidence for a Preproenzyme

A 1.7-kb EcoRI fragment containing the structural gene for alpha-lytic protease has been cloned from Lysobacter enzymogenes 495 chromosomal DNA: the first example of a gene cloned from this organism. The protein sequence deduced from the nucleotide sequence encoding this serine protease matches the published amino acid sequence [Olson et al., Nature 228 (1970) 438-442] precisely. Sequence analysis and S1 mapping indicate that, like subtilisin [e.g., Wells et al., Nucleic Acids Res. 11 (1983) 7911-7925] alpha-lytic protease is synthesized as a pre-pro protein (41 kDa) that is subsequently processed to its mature extracellular form (20 kDa). This first finding of a large N-terminal protease precursor in a Gram-negative bacterial protease strengthens the hypothesis that large precursors may be a general property of extracellular bacterial proteases, and suggests that the N- or C-terminal location of the precursor segment may be significant.