화학공학소재연구정보센터
Biochemical and Biophysical Research Communications, Vol.435, No.2, 216-221, 2013
Bacillus thuringiensis Cry4Ba toxin employs two receptor-binding loops for synergistic interactions with Cyt2Aa2
We previously demonstrated that co-expression in Escherichia coil of Bacillus thuringiensis (Bt) subsp. israelensis Cry4Ba and Bt subsp. darmstadiensis Cyt2Aa2 shows high synergistic toxicity against target mosquito larvae. Here, further insights into synergistic interactions between these two toxins were revealed through bioactivity restoration of particular inactive Cry4Ba-mutant toxins altered within the receptor-binding domain. Specific mutations at beta 2-beta 3 (Y332A) or beta 4-beta 5 (F364A) loops, but neither at three other beta-hairpin loops (beta 6-beta 7, beta 8-beta 9 and beta 10-beta 11) of Cry4Ba, adversely affect toxicity restoration by Cyt2Aa2. Binding analysis using quartz crystal microbalance verified a decrease in binding of these two bioinactive-mutant toxins (Y332A and F364A) to the immobilized Cyt2Aa2. This suggests that Cry4Ba utilizes these two critical aromatic loop-residues, Tyr(332) and Phe(364), for synergistic toxicity with its alternative receptor-Cyt2Aa2. (c) 2013 Elsevier Inc. All rights reserved.