Coat Protein Regulation by CK2, CPIP, HSP70, and CHIP Is Required for Potato Virus A Replication and Coat Protein Accumulation

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Lohmus , A , Hafren , A & Mäkinen , K 2017 , ' Coat Protein Regulation by CK2, CPIP, HSP70, and CHIP Is Required for Potato Virus A Replication and Coat Protein Accumulation ' , Journal of Virology , vol. 91 , no. 3 , 01316 . https://doi.org/10.1128/JVI.01316-16

Title: Coat Protein Regulation by CK2, CPIP, HSP70, and CHIP Is Required for Potato Virus A Replication and Coat Protein Accumulation
Author: Lohmus, Andres; Hafren, Anders; Mäkinen, Kristiina
Contributor organization: University of Helsinki
Department of Food and Nutrition
Plant-Virus Interactions
Viikki Plant Science Centre (ViPS)
Date: 2017-02
Language: eng
Number of pages: 14
Belongs to series: Journal of Virology
ISSN: 0022-538X
DOI: https://doi.org/10.1128/JVI.01316-16
URI: http://hdl.handle.net/10138/297824
Abstract: We demonstrate here that both coat protein (CP) phosphorylation by protein kinase CK2 and a chaperone system formed by two heat shock proteins, CP-interacting protein (CPIP) and heat shock protein 70 (HSP70), are essential for potato virus A (PVA; genus Potyvirus) replication and that all these host proteins have the capacity to contribute to the level of PVA CP accumulation. An E3 ubiquitin ligase called carboxyl terminus Hsc70-interacting protein (CHIP), which may participate in the CPIP-HSP70-mediated CP degradation, is also needed for robust PVA gene expression. Residue Thr243 within the CK2 consensus sequence of PVA CP was found to be essential for viral replication and to regulate CP protein stability. Substitution of Thr243 either with a phosphorylation-mimicking Asp (CPADA) or with a phosphorylation-deficient Ala (CPAAA) residue in CP expressed from viral RNA limited PVA gene expression to the level of nonreplicating PVA. We found that both the CPAAA mutant and CK2 silencing inhibited, whereas CPADA mutant and overexpression of CK2 increased, PVA translation. From our previous studies, we know that phosphorylation reduces the RNA binding capacity of PVA CP and an excess of CP fully blocks viral RNA translation. Together, these findings suggest that binding by nonphosphorylated PVA CP represses viral RNA translation, involving further CP phosphorylation and CPIP-HSP70 chaperone activities as prerequisites for PVA replication. We propose that this mechanism contributes to shifting potyvirus RNA from translation to replication. IMPORTANCE Host protein kinase CK2, two host chaperones, CPIP and HSP70, and viral coat protein (CP) phosphorylation at Thr243 are needed for potato virus A (PVA) replication. Our results show that nonphosphorylated CP blocks viral translation, likely via binding to viral RNA. We propose that this translational block is needed to allow time and space for the formation of potyviral replication complex around the 3' end of viral RNA. Progression into replication involves CP regulation by both CK2 phosphorylation and chaperones CPIP and HSP70.
Subject: E3 ubiquitin ligase CHIP
HSP70
potato virus A
potyvirus
coat protein
heat shock protein HSP40
protein kinase CK2
translation
viral replication
MAJOR PHOSPHORYLATION SITES
DEPENDENT RNA-POLYMERASE
E3 UBIQUITIN LIGASE
CAPSID PROTEIN
VIRAL REPLICATION
MULTIPLE FUNCTIONS
CORE PROTEIN
TRANSLATION
INFECTION
BINDING
1183 Plant biology, microbiology, virology
Peer reviewed: Yes
Usage restriction: openAccess
Self-archived version: acceptedVersion


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