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J Struct Biol. 2015 May;190(2):236-49. doi: 10.1016/j.jsb.2015.04.005. Epub 2015 Apr 11.

Characterization of the termini of the West Nile virus genome and their interactions with the small isoform of the 2' 5'-oligoadenylate synthetase family.

Author information

1
Department of Chemistry, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada.
2
School of Biosciences, University of Birmingham, Birmingham B152TT, UK.
3
Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, ul. Ks. Trojdena 4, 02-109 Warsaw, Poland.
4
Department of Chemistry, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada; Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada.
5
Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, ul. Ks. Trojdena 4, 02-109 Warsaw, Poland; Laboratory of Bioinformatics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, ul. Umultowska 89, 61-614 Poznan, Poland.
6
Department of Chemistry, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada; Department of Biochemistry and Medical Genetics, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada. Electronic address: sean.mckenna@umanitoba.ca.

Abstract

2' 5'-Oligoadenylate synthetases (OAS) are interferon-stimulated proteins that act in the innate immune response to viral infection. Upon binding viral double-stranded RNA, OAS enzymes produce 2'-5'-linked oligoadenylates that stimulate RNase L and ultimately slow viral propagation. Truncations/mutations in the smallest human OAS isoform, OAS1, results in susceptibility to West Nile virus (WNV). We have previously demonstrated in vitro the interaction between OAS1 and the 5'-terminal region of the WNV RNA genome. Here we report that the 3'-terminal region is also able to mediate specific interaction with and activation of OAS1. Binding and kinetic experiments identified a specific stem loop within the 3'-terminal region that is sufficient for activation of the enzyme. The solution conformation of the 3'-terminal region was determined by small angle X-ray scattering, and computational models suggest a conformationally restrained structure comprised of a helix and short stem loop. Structural investigation of the 3'-terminal region in complex with OAS1 is also presented. Finally, we show that genome cyclization by base pairing between the 5'- and 3'-terminal regions, a required step for replication, is not sufficient to protect WNV from OAS1 recognition in vitro. These data provide a physical framework for understanding recognition of the highly structured terminal regions of a flaviviral genome by an innate immune enzyme.

KEYWORDS:

Computational structure determination; Oligoadenylate synthetase; RNA–protein interaction; Small angle X-ray scattering; Terminal region; West Nile virus

PMID:
25871524
DOI:
10.1016/j.jsb.2015.04.005
[Indexed for MEDLINE]

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