Open AccessB acillus thuringiensis Cry2Ab is active on A nopheles mosquitoes: single D block exchanges reveal critical residues involved in activity
Author(s) -
McNeil Betina C.,
Dean Donald H.
Publication year - 2011
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2011.02403.x
Subject(s) - anopheles gambiae , biology , mutagenesis , bacillus thuringiensis , site directed mutagenesis , lepidoptera genitalia , microbiology and biotechnology , genetics , mutation , gene , botany , bacteria , mutant , immunology , malaria
Cry2Aa exhibits dual activity to L epidoptera and D iptera. Cry2Ab differs in amino acid sequence from Cry2Aa by 13% and has shown significant lepidopteran activity, but no mosquitocidal activity. Previous studies implicate 23 Cry2Aa specificity‐conferring residues of domain II , which differ in Cry2Ab . Nine residues are putatively involved in conferring Cry2Aa dipteran specificity. To explore Cry2Ab dipteran toxicity, site‐directed mutagenesis was employed to exchange Cry2Ab residues with Cry2Aa D (dipteran) block residues. Cry2Ab wild type demonstrated high toxicity ( LC 50 of 540 ng mL −1 ) to A nopheles gambiae , but not to A edes or C ulex , within a 24‐h time period. Cry2Ab should be reclassified as a dual active C ry toxin. Cry2Ab mutagenesis revealed critical residues for Cry2Ab protein function, as well as enhanced activity against the malarial mosquito, A n. gambiae .