title: Flexibility Analysis of Bacillus thuringiensis Cry1Aa.
abstract: OBJECTIVE
  To investigate the flexibility and mobility of the Bacillus thuringiensis toxin Cry1Aa.
  
  
  METHODS
  The graph theory-based program Constraint Network Analysis and normal mode-based program NMsim were used to analyze the global and local flexibility indices as well as the fluctuation of individual residues in detail.
  
  
  RESULTS
  The decrease in Cry1Aa network rigidity with the increase of temperature was evident. Two phase transition points in which the Cry1Aa structure lost rigidity during the thermal simulation were identified. Two rigid clusters were found in domains I and II. Weak spots were found in C-terminal domain III. Several flexible regions were found in all three domains; the largest residue fluctuation was present in the apical loop2 of domain II.
  
  
  CONCLUSIONS
  Although several flexible regions could be found in all the three domains, the most flexible regions were in the apical loops of domain II.
authors.affiliation: Department of Chemistry and Environmental Engineering, Hunan City University, Yiyang 413000, Hunan, China; Key Laboratory of Microbial Molecular Biology of Hunan Province, College of Life Science, Hunan Normal University, Changsha 410081, Hunan, China.
authors.forename: Xin Min
authors.initials: XM
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Microbial Molecular Biology of Hunan Province, College of Life Science, Hunan Normal University, Changsha 410081, Hunan, China.
authors.forename: Li Qiu
authors.initials: LQ
authors.lastname: Xia
authors.affiliation: Department of Chemistry and Environmental Engineering, Hunan City University, Yiyang 413000, Hunan, China; Division of Medical Oncology, Department of Medicine, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, USA.
authors.forename: Xiao Ping
authors.initials: XP
authors.lastname: Yang
authors.affiliation: Department of Chemistry and Environmental Engineering, Hunan City University, Yiyang 413000, Hunan, China.
authors.forename: Xiao Yun
authors.initials: XY
authors.lastname: Peng
mesh_terms: D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016000:Cluster Analysis; D003198:Computer Simulation; D004731:Endotoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019277:Entropy; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008961:Models, Structural; D009154:Mutation; D011487:Protein Conformation; D058767:Protein Unfolding; D012984:Software; D013696:Temperature
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bacillus thuringiensis; Constraint Network Analysis; Cry1Aa; Flexibility; NMSim