Modified Cry1Ca insecticial Cry proteins
View Patent ↗The present invention includes modified, insecticidal B.t. Cry1Ca proteins, including the proteins designated herein as DIG-109 and DIG-152, as well as variants of DIG-109 and DIG-152, nucleic acids encoding these proteins, methods of controlling pests using the proteins, methods of producing the proteins in transgenic host cells, and transgenic plants that produce the proteins. The DIG-109 and DIG-152 proteins comprise chimeric peptides composed of a core toxin segment of B.t. Cry1Ca and a Cry1Ab protoxin segment. Insecticidally active variants of the DIG-109 and DIG-152 proteins are also described.
1. A Cry1Ca variant protein that has insecticidal activity, in which all or part of N-terminal alpha helices 1, 2A, and/or 2B of a corresponding wild-type Cry1Ca are deleted, wherein said protein is at least 99% identical to a sequence selected from the group consisting of: SEQ ID NO: 3 and SEQ ID NO:5.
2. The variant protein of claim 1 wherein deletions remove all of α-helix 1 and all or part of α-helix 2 in Domain I, said protein comprising α-helices 3 through 7.
3. The variant protein of claim 1 wherein said deletions improve insecticidal activity of insecticidal protein DIG-109, wherein said deletions initiate before α-helix 2A start and terminate after α-helix 2B end but do not extend into α-helix 3.
4. The variant protein of claim 1 wherein said deletions improve insecticidal activity of insecticidal protein DIG-152, wherein said deletions initiate before α-helix 2A start and terminate after α-helix 2B end but do not extend into α-helix 3.
5. The variant protein of claim 1 wherein N-terminal deletions begin with at least one destabilizing amino acids, and said protein comprises an added codon that specifies a glycine amino acid between a translational initiation methionine and the destabilizing amino acid.
6. The variant protein of claim 1 wherein said protein lacks C-terminal protoxin sequence.
7. The protein of claim 1 , wherein said protein has improved activity against an insect compared to the wild-type Cry1Ca protein.
8. The protein of claim 7 wherein said insect is selected from the group consisting of fall armyworm and sugarcane borer.
9. The protein of claim 1 , wherein said protein is at least 99% identical to SEQ ID NO:3.
10. The protein of claim 1 , wherein said protein is at least 99% identical to SEQ ID NO:5.
11. The protein of claim 9 , wherein said protein comprises SEQ ID NO:3.
12. The protein of claim 10 , wherein said protein comprises SEQ ID NO:5.