Abstract
Most proteins fulfil their function as part of large protein complexes. Surprisingly, little is known about the pathways and regulation of protein assembly. Several viral coat proteins can spontaneously assemble into capsids in vitro with morphologies identical to the native virion and thus resemble ideal model systems for studying protein complex formation. Even for these systems, the mechanism for self-assembly is still poorly understood, although it is generally thought that smaller oligomeric structures form key intermediates. This assembly nucleus and larger viral assembly intermediates are typically low abundant and difficult to monitor. Here, we characterised small oligomers of Hepatitis B virus (HBV) and norovirus under equilibrium conditions using native ion mobility mass spectrometry. This data in conjunction with computational modelling enabled us to elucidate structural features of these oligomers. Instead of more globular shapes, the intermediates exhibit sheet-like structures suggesting that they are assembly competent. We propose pathways for the formation of both capsids.
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Change history
23 July 2014
In the version of this Article originally published, the trace for cp4 was missing from Fig. 3a. This has now been corrected in the online versions of the Article.
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Acknowledgements
The authors thank their collaborators—N.R. Watts, P.T. Wingfield, A.C. Steven, S.E. Crawford, M.K. Estes and B.V. Venkataram Prasad—for providing the viral capsid proteins and helpful discussions. This work was supported by the Netherlands Proteomics Centre, the Natural Sciences and Engineering Research Council through a post-doctoral fellowship grant (to G.K.S.), and by the Netherlands Organisation for Scientific Research (NWO), a VENI (700.58.402) to E.v.D., and an ALW-ECHO (819.02.10) to A.J.R.H. Correspondence and requests for materials should be addressed to A.J.R.H.
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A.J.R.H. and E.v.D. conceived the research. C.U. and G.K.S. conducted the research. I.M.B. performed computational modelling. C.U. analysed the data. C.U. and A.J.R.H. wrote the paper.
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Uetrecht, C., Barbu, I., Shoemaker, G. et al. Interrogating viral capsid assembly with ion mobility–mass spectrometry. Nature Chem 3, 126–132 (2011). https://doi.org/10.1038/nchem.947
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DOI: https://doi.org/10.1038/nchem.947