Lysobacter strain with high lysyl endopeptidase production.

ABSTRACT

A new lysyl endopeptidase producing strain, Lysobacter sp. IB-9374, was isolated from soil. This strain secreted the endopeptidase to culture medium at 6-12-fold higher levels relative to Achromobacter lyticus and Lysobacter enzymogenes. The mature Lysobacter sp. enzyme was enzymatically identical to Achromobacter lysyl endopeptidase bearing lysyl bond specificity, a high peptidase activity, a wide pH optimum, and stability against denaturants. Nucleotide sequence analysis of the Lysobacter sp. lysyl endopeptidase gene revealed that the enzyme is synthesized as a precursor protein consisting of signal peptide (20 amino acids (aa)), pro-peptide (185 aa), mature enzyme (268 aa), and C-terminal extension peptide (198 aa). The deduced amino acid sequence of the mature enzyme was totally identical to that of the Achromobacter enzyme. The Lysobacter sp. precursor protein has an 18-aa longer peptide chain following nine consecutive amino acid residues distinct from the Achromobacter counterpart at the C-terminus. Total precursor protein is 671 aa of which only 268 aa are in the finally processed exoenzyme.