Crystal Structure of the Botulinum Neurotoxin Type G Binding Domain: Insight into Cell Surface Binding

JOURNAL OF MOLECULAR BIOLOGY

卷:397

Article

Stenmark, Pal^2,3  Dong, Min^1,4,5  Dupuy, Jerome²  Chapman, Edwin R.^1,4  Stevens, Raymond C.² 

[1] Univ Wisconsin, Howard Hughes Med Inst, Madison, WI 53706 USA

[2] Scripps Res Inst, Dept Mol Biol, La Jolla, CA 92037 USA

[3] Stockholm Univ, Ctr Biomembrane Res, Dept Biochem & Biophys, SE-10691 Stockholm, Sweden

[4] Univ Wisconsin, Dept Physiol, Madison, WI 53706 USA

[5] Harvard Univ, Sch Med, New England Primate Res Ctr, Dept Microbiol & Mol Genet, Southborough, MA 01772 USA

关键词: botulinum;    neurotoxin;    synaptotagmin;    ganglioside;    toxin;   

DOI  :  10.1016/j.jmb.2010.02.041

来源: Elsevier

【 摘 要 】

Botulinum neurotoxins (BoNTs) typically bind the neuronal cell surface via dual interactions with both protein receptors and gangliosides. We present here the 1.9-angstrom X-ray structure of the BoNT serotype G (BoNT/G) receptor binding domain (residues 868-1297) and a detailed view of protein receptor and ganglioside binding regions. The ganglioside binding motif (SxWY) has a conserved structure compared to the corresponding regions in BoNT serotype A and BoNT serotype B (BoNT/B), but several features of interactions with the hydrophilic face of the ganglioside are absent at the opposite side of the motif in the BoNT/G ganglioside binding cleft. This may significantly reduce the affinity between BoNT/G and gangliosides. BoNT/G and BoNT/B share the protein receptor synaptotagmin (Syt) I/II. The Syt binding site has a conserved hydrophobic plateau located centrally in the proposed protein receptor binding interface (Tyr1189, Phe1202, Ala1204, Pro1205, and Phe1212). Interestingly, only 5 of 14 residues that are important for binding between Syt-II and BoNT/B are conserved in BoNT/G, suggesting that the means by which BoNT/G and BoNT/B bind Syt diverges more than previously appreciated. Indeed, substitution of Syt-II Phe47 and Phe55 with alanine residues had little effect on the binding of BoNT/G, but strongly reduced the binding of BoNT/B. Furthermore, an extended solvent-exposed hydrophobic loop, located between the Syt binding site and the ganglioside binding cleft, may serve as a third membrane association and binding element to contribute to high-affinity binding to the neuronal membrane. While BoNT/G and BoNT/B are homologous to each other and both utilize Syt-I/Syt-II as their protein receptor, the precise means by which these two toxin serotypes bind to Syt appears surprisingly divergent. (C) 2010 Published by Elsevier Ltd.

【 授权许可】

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