Insights from the Structure of an Active Form of Bacillus thuringiensis Cry5B

• Published in: Toxins Vol. 14; no. 12; p. 823
• Main Authors: Li, Jiaxin, Wang, Lin, Kotaka, Masayo, Lee, Marianne M, Chan, Michael K
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 23-11-2022; MDPI
• Subjects: Amino acids; Antiparasitic agents; Bacillus thuringiensis; Bacillus thuringiensis - metabolism; Bacillus thuringiensis Toxins - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Binding sites; Computer applications; Cry5B; Crystal proteins; crystal structure; Domains; E coli; Endotoxins - metabolism; Hemolysin Proteins - metabolism; Infections; nematicidal activity; Nematodes; oligomerization; Pore formation; Protein structure; Proteins; Quaternary structure; Random coil; Residues; Site-directed mutagenesis; Soil bacteria; Soil microorganisms; Toxicity; crystal structure; Cry5B; oligomerization; nematicidal activity
• ISSN: 2072-6651; 2072-6651
• DOI: 10.3390/toxins14120823

The crystal protein Cry5B, a pore-forming protein produced by the soil bacterium
, has been demonstrated to have excellent anthelmintic activity. While a previous structure of the three-domain core region of Cry5B(112-698) had been reported, this structure lacked a key N-terminal extension critical to function. Here we report the structure of Cry5B(27-698) containing this N-terminal extension. This new structure adopts a distinct quaternary structure compared to the previous Cry5B(112-698) structure, and also exhibits a change in the conformation of residues 112-140 involved in linking the N-terminal extension to the three-domain core by forming a random coil and an extended α-helix. A role for the N-terminal extension is suggested based on a computational model of the tetramer with the conformation of residues 112-140 in its alternate α-helix conformation. Finally, based on the Cry5B(27-698) structure, site-directed mutagenesis studies were performed on Tyr495, which revealed that having an aromatic group or bulky group at this residue 495 is important for Cry5B toxicity.