Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.27 (thermolysin)
 1,894 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Clostridal neurotoxins (CNTs) are the causative agents of the neuroparalytic diseases botulism and tetanus. CNTs impair neuronal exocytosis through specific proteolysis of essential proteins called SNAREs. SNARE assembly into a low-energy ternary complex is believed to catalyse membrane fusion, precipitating neurotransmitter release; this process is attenuated in response to SNARE proteolysis. Site-specific SNARE hydrolysis is catalysed by the CNT light chains, a unique group of zinc-dependent endopeptidases. The means by which a CNT properly identifies and cleaves its target SNARE has been a subject of much speculation; it is thought to use one or more regions of enzyme-substrate interaction remote from the active site (exosites). Here we report the first structure of a CNT endopeptidase in complex with its target SNARE at a resolution of 2.1 A: botulinum neurotoxin serotype A (BoNT/A) protease bound to human SNAP-25. The structure, together with enzyme kinetic data, reveals an array of exosites that determine substrate specificity. Substrate orientation is similar to that of the general zinc-dependent metalloprotease thermolysin. We observe significant structural changes near the toxin's catalytic pocket upon substrate binding, probably serving to render the protease competent for catalysis. The novel structures of the substrate-recognition exosites could be used for designing inhibitors specific to BoNT/A.
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PMID:Substrate recognition strategy for botulinum neurotoxin serotype A. 1559 54

TeNT is the causative agent of the neuroparalytic disease tetanus. A key component of TeNT is its light chain, a Zn(2+) endopeptidase that targets SNAREs. Recent structural studies of closely related BoNT endopeptidases indicate that substrate-binding exosites remote from a conserved active site are the primary determinants of substrate specificity. Here we report the 2.3 A X-ray crystal structure of TeNT-LC, determined by combined molecular replacement and MAD phasing. As expected, the overall structure of TeNT-LC is similar to the other known CNT light chain structures, including a conserved thermolysin-like core inserted between structurally distinct amino- and carboxy-terminal regions. Differences between TeNT-LC and the other CNT light chains are mainly limited to surface features such as unique electrostatic potential profiles. An analysis of surface residue conservation reveals a pattern of relatively high variability matching the path of substrate binding around BoNT/A, possibly serving to accommodate the variations in different SNARE targets of the CNT group.
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PMID:2.3 A crystal structure of tetanus neurotoxin light chain. 1589 88