Protofilament Structure and Supramolecular Polymorphism of Aggregated Mutant Huntingtin Exon 1

JOURNAL OF MOLECULAR BIOLOGY

卷:432

Article

Boatz, Jennifer C.¹  Piretra, Talia¹  Lasorsa, Alessia²  Matlahov, Irina^1,2  Conway, James F.¹  van der Wel, Patrick C. A.^1,2 

[1] Univ Pittsburgh, Sch Med, Dept Struct Biol, 3501 5th Ave,Biomed Sci Tower 3, Pittsburgh, PA 15213 USA

[2] Univ Groningen, Zernike Inst Adv Mat, Nijenborgh 4, NL-9747 AG Groningen, Netherlands

关键词: Huntington's disease;    amyloid;    supramolecular assembly;    TEM;    MAS ssNMR;   

DOI  :  10.1016/j.jmb.2020.06.021

来源: Elsevier

【 摘 要 】

Huntington's disease is a progressive neurodegenerative disease caused by expansion of the polyglutamine domain in the first exon of huntingtin (HttEx1). The extent of expansion correlates with disease progression and formation of amyloid-like protein deposits within the brain. The latter display polymorphism at the microscopic level, both in cerebral tissue and in vitro. Such polymorphism can dramatically influence cytotoxicity, leading to much interest in the conditions and mechanisms that dictate the formation of polymorphs. We examine conditions that govern HttEx1 polymorphism in vitro, including concentration and the role of the non-polyglutamine flanking domains. Using electron microscopy, we observe polymorphs that differ in width and tendency for higher-order bundling. Strikingly, aggregation yields different polymorphs at low and high concentrations. Narrow filaments dominate at low concentrations that may be more relevant in vivo. We dissect the role of N- and C-terminal flanking domains using protein with the former (htt(NT) or N17) largely removed. The truncated protein is generated by trypsin cleavage of soluble HttEx1 fusion protein, which we analyze in some detail. Dye binding and solid-state NMR studies reveal changes in fibril surface characteristics and flanking domain mobility. Higher-order interactions appear facilitated by the C-terminal tail, while the polyglutamine forms an amyloid core resembling those of other polyglutamine deposits. Fibril-surface-mediated branching, previously attributed to secondary nucleation, is reduced in absence of htt(NT). A new model for the architecture of the HttEx1 filaments is presented and discussed in context of the assembly mechanism and biological activity. (C) 2020 The Author(s). Published by Elsevier Ltd.

【 授权许可】

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