Lineage A Betacoronavirus NS2 Proteins and the Homologous Torovirus Berne pp1a Carboxy-Terminal Domain Are Phosphodiesterases That Antagonize Activation of RNase L

Goldstein, Stephen A.; Thornbrough, Joshua M.; Zhang, Rong; Jha, Babal K.; Li, Yize; Elliott, Ruth; Quiroz-Figueroa, Katherine; Chen, Annie I.; Silverman, Robert H.; Weiss, Susan R.

doi:10.1128/jvi.02201-16

Cited by 34 publications

(34 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We previously reported that MERS-CoV NS4b is a member of the 2H-phosphoesterase superfamily of proteins and antagonizes OAS-RNase L activation during MERS-CoV infection through its 2′,5′-PDE activity (19, 29). Unlike previously studied viral PDEs such as mouse hepatitis virus (MHV) NS2, the torovirus pp1a C-terminal domain, and the rotavirus VP3 C-terminal domain, which exhibit primarily cytoplasmic localization (23, 24), NS4b localizes primarily to the nucleus (Fig. 2B), suggesting additional functions.…”

Section: Resultsmentioning

confidence: 69%

“…Our studies of NS4b reveal that in addition to antagonizing OAS-RNase L and preventing NF-κB activation, NS4b antagonizes IFNL1 expression, with this function dependent on both its catalytic activity and nuclear localization and independent of its interaction with the OAS-RNase L pathway. This is a unique role for virus-encoded phosphodiesterases, which otherwise lack an NLS and act solely as OAS-RNase L antagonists (12, 23–26). Together, the results demonstrate that NS4a and NS4b mediate both expected and unexpected functions during MERS-CoV infection and further demonstrate the importance of studying the function of these proteins in the context of infection to uncover the full range of their interactions with the innate immune response.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Antagonism of dsRNA-Induced Innate Immune Pathways by NS4a and NS4b Accessory Proteins during MERS Coronavirus Infection

Comar

Goldstein

et al. 2019

mBio

Self Cite

135

View full text Add to dashboard Cite

Middle East respiratory syndrome coronavirus (MERS-CoV) was first identified in 2012 as a novel etiological agent of severe respiratory disease in humans. As during infection by other viruses, host sensing of viral double-stranded RNA (dsRNA) induces several antiviral pathways. These include interferon (IFN), oligoadenylate synthetase (OAS)-RNase L, and protein kinase R (PKR). Coronaviruses, including MERS-CoV, potently suppress the activation of these pathways, inducing only modest host responses. Our study describes the functions of two accessory proteins unique to MERS-CoV and related viruses, NS4a and NS4b, during infection in human airway epithelium-derived A549 cells. NS4a has been previously characterized as a dsRNA binding protein, while NS4b is a 2′,5′-phosphodiesterase with structural and enzymatic similarity to NS2 encoded by mouse hepatitis virus (MHV). We found that deletion of NS4a results in increased interferon lambda (IFNL1) expression, as does mutation of either the catalytic site or nuclear localization sequence of NS4b. All of the mutant viruses we tested exhibited slight decreases in replication. We previously reported that, like MHV NS2, NS4b antagonizes OAS-RNase L, but suppression of IFN is a previously unidentified function for viral phosphodiesterases. Unexpectedly, deletion of NS4a does not result in robust activation of the PKR or OAS-RNase L pathways. Therefore, MERS-CoV likely encodes other proteins that contribute to suppression or evasion of these antiviral innate immune pathways that should be an important focus of future work. This study provides additional insight into the complex interactions between MERS-CoV and the host immune response. IMPORTANCE Middle East respiratory syndrome coronavirus (MERS-CoV) is the second novel zoonotic coronavirus to emerge in the 21st century and cause outbreaks of severe respiratory disease. More than 2,200 cases and 800 deaths have been reported to date, yet there are no licensed vaccines or treatments. Coronaviruses encode unique accessory proteins that are not required for replication but most likely play roles in immune antagonism and/or pathogenesis. Our study describes the functions of MERS-CoV accessory proteins NS4a and NS4b during infection of a human airway-derived cell line. Loss of these accessory proteins during MERS-CoV infection leads to host antiviral activation and modestly attenuates replication. In the case of both NS4a and NS4b, we have identified roles during infection not previously described, yet the lack of robust activation suggests much remains to be learned about the interactions between MERS-CoV and the infected host.

show abstract

Section: Resultsmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Antagonism of dsRNA-Induced Innate Immune Pathways by NS4a and NS4b Accessory Proteins during MERS Coronavirus Infection

Comar

Goldstein

et al. 2019

mBio

Self Cite

135

View full text Add to dashboard Cite

show abstract

“…Many viruses have evolved specific mechanisms and in some cases specific proteins (coronaviruses, rotaviruses, and Theiler's virus) to evade the antiviral effects of RNase L (35)(36)(37)(38)(39), which we suggest is at least in part because RNase L can be activated even while IFN signaling is antagonized (Fig. 2B) (40).…”

Section: Figmentioning

confidence: 80%

Zika Virus Production Is Resistant to RNase L Antiviral Activity

Whelan

Silverman

et al. 2019

J Virol

Self Cite

View full text Add to dashboard Cite

There is currently no knowledge of how the emerging human pathogen Zika virus (ZIKV) interacts with the antiviral endoribonuclease L (RNase L) pathway during infection. Since activation of RNase L during infection typically limits virus production dramatically, we used CRISPR-Cas9 gene editing technology to knockout (KO) targeted host genes involved in the RNase L pathway to evaluate the effects of RNase L on ZIKV infection in human A549 cells. RNase L was activated in response to ZIKV infection, which degraded ZIKV genomic RNA. Surprisingly, despite viral genome reduction, RNase L activity did not reduce ZIKV infectious titers. In contrast, both the flavivirus dengue virus and the alphavirus Sindbis virus replicated to significantly higher titers in RNase L KO cells compared to wild-type (WT) cells. Using MAVS/RNase L double KO cells, we demonstrated that the absence of increased ZIKV production in RNase L KO cells was not due to compensation by enhanced type I interferon transcripts to thus inhibit virus production. Finally, when synthetic doublestranded RNA was detected by OAS3 to induce RNase L antiviral activity prior to ZIKV infection, we observed reduced ZIKV replication factory formation, as well as a 42-fold reduction in virus yield in WT but not RNase L KO cells. This study proposes that ZIKV evades RNase L antiviral activity by generating a viral genome reservoir protected from RNase L cleavage during early infection, allowing for sufficient virus production before RNase L activation is detectable.

show abstract

“…The binding of 2-5A drives RNase L self-assembly into catalytically active homodimers and high-order oligomers that cleave single-stranded RNA (ssRNA), but not dsRNA molecules inside cells, and exhibit sequence specificity for UN^N sites (m arks the cleavage site; N = A, G, U or C [Han et al 2012[Han et al , 2014Huang et al 2014]). As an arm in the IFN response, RNase L mediates innate immune defense against viruses (Ireland et al 2009;Goldstein et al 2016) and bacteria (Li et al 2008). The functions of RNase L span beyond infection control.…”

Section: Introductionmentioning

confidence: 99%

Rapid RNase L–driven arrest of protein synthesis in the dsRNA response without degradation of translation machinery

Donovan

Rath

Kolet-Mandrikov

et al. 2017

RNA

126

View full text Add to dashboard Cite

Mammalian cells respond to double-stranded RNA (dsRNA) by activating a translation-inhibiting endoribonuclease, RNase L. Consensus in the field indicates that RNase L arrests protein synthesis by degrading ribosomal RNAs (rRNAs) and messenger RNAs (mRNAs). However, here we provide evidence for a different and far more efficient mechanism. By sequencing abundant RNA fragments generated by RNase L in human cells, we identify site-specific cleavage of two groups of noncoding RNAs: Y-RNAs, whose function is poorly understood, and cytosolic tRNAs, which are essential for translation. Quantitative analysis of human RNA cleavage versus nascent protein synthesis in lung carcinoma cells shows that RNase L stops global translation when tRNAs, as well as rRNAs and mRNAs, are still intact. Therefore, RNase L does not have to degrade the translation machinery to stop protein synthesis. Our data point to a rapid mechanism that transforms a subtle RNA cleavage into a cell-wide translation arrest.

show abstract

Lineage A Betacoronavirus NS2 Proteins and the Homologous Torovirus Berne pp1a Carboxy-Terminal Domain Are Phosphodiesterases That Antagonize Activation of RNase L

Cited by 34 publications

References 30 publications

Antagonism of dsRNA-Induced Innate Immune Pathways by NS4a and NS4b Accessory Proteins during MERS Coronavirus Infection

Antagonism of dsRNA-Induced Innate Immune Pathways by NS4a and NS4b Accessory Proteins during MERS Coronavirus Infection

Zika Virus Production Is Resistant to RNase L Antiviral Activity

Rapid RNase L–driven arrest of protein synthesis in the dsRNA response without degradation of translation machinery

Contact Info

Product

Resources

About