PDBsum entry 1t3c

Hydrolase, toxin

PDB id: 1t3c

Contents

Protein chains

411 a.a. *

Metals

_CL ×2

_ZN ×2

Waters ×490

* Residue conservation analysis

PDB id:

1t3c

Name:

Hydrolase, toxin

Title:

Clostridium botulinum type e catalytic domain e212q mutant

Structure:

Neurotoxin type e. Chain: a, b. Fragment: catalytic domain. Engineered: yes. Mutation: yes

Source:

Clostridium botulinum. Organism_taxid: 1491. Strain: nctc-11219. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.90Å R-factor: 0.245 R-free: 0.295

Authors:

R.Agarwal,S.Eswaramoorthy,D.Kumaran,T.Binz,S.Swaminathan

Key ref:

R.Agarwal et al. (2004). Structural analysis of botulinum neurotoxin type E catalytic domain and its mutant Glu212-->Gln reveals the pivotal role of the Glu212 carboxylate in the catalytic pathway. Biochemistry, 43, 6637-6644. PubMed id: 15157097 DOI: 10.1021/bi036278w

Date:

26-Apr-04 Release date: 29-Jun-04

Protein chains

Q00496  (BXE_CLOBO) -  Botulinum neurotoxin type E from Clostridium botulinum

Seq: 1251 a.a.

Struc: 411 a.a.*

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.4.24.69 - bontoxilysin.
• Reaction: Limited hydrolysis of proteins of the neuroexocytosis apparatus, synaptobrevins, SNAP25 or syntaxin. No detected action on small molecule substrates.
• Cofactor: Zn(2+)

DOI no: 10.1021/bi036278w

Biochemistry 43:6637-6644 (2004)

PubMed id: 15157097

Structural analysis of botulinum neurotoxin type E catalytic domain and its mutant Glu212-->Gln reveals the pivotal role of the Glu212 carboxylate in the catalytic pathway.

R.Agarwal, S.Eswaramoorthy, D.Kumaran, T.Binz, S.Swaminathan.

ABSTRACT

The seven serotypes of botulinum neurotoxins (A-G) produced by Clostridium botulinum share significant sequence homology and structural similarity. The functions of their individual domains and the modes of action are also similar. However, the substrate specificity and the peptide bond cleavage selectivity of their catalytic domains are different. The reason for this unique specificity of botulinum neurotoxins is still baffling. If an inhibitor leading to a therapeutic drug common to all serotypes is to be developed, it is essential to understand the differences in their three-dimensional structures that empower them with this unique characteristic. Accordingly, high-resolution structures of all serotypes are required, and toward achieving this goal the crystal structure of the catalytic domain of C. botulinum neurotoxin type E has been determined to 2.1 A resolution. The crystal structure of the inactive mutant Glu212-->Gln of this protein has also been determined. While the overall conformation is unaltered in the active site, the position of the nucleophilic water changes in the mutant, thereby causing it to lose its ability to activate the catalytic reaction. The structure explains the importance of the nucleophilic water and the charge on Glu212. The structural differences responsible for the loss of activity of the mutant provide a common model for the catalytic pathway of Clostridium neurotoxins since Glu212 is conserved and has a similar role in all serotypes. This or a more nonconservative mutant (e.g., Glu212-->Ala) could provide a novel, genetically modified protein vaccine for botulinum.