Protein conformation of C9 controls the final membrane complex assembly

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dc.contributor.authorSpicer, BACen_AU
dc.contributor.authorBayly-Jones, Cen_AU
dc.contributor.authorLaw, RHPen_AU
dc.contributor.authorCaradox-Davies, TTen_AU
dc.contributor.authorConroy, PJen_AU
dc.contributor.authorWhisstock, JCen_AU
dc.contributor.authorDunstone, MAen_AU
dc.date.accessioned2021-09-07T22:58:59Zen_AU
dc.date.available2021-09-07T22:58:59Zen_AU
dc.date.issued2017-12-03en_AU
dc.date.statistics2021-08-31en_AU
dc.description.abstractMACPF/CDC pore forming proteins show a unique ability to self-assemble from soluble monomeric proteins into oligomeric rings that change conformation and insert into the target cell membrane. The MACPF/CDC family has been shown to form giant beta-barrel pores that oligomerise, typically using the same unit, and are capable of passive transport of whole soluble proteins across lipid membranes. The current dogma in the field suggests that oligomer assembly is mediated by: 1) increasing the effective concentration on a lipid membrane and, 2) planar diffusion upon the target membrane. However, to date, this model is only consistent with pore forming proteins, such as CDCs and perforin, which have dedicated membrane binding domains that facilitate binding to the membrane surface. In contrast, the proteins of the Membrane Attack Complex (MAC) lack any membrane binding region, which lends it to being able to target a wide range of eukaryotic and bacterial surfaces. However, this precludes the MAC using lateral diffusion for assembly and it is unknown how unwanted solution-based oligomer assembly is avoided. Here we show the first X-ray structure of the soluble C9 component of the MAC and compare this to the near atomic single particle cryo-EM structure of the 22-subunit polyC9. Together these structures show that a 22 amino acid region within the TMH1 loop obstructs oligomer assembly at the oligomer interface. Disulphide trap mutants demonstrate that both TMH1 and TMH2 regions need to move position prior to binding of the next C9 unit in the oligomer assembly pathway. These results challenge the existing dogma in MACPF/CDC pore assembly—that assembly is dependent on increasing the virtual concentration of the protein by membrane binding and requiring lateral diffusion. Instead, movements of the TMH1 and TMH2 of C9 drive MAC assembly. Accordingly, these results explain how the C9 component is able to self-oligomerise into the MAC without the need for lateral diffusion on a membrane and may explain the MAC’s role in assembling on highly variable chemistries at the membrane surface of invading pathogens.en_AU
dc.identifier.citationSpicer, B. A., Bayly-Jones, C., Law, R. H. P., Caradox-Davies, T. T., Conroy, P. J., Whisstock, J. C., & Dunstone, M. A. (2017). Protein conformation of C9 controls the final membrane complex assembly. Paper presented at CRYSTAL 31, the 31st Biennial Conference of the Society of Crystallographers in Australia and New Zealand, Pullman Bunker Bay, Western Australia, 3 – 7 December 2017. Retrieved from: https://crystal31.com/wp-content/uploads/2017/11/SCANZ-Crystal-31-2017-Book-of-Abstracts-FINAL.pdf#page=56en_AU
dc.identifier.conferenceenddate7 December 2017en_AU
dc.identifier.conferencenameCRYSTAL 31, the 31st Biennial Conference of the Society of Crystallographers in Australia and New Zealanden_AU
dc.identifier.conferenceplacePullman Bunker Bay, Western Australiaen_AU
dc.identifier.conferencestartdate3 December 2017en_AU
dc.identifier.urihttps://crystal31.com/wp-content/uploads/2017/11/SCANZ-Crystal-31-2017-Book-of-Abstracts-FINAL.pdf#page=56en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/11618en_AU
dc.language.isoenen_AU
dc.publisherSociety of Crystallographers in Australia and New Zealanden_AU
dc.subjectProteinsen_AU
dc.subjectCell membranesen_AU
dc.subjectLipidsen_AU
dc.subjectDiffusionen_AU
dc.subjectX-ray diffractionen_AU
dc.subjectMembranesen_AU
dc.titleProtein conformation of C9 controls the final membrane complex assemblyen_AU
dc.typeConference Abstracten_AU
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