Purification, bacteriolytic activity, and specificity of β-lytic protease fromLysobacter sp. IB-9374

Abstract

Lysobacter sp. IB-9374, which was isolated from soil as a high lysyl endopeptidase-producing strain (Chohnanet al., FEMS Microbiol. Lett., 213, 13–20, 2002), was found to produce a β-lytic protease capable of lysing gram-positive bacteria such asStaphylococcus aureus, Microccocuseus, andBacillus subtilis. The Lysobacter strain secreted the β-lytic protease into the culture medium at a 2.4-fold higher level thanAchromobacter lyticus. The enzyme was highly purified through a series of six steps with a high yield. The enzyme was strongly inhibited by tetraethylene-pentamine and 1,10-phenanthroline. The purified enzyme lysed more efficiently almost all the gram-positive bacteria tested than lysozyme, lysostaphin, and mutanolysin. The enzyme was very similar toAchromobacter β-lytic protease containing one zinc atom in terms of amino acid composition and N-terminal sequence. The nucleotide sequence revealed that the mature enzyme was composed of 179 amino acid residues with additional 198 amino acids at the amino-terminal end of the enzyme. The deduced amino acid sequence of the mature enzyme coincided with that of theAchromobacter enzyme, although the prepro-region showed a 41% sequence identity with the counterpart. These results indicate thatLysobacter sp. is a useful strain for an efficient large-scale preparation of β-lytic protease capable of lysing bacteria.