Crystal structure of BinB: A receptor binding component of the binary toxin from Lysinibacillus sphaericus

Abstract

The binary toxin (Bin), produced by Lysinibacillus sphaericus, is composed of BinA (42 kDa) and BinB (51 kDa) proteins, which are both required for full toxicity against Culex and Anopheles mosquito larvae. Specificity of Bin toxin is determined by the binding of BinB component to a receptor present on the midgut epithelial membranes, while BinA is proposed to be a toxic component. Here, we determined the first crystal structure of the active form of BinB at a resolution of 1.75 Å. BinB possesses two distinct structural domains in its N- and C-termini. The globular N-terminal domain has a β-trefoil scaffold which is a highly conserved architecture of some sugar binding proteins or lectins, suggesting a role of this domain in receptor-binding. The BinB β-rich C-terminal domain shares similar three-dimensional folding with aerolysin type β-pore forming toxins, despite a low sequence identity. The BinB structure, therefore, is a new member of the aerolysin-like toxin family, with probably similarities in the cytolytic mechanism that takes place via pore formation.

Structural classification of insecticidal proteins – Towards an in silico characterisation of novel toxins

“…Binding of BinB to target membranes appears to be mediated by residues at its N-terminal end (Oei et al, 1992;Romao et al, 2011;Singkhamanan et al, 2010), consistent with receptor recognition via the head domain (Srisucharitpanit et al, 2014). The BinA/BinB toxin appears to bind to a single toxin receptor, a GPI anchored -glycosidase (Silva-Filha et al, 1999), which may simplify the investigation of binding interactions (particularly when compared to the complex receptor binding of 3-domain toxins).…”

“…Cry21 The structures of the insecticidal toxins BinB (PDB 3WA1 (Srisucharitpanit et al, 2014)), Cry35 (PDB 4JP0 (Kelker et al, 2014)), Cry23 (PDB 4RHZ), Cry45 (PDB 2D42 (Akiba et al, 2006)), Cry46 (PDB 2ZTB (Akiba et al, 2009)) and Cry51 (PDB 4PKM (Xu et al, 2015)) are…”

Mechanism of action of Bacillus thuringiensis insecticidal toxins and their use in the control of insect pests

“…The structure of both proteins has been solved (PDB: 4JP0 and 4JOX) ( Figure 30.2). Cry35 has two domains mainly composed of β-strands and small α-helices; this protein shows similarities (Pfam0531) with BinB toxin from L. sphaericus classified as the receptor binding component of the binary toxin (PDB 3WA1) [10]. Figure 30.2 shows the structure alignment of domain 2 of Cry35A with BinB toxin using the jFAT-CAT algorithm [14].…”

“…This family of proteins are named Bin-like since they share some similarities with the dipteran-specific binary toxins (Bin) produced by Lysinibacillus sphaericus [9,10]. Two groups of proteins, Cry35 and Cry36, form part of the Bin-like Cry family.…”

Modelos caracterizando a interação entre as toxinas da família Cry1A de Bacillus thuringiensis e o receptor BT-R1 de Manduca sexta

“…et al, 2008;Kelker, M.S. et al, 2014;Popoff, M.R., 2011;Srisucharitpanit, K. et al, 2014). (Ohba, M., Mizuki, E. & Uemori, A., 2009;Xu, C. et al, 2014).…”