Isolation, characterization and biological role of camelysin from bacillus thuringiensis subsp. israelensis

Marina Nisnevitch, Sasi Sigawi, Rivka Cahan, Yeshayahu Nitzan

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22 Scopus citations


The present study reports a simple rapid method for isolating the zinc-containing metalloprotease camelysin from Bacillus thuringiensis subsp. israelensis (Bti) by extraction from intact bacterial cells with egg l-α-phosphatidylcholine containing monolamellar liposomes, followed by separation on a sucrose gradient. Characterization of the isolated camelysin revealed a molecular weight of 23 kDa and a pI of 6.2. The camelysin exhibited maximal activity against the substrate azocasein at a temperature of 37°C and pH 7.5. However, the enzyme's activity remained high also at basic pH values (8-10). In a rich growth medium (LB), camelysin appeared at the late logarithmic phase of Bti growth and reached its maximum in the stationary phase. Camelysin was shown to activate the protoxins Cyt1Aa and Cyt2Ba produced by Bti. The hemolytic activity of Cyt1Aa increased from 40 to 70% and that of Cyt2Ba from 6 to 50% in the presence of 50% (w/w) camelysin. It is concluded that these protoxins can be activated not only by insect gut proteases, but also by the endogeneous metalloprotease camelysin of the Bti bacterium.

Original languageEnglish
Pages (from-to)176-183
Number of pages8
JournalCurrent Microbiology
Issue number3
StatePublished - Sep 2010

Bibliographical note

Funding Information:
This research was supported in part by the Samaria and Jordan Rift Valley Regional R&D Center, the Research Authority of the Ariel University Center of Samaria, and the Rappaport Foundation for Medical Microbiology, Bar-Ilan University (to Y.N.).


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