Structural basis of complement membrane attack complex formation

Serna, Marina, Giles, Joanna L., Morgan, Bryan Paul ORCID: https://orcid.org/0000-0003-4075-7676 and Bubeck, Doryen 2016. Structural basis of complement membrane attack complex formation. Nature Communications 7 , 10587. 10.1038/ncomms10587

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Abstract

In response to complement activation, the membrane attack complex (MAC) assembles from fluid-phase proteins to form pores in lipid bilayers. MAC directly lyses pathogens by a ‘multi-hit’ mechanism; however, sublytic MAC pores on host cells activate signalling pathways. Previous studies have described the structures of individual MAC components and subcomplexes; however, the molecular details of its assembly and mechanism of action remain unresolved. Here we report the electron cryo-microscopy structure of human MAC at subnanometre resolution. Structural analyses define the stoichiometry of the complete pore and identify a network of interaction interfaces that determine its assembly mechanism. MAC adopts a ‘split-washer’ configuration, in contrast to the predicted closed ring observed for perforin and cholesterol-dependent cytolysins. Assembly precursors partially penetrate the lipid bilayer, resulting in an irregular β-barrel pore. Our results demonstrate how differences in symmetric and asymmetric components of the MAC underpin a molecular basis for pore formation and suggest a mechanism of action that extends beyond membrane penetration.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Medicine
Publisher:	Nature Publishing Group
ISSN:	2041-1723
Date of First Compliant Deposit:	5 July 2017
Date of Acceptance:	31 December 2015
Last Modified:	05 May 2023 07:32
URI:	https://orca.cardiff.ac.uk/id/eprint/102068

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