PDBsum entry: 1ji6

Toxin

PDB id: 1ji6

Contents

Protein chain

589 a.a. *

Waters ×251

* Residue conservation analysis

PDB id:

1ji6

Name:

Toxin

Title:

Crystal structure of the insecticidal bacterial del endotoxin cry3bb1 bacillus thuringiensis

Structure:

Pesticidial crystal protein cry3bb. Chain: a. Fragment: residues 64-652. Synonym: insecticidal delta-endotoxin cryiiib(b), crystaline entomocidal protoxin. Engineered: yes

Source:

Bacillus thuringiensis. Organism_taxid: 1428. Strain: eg7321. Expressed in: escherichia coli. Expression_system_taxid: 562

Biol. unit:

Dimer (from PQS)

Resolution:

2.40Å R-factor: 0.175 R-free: 0.253

Authors:

V.Cody

Key ref:

N.Galitsky et al. (2001). Structure of the insecticidal bacterial delta-endotoxin Cry3Bb1 of Bacillus thuringiensis. Acta Crystallogr D Biol Crystallogr, 57, 1101-1109. PubMed id: 11468393 DOI: 10.1107/S0907444901008186

Date:

29-Jun-01 Release date: 19-Sep-01

Protein chain

Q06117  (CR3BB_BACTU) -  Pesticidal crystal protein cry3Bb

Seq: 652 a.a.

Struc: 589 a.a.

 Gene Ontology (GO) functional annotation 

• Biological process: defense response (3 terms)
• Biochemical function: receptor binding (1 term)

DOI no: 10.1107/S0907444901008186

Acta Crystallogr D Biol Crystallogr 57:1101-1109 (2001)

PubMed id: 11468393

Structure of the insecticidal bacterial delta-endotoxin Cry3Bb1 of Bacillus thuringiensis.

N.Galitsky, V.Cody, A.Wojtczak, D.Ghosh, J.R.Luft, W.Pangborn, L.English.

ABSTRACT

The coleopteran-active delta-endotoxin Cry3Bb1 from Bacillus thuringiensis (Bt) strain EG7231 is uniquely toxic to Diabrotica undecimpunctata, the Southern corn rootworm, while retaining activity against Leptinotarsa decemlineata, the Colorado potato beetle. The crystal structure of the delta-endotoxin Cry3Bb1 has been refined using data collected to 2.4 A resolution, with a residual R factor of 17.5% and an R(free) of 25.3%. The structure is made up of three domains: I, a seven-helix bundle (residues 64-294); II, a three-sheet domain (residues 295-502); and III, a beta-sandwich domain (residues 503-652). The monomers in the orthorhombic C222(1) crystal lattice form a dimeric quaternary structure across a crystallographic twofold axis, with a channel formed involving interactions between domains I and III. There are 23 hydrogen bonds between the two monomers conferring structural stability on the dimer. It has been demonstrated that Cry3Bb1 and the similar toxin Cry3A form oligomers in solution. The structural results presented here indicate that the interactions between domains I and III could be responsible for the initial higher order structure and have implications for the biological activity of these toxins. There are seven additional single amino-acid residues in the sequence of Cry3Bb1 compared with that of Cry3A; one in domain I, two in domain II and four in domain III, which also shows the largest conformational difference between the two proteins. These changes can be implicated in the selectivity differences noted for these two delta-endotoxins.

Selected figure(s)

Figure 1.
Figure 1 (a) Schematic ribbon representation of Cry3Bb1 showing its three-domain organization: domain I (magenta), domain II (cyan) and domain III (green). Loop connections are yellow. The sites of amino-acid insertion in this structure compared with Cry3A are shown in white (domain I, Ala104; domain II, Lys416, Gln453; domain III, Lys554, Leu557, Lys624, Glu626). Diagrams were produced with the program SETOR (Evans, 1993[Evans, S. V. (1993). J. Mol. Graph. 11, 134-138.]). (b). Stereo representation showing an alternate view of Cry3Bb1 highlighting the orientation of the seven-helical bundle of domain I.

Figure 6.
Figure 6 Comparison of the region near the insertion of residue Lys416 in Cry3Bb1 (yellow) with Cry3A (green). This residue points to a hydrophilic pocket with conserved tyrosyl groups.

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2001, 57, 1101-1109) copyright 2001.

Figures were selected by the author.