Building-block architecture of botulinum toxin complex: Conformational changes provide insights into the hemagglutination ability of the complex

Tomonori Suzuki; Yoshimasa Sagane; Takashi Matsumoto; Kimiko Hasegawa; Akihito Yamano; Koichi Niwa; Toshihiro Watanabe

doi:10.1016/j.bbrep.2016.11.008

Building-block architecture of botulinum toxin complex: Conformational changes provide insights into the hemagglutination ability of the complex

Biochem Biophys Rep. 2016 Nov 19:9:67-71. doi: 10.1016/j.bbrep.2016.11.008. eCollection 2017 Mar.

Authors

Tomonori Suzuki¹, Yoshimasa Sagane², Takashi Matsumoto³, Kimiko Hasegawa³, Akihito Yamano³, Koichi Niwa², Toshihiro Watanabe²

Affiliations

¹ Department of Nutritional Science and Food Safety, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
² Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan.
³ Rigaku Corporation, 3-9-12 Matsubara-Cho, Akishima 196-8666, Japan.

Abstract

Clostridium botulinum produces the botulinum neurotoxin (BoNT). Previously, we provided evidence for the "building-block" model of botulinum toxin complex (TC). In this model, a single BoNT is associated with a single nontoxic nonhemagglutinin (NTNHA), yielding M-TC; three HA-70 molecules are attached and form M-TC/HA-70, and one to three "arms" of the HA-33/HA-17 trimer (two HA-33 and one HA-17) further bind to M-TC/HA-70 via HA-17 and HA-70 binding, yielding one-, two-, and three-arm L-TC. Of all TCs, only the three-arm L-TC caused hemagglutination. In this study, we determined the solution structures for the botulinum TCs using small-angle X-ray scattering (SAXS). The mature three-arm L-TC exhibited the shape of a "bird spreading its wings", in contrast to the model having three "arms", as revealed by transmission electron microscopy. SAXS images indicated that one of the three arms of the HA-33/HA-17 trimer bound to both HA-70 and BoNT. Taken together, these findings regarding the conformational changes in the building-block architecture of TC may explain why only three-arm L-TC exhibited hemagglutination.

Keywords: BoNT, botulinum neurotoxin; Botulinum neurotoxin; DAM, dummy atom model; HA, hemagglutinin; Hemagglutination; NTNHA, nontoxic nonhemagglutinin; QCM, quartz crystal microbalance; SAXS, small-angle X-ray scattering; SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis; Small-angle X-ray scattering; TC, toxin complex; TEM, transmission electron microscopy.