DIFFERENTIAL-EFFECTS OF HELPER PROTEINS ENCODED BY THE CRY2A AND CRY11A OPERONS ON THE FORMATION OF CRY2A INCLUSIONS IN BACILLUS-THURINGIENSIS

To compare the differential effects of cry2A operon orf2 (29-kDa prote in gene) and Cry11A operon orf3 (20-kDa protein gene) on Cry2A synthes is and inclusion formation, we expressed the cry2A gene along with eit her the 29-kDa gene, 20-kDa gene, or both genes. Constructs containing 20-kDa, in the presence or absence of 29-kDa, produced more Cry2A tha n constructs which lacked this gene. Cry2A synthesis was also higher w hen the 29-kDa gene was included with 20-kDa in the construct. However , even in the presence of increased Cry2A synthesis facilitated by the 20-kDa gene, typical Cry2A crystals did not form if the 29-kDa gene w as not included in the construct. These results suggest that the 29-kD a and 20-kDa proteins have different functions; with the 20-kDa protei n acting like a molecular chaperone to enhance net Cry2A synthesis, an d the 29-kDa protein likely serving as a template for the stabilizatio n of Cry2A molecules and their organization into the rectangular inclu sion characteristic of wild-type Cry2A crystals. (C) 1998 Federation o f European Microbiological Societies. Published by Elsevier Science B. V. All rights reserved.