Structural And Biochemical Studies of Botulinum Neurotoxin Serotype C1 Light Chain Protease: Implications for Dual Substrate Specificity

Journal Article · Mon Jun 01 04:00:00 EDT 2009 · Biochem. 46:10685,2007

OSTI ID:953998

Jin, R; Sikorra, S; Stegmann, C M; Pich, A; Binz, T; Brunger, A T

Clostridial neurotoxins are the causative agents of the neuroparalytic disease botulism and tetanus. They block neurotransmitter release through specific proteolysis of one of the three soluble N-ethylmaleimide-sensitive-factor attachment protein receptors (SNAREs) SNAP-25, syntaxin, and synaptobrevin, which constitute part of the synaptic vesicle fusion machinery. The catalytic component of the clostridial neurotoxins is their light chain (LC), a Zn2+ endopeptidase. There are seven structurally and functionally related botulinum neurotoxins (BoNTs), termed serotype A to G, and tetanus neurotoxin (TeNT). Each of them exhibits unique specificity for their target SNAREs and peptide bond(s) they cleave. The mechanisms of action for substrate recognition and target cleavage are largely unknown. Here, we report structural and biochemical studies of BoNT/C1-LC, which is unique among BoNTs in that it exhibits dual specificity toward both syntaxin and SNAP-25. A distinct pocket (S1') near the active site likely achieves the correct register for the cleavage site by only allowing Ala as the P1' residue for both SNAP-25 and syntaxin. Mutations of this SNAP-25 residue dramatically reduce enzymatic activity. The remote a-exosite that was previously identified in the complex of BoNT/A-LC and SNAP-25 is structurally conserved in BoNT/C1. However, mutagenesis experiments show that the a-exosite of BoNT/C1 plays a less stringent role in substrate discrimination in comparison to that of BoNT/A, which could account for its dual substrate specificity.

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 953998
• Report Number(s): SLAC-REPRINT-2009-394
• Journal Information: Biochem. 46:10685,2007, Journal Name: Biochem. 46:10685,2007 Journal Issue: 37 Vol. 46; ISSN 0006-2960; ISSN BICHAW
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
CLEAVAGE
CLOSTRIDIUM BOTULINUM
DISEASES
MUTAGENESIS
MUTATIONS
Other
BIO
CHEM
PEPTIDES
POLYPEPTIDES
PROTEINS
PROTEOLYSIS
RECEPTORS
RESIDUES
SPECIFICITY
SUBSTRATES
TETANUS
TOXINS