Overlapping motifs on the herpes viral proteins ICP27 and ORF57 mediate interactions with the mRNA export adaptors ALYREF and UIF

Richard B Tunnicliffe,Xiaochen Tian,Rozanne M Sandri-Goldin,Joanna Storer,Alexander P Golovanov

doi:10.1038/s41598-018-33379-x

Richard B Tunnicliffe, Xiaochen Tian + Show 3 more

Open Access

https://doi.org/10.1038/s41598-018-33379-x

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Abstract

The TREX complex mediates the passage of bulk cellular mRNA export to the nuclear export factor TAP/NXF1 via the export adaptors ALYREF or UIF, which appear to act in a redundant manner. TREX complex recruitment to nascent RNA is coupled with 5′ capping, splicing and polyadenylation. Therefore to facilitate expression from their intronless genes, herpes viruses have evolved a mechanism to circumvent these cellular controls. Central to this process is a protein from the conserved ICP27 family, which binds viral transcripts and cellular TREX complex components including ALYREF. Here we have identified a novel interaction between HSV-1 ICP27 and an N-terminal domain of UIF in vivo, and used NMR spectroscopy to locate the UIF binding site within an intrinsically disordered region of ICP27. We also characterized the interaction sites of the ICP27 homolog ORF57 from KSHV with UIF and ALYREF using NMR, revealing previously unidentified binding motifs. In both ORF57 and ICP27 the interaction sites for ALYREF and UIF partially overlap, suggestive of mutually exclusive binding. The data provide a map of the binding sites responsible for promoting herpes virus mRNA export, enabling future studies to accurately probe these interactions and reveal the functional consequences for UIF and ALYREF redundancy.

Highlights

The production of mature messenger RNA in metazoans involves a dynamic series of protein assemblies that orchestrate transcription through to translation
Mutagenesis studies targeting the ksORF57 nuclear localization sequence (NLS) located within the N-terminal intrinsically disordered region (IDR) resulted in weakening of the interaction with ALYREF to background levels without apparently affecting the cellular localization of ksORF5752, which could indicate that this region may contribute to the interaction with ALYREF
In order to explore if messenger RNA (mRNA) export adaptor interaction redundancy is a feature within herpes simplex virus 1 (HSV-1), here we investigated if ICP27 is able to interact with UIF, with our data revealing that these proteins do interact in vivo

Summary

Introduction

The production of mature messenger RNA (mRNA) in metazoans involves a dynamic series of protein assemblies that orchestrate transcription through to translation. The ability to interact with these cellular proteins provides redundancy and likely enhanced efficiency for viral mRNA accumulation and export Such redundancy has not been described for other herpes virus ICP27 homologs to date. Here we used solution NMR to investigate if similar interactions occur between the ksORF57 protein N-terminal IDR, and the cellular proteins ALYREF and UIF, revealing binding sites that in common with ICP27, partially overlap. These data identified new interaction sites for UIF with ICP27 and ksORF57, and an additional ALYREF binding site in the latter. Together our findings indicate that distantly related ICP27 homologs are able to utilize the redundancy present in cellular mRNA export adaptors

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