Complex of Digestive Proteinases of Galleria mellonella Caterpillars. Composition, Properties, and Limited Proteolysis of Bacillus thuringiensis Endotoxins

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N. V. Bulushova¹, E. N. Elpidina^2*, D. P. Zhuzhikov³, L. I. Lyutikova³, F. Ortego⁴, N. E. Kirillova¹, I. A. Zalunin¹, and G. G. Chestukhina¹

¹Scientific Research Institute for Genetics and Selection of Industrial Microorganisms, 1-yi Dorozhnyi Proezd 1, 117545 Moscow, Russia

²Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; fax: (495) 939-3181; E-mail: elp@belozersky.msu.ru

³Biological Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia

⁴Centro de Investigaciones Biologicas, Ramiro de Maeztu 9, 28040 Madrid, Spain

^* To whom correspondence should be addressed.

Received December 27, 2010; Revision received January 31, 2011

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The complex of digestive proteinases in caterpillars of the greater wax moth Galleria mellonella was studied. Using chromogenic substrates and inhibitor analysis, it was found that serine proteinases play a key role in this complex. Three anionic and two cationic forms of trypsin and one anionic and one cationic form of chymotrypsin were identified by zymography in the midgut extract of G. mellonella. The most active trypsin was purified to electrophoretic homogeneity, and its N-terminal amino acid sequence was shown to be identical to that of mature trypsin from Plodia interpunctella. Midgut extract from G. mellonella was capable of processing Cry-proteins from Bacillus thuringiensis ssp. galleriae. Enzymes with tryptic and chymotryptic activities participate in this process, and activation of protoxin Cry9A is not the rate-limiting stage in the toxic action of this protein on the greater wax moth.

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KEY WORDS: Galleria mellonella, insect proteinases, serine proteinases, δ-endotoxins of Bacillus thuringiensis, processing of Cry-toxins

DOI: 10.1134/S0006297911050087

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