Increasing the rate of cleavage at the boundary between non-structural protein 4B and 5A inhibits replication of hepatitis C virus

Herod, Morgan R., Jones, Daniel M., McLauchlan, John and McCormick, Christopher J. (2011) Increasing the rate of cleavage at the boundary between non-structural protein 4B and 5A inhibits replication of hepatitis C virus. Journal of Biological Chemistry, 287, 568-580. (doi:10.1074/jbc.M111.311407).


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In hepatitis C virus, non-structural proteins are cleaved from the viral polyprotein by viral encoded proteases. While proteolytic processing goes to completion, the rate of cleavage differs between different boundaries, primarily due to the sequence at these positions. However it is not known whether slow cleavage is important for viral replication, or a consequence of restrictions on sequences which can be tolerated at the cleaved ends of non-structural
proteins. To address this question, mutations were introduced into the NS4B side of the NS4B5A boundary and their effect on replication and polyprotein processing examined in the context of a subgenomic replicon. Single mutations that modestly increased the rate of boundary processing were phenotypically silent, but a double mutation, which further increased the rate of boundary cleavage, was lethal. Rescue experiments relying on viral RNA polymerase-induced error failed to identify second site compensatory mutations. Use of a replicon library with codon
degeneracy did allow identification of second site compensatory mutations, some of which fell exclusively within the NS5A side of the boundary. These mutations slowed boundary cleavage and only enhanced replication in the context of the original lethal NS4B double mutation. Overall the data indicate that slow cleavage of the NS4B5A boundary is important, and identify a previously unrecognised role for NS4B5A-containing precursors requiring them to exist for a minimum finite period of time.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1074/jbc.M111.311407
ISSNs: 0021-9258 (print)
1083-351X (electronic)
Alternative titles: Increasing rate of NS4B5A cleavage inhibits HCV replication
Related URLs:
Subjects: Q Science > QR Microbiology > QR355 Virology
R Medicine > R Medicine (General)
Divisions : Faculty of Medicine > Clinical and Experimental Sciences
ePrint ID: 203337
Accepted Date and Publication Date:
14 November 2011Made publicly available
Date Deposited: 15 Nov 2011 12:14
Last Modified: 31 Mar 2016 13:46
Temporal and co-ordinated processing of the Hepatitis C virus polyprotein as an important determinant of viral fitness
Funded by: MRC (G0701215)
Led by: Christopher McCormick
3 November 2008 to 2 May 2012

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