Genes encoding proteins with pesticidal activity

Abstract

The invention provides nucleic acids, and variants and fragments thereof, obtained from strains of Bacillus thuringiensis encoding δ-endotoxins having pesticidal activity against insect pests. The invention further provides mutagenized nucleic acids that have been modified to encode pesticidal polypeptides such as endotoxins having improved pesticidal activity and/or altered pest specificity. Particular embodiments of the invention provide isolated nucleic acids encoding pesticidal proteins that may be optimized as well as pesticidal compositions, expression cassettes, and transformed microorganisms and plants comprising a nucleic acid of the invention. These compositions find use in methods for controlling pests, especially plant pests.

1 . An endotoxin comprising a mutation consisting of the alteration of at least one proteolytic site, whereby the stability of the endotoxin in an insect gut is increased relative to an endotoxin lacking said mutation.  
     
     
         2 . The endotoxin of  claim 1 , wherein said mutation consists of an alteration selected from the group consisting of: 
 a) an addition of at least one amino acid to at least one proteolytic site;    b) a removal of at least one amino acid from at least one proteolytic site;    c) a replacement of at least one amino acid of at least one proteolytic site with a different amino acid; and    d) a combination of at least two of (a), (b), and (c).    
     
     
         3 . The endotoxin of  claim 2 , wherein said mutation consists of an alteration which is the replacement of at least one amino acid of a proteolytic site with an amino acid selected from the group consisting of valine and arginine.  
     
     
         4 . The endotoxin of  claim 1 , wherein at least one of said at least one proteolytic sites is a trypsin site.  
     
     
         5 . The endotoxin of  claim 1 , wherein at least one of said at least one proteolytic sites is a chymotrypsin site.  
     
     
         6 . The endotoxin of  claim 1 , wherein at least one of said at least one proteolytic sites is a cathepsin site.  
     
     
         7 . The endotoxin of  claim 1 , further comprising at least one engineered cathepsin-sensitive proteolytic site, wherein said endotoxin has improved pesticidal activity relative to an endotoxin which lacks said at least one cathepsin-sensitive proteolytic site.