title: Residue 544 in domain III of the Bacillus thuringiensis Cry1Ac toxin is involved in protein structure stability.
abstract: A unique residue W544 in the beta18-beta19 loop of the Bacillus thuringiensis Cry1Ac toxin has been implicated in its toxicity. In this study, the effects of mutations at this residue on protein stability during protease treatment, UV irradiation, and preservation were examined. Residue 544 of Cry1Ac was involved in maintaining structural stability, and substitution of a polar group at this position was unfavorable to protein stability. One mutant, W544F, produced larger crystals and was more stable. This mutant showed greater resistance to UV radiation than the wild type Cry1Ac but retained equal toxicity. This is the first report showing that residue 544 in the Cry1Ac domain III plays a significant role in toxin structural stability. Our W544F mutant is a significant development in terms of field applications of Cry1Ac toxin.
authors.affiliation: College of Chemistry and Bioengineering, Changsha University of Science and Technology, 410004 Changsha, China.
authors.forename: Yong Le
authors.initials: YL
authors.lastname: Liu
authors.forename: Qin Yun
authors.initials: QY
authors.lastname: Wang
authors.forename: Fa Xiang
authors.initials: FX
authors.lastname: Wang
authors.forename: Xue Zhi
authors.initials: XZ
authors.lastname: Ding
authors.forename: Li Qiu
authors.initials: LQ
authors.lastname: Xia
mesh_terms: D001413:Bacillus thuringiensis / Q000737:chemistry* / Q000378:metabolism; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004731:Endotoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D009154:Mutation; D055550:Protein Stability; D017434:Protein Structure, Tertiary
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis