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Charged Residues in the Membrane Anchor of the Pestiviral Erns Protein Are Important for Processing and Secretion of Erns and Recovery of Infectious Viruses

Institut für Immunologie, Friedrich-Loeffler-Institut, 17493 Greifswald, Germany
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Author to whom correspondence should be addressed.
Current address: CHEPLAPHARM Arzneimittel GmbH, 17489 Greifswald, Germany.
Academic Editor: Helle Bielefeldt-Ohmann
Viruses 2021, 13(3), 444; https://doi.org/10.3390/v13030444
Received: 28 January 2021 / Revised: 2 March 2021 / Accepted: 7 March 2021 / Published: 10 March 2021
(This article belongs to the Section Animal Viruses)
The pestivirus envelope protein Erns is anchored in membranes via a long amphipathic helix. Despite the unusual membrane topology of the Erns membrane anchor, it is cleaved from the following glycoprotein E1 by cellular signal peptidase. This was proposed to be enabled by a salt bridge-stabilized hairpin structure (so-called charge zipper) formed by conserved charged residues in the membrane anchor. We show here that the exchange of one or several of these charged residues reduces processing at the Erns carboxy-terminus to a variable extend, but reciprocal mutations restoring the possibility to form salt bridges did not necessarily restore processing efficiency. When introduced into an Erns-only expression construct, these mutations enhanced the naturally occurring Erns secretion significantly, but again to varying extents that did not correlate with the number of possible salt bridges. Equivalent effects on both processing and secretion were also observed when the proteins were expressed in avian cells, which points at phylogenetic conservation of the underlying principles. In the viral genome, some of the mutations prevented recovery of infectious viruses or immediately (pseudo)reverted, while others were stable and neutral with regard to virus growth. View Full-Text
Keywords: pestivirus; RNA virus polyprotein processing; membrane anchor; charge zipper; amphipathic helix; signal peptidase; secreted T2 RNase pestivirus; RNA virus polyprotein processing; membrane anchor; charge zipper; amphipathic helix; signal peptidase; secreted T2 RNase
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MDPI and ACS Style

Oetter, K.-M.; Kühn, J.; Meyers, G. Charged Residues in the Membrane Anchor of the Pestiviral Erns Protein Are Important for Processing and Secretion of Erns and Recovery of Infectious Viruses. Viruses 2021, 13, 444. https://doi.org/10.3390/v13030444

AMA Style

Oetter K-M, Kühn J, Meyers G. Charged Residues in the Membrane Anchor of the Pestiviral Erns Protein Are Important for Processing and Secretion of Erns and Recovery of Infectious Viruses. Viruses. 2021; 13(3):444. https://doi.org/10.3390/v13030444

Chicago/Turabian Style

Oetter, Kay-Marcus, Juliane Kühn, and Gregor Meyers. 2021. "Charged Residues in the Membrane Anchor of the Pestiviral Erns Protein Are Important for Processing and Secretion of Erns and Recovery of Infectious Viruses" Viruses 13, no. 3: 444. https://doi.org/10.3390/v13030444

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