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Proc Natl Acad Sci U S A. 2017 Dec 26;114(52):13703-13707. doi: 10.1073/pnas.1713166114. Epub 2017 Dec 4.

Structural studies of Chikungunya virus maturation.

Author information

1
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
2
Department of Biological Science, Faculty of Science, Universiti Tunku Abdul Rahman, 31900 Kampar, Perak, Malaysia.
3
VLP Therapeutics, Gaithersburg, MD 20878.
4
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907; mr@purdue.edu.

Abstract

Cleavage of the alphavirus precursor glycoprotein p62 into the E2 and E3 glycoproteins before assembly with the nucleocapsid is the key to producing fusion-competent mature spikes on alphaviruses. Here we present a cryo-EM, 6.8-Å resolution structure of an "immature" Chikungunya virus in which the cleavage site has been mutated to inhibit proteolysis. The spikes in the immature virus have a larger radius and are less compact than in the mature virus. Furthermore, domains B on the E2 glycoproteins have less freedom of movement in the immature virus, keeping the fusion loops protected under domain B. In addition, the nucleocapsid of the immature virus is more compact than in the mature virus, protecting a conserved ribosome-binding site in the capsid protein from exposure. These differences suggest that the posttranslational processing of the spikes and nucleocapsid is necessary to produce infectious virus.

KEYWORDS:

Chikungunya virus; alphavirus; conformational changes; cryo-electron microscopy; maturation

PMID:
29203665
PMCID:
PMC5748190
DOI:
10.1073/pnas.1713166114
[Indexed for MEDLINE]
Free PMC Article

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