The Potential for m6A RNA Methylation Research of SARS-CoV-2
(2019 Novel Coronavirus)

Viruses have been capturing media headlines of late due to the recent pandemic concern of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), the RNA virus that causes COVID-19 (Coronavirus Disease 2019). Post-transcriptional modifications are known to play important roles in the life cycles of certain viruses like human coronavirus.

Adenosine methylation in particular, such as m6A, m6Am, and 2′-O-me, has been reported to affect the viability of specific RNA viruses by modulating viral cap structures, viral replication, innate sensing pathways, and the innate immune response.¹ In addition, members of the coronaviruses and other virus species encode their own methyltransferases for self-methylating adenosine residues and promoting immune evasion. This makes the viral epitranscriptome an attractive target for therapeutic intervention.

What is SARS-CoV2?

Structure of the SARS-CoV-2 virion.
Taken from Kim et al., 2020.²

SARS-CoV-2 (also known as 2019-nCoV) consists of a positive-sense single-stranded RNA genome, spanning over 29,000 nucleotides in length, and 4 different types of structural proteins. The genome of positive-strand RNA viruses like coronaviruses can act as mRNA and be directly translated into protein within their host cells. Negative-strand RNA intermediates are also produced by coronaviruses that serve as templates for: positive-strand synthesis of genomic RNA, which is then packaged by the structural proteins to assemble virion offspring; and subgenomic RNA transcripts.

Several open reading frames (ORFs) have been distinguished within the “body” sequence of the SARS-CoV-2 genome, corresponding to viral structural elements (N, S, E, and M proteins) and accessory genes. The N, or nucleocapsid, protein encapsidates the genome, while the S (spike), E (envelope), and M (membrane) proteins constitute the surrounding lipid bilayer envelope. Of particular appeal is the S protein, which enables viral infection via host ACE-2 receptor recognition and membrane fusion. The 5′-most ORF, ORF 1a/1b (aka the replicase/transcriptase gene) is reported in coronaviruses to encode polymerases for viral RNA synthesis and other nonstructural proteins (nsps) (e.g., for poly(A) tailing). Whether or not these nsp translation products and their biological functions are conserved in the SARS-CoV-2 coronavirus species has yet to be fully determined.

How does RNA and m6A methylation play a role in the novel coronavirus?

Continued research in elucidating the dynamics of viral life cycle regulation by adenosine methylation will facilitate the design and development of novel antiviral therapies. N6-Methyladenosine, or m6A, is the most common and abundant eukaryotic RNA modification. It accounts for over 80% of all RNA methylation, affecting virtually every facet of ribonucleic acid biology: structure, splicing, localization, translation, stability, and turnover.³ Interestingly, m6A exhibits both pro- and anti-viral activities, depending on the virus species and host cell type.⁴

The RNA genome of SARS-CoV-2 contains more than 50 potential m6A sites based on the presence of specific sequence motifs for m6A modification by the RNA methylase complex METTL3/14, including GGACU(T), GGACA, and GGACC. Consequently, >0.64% of all adenosines, or 0.18% of all bases, in SARS-CoV-2 RNA could be m6A. Gain or loss of m6A can result in significant functional changes to RNA viruses, altering host cell fusion/entry, replication, transmission, pathogen intensity, and immune evasion. The m6A epitranscriptome of host cells, which plays a role in host resistance, can also undergo alterations after viral infection. Thus, studies of viral and host m6A modifications may reveal factors affecting SARS-CoV-2 infection and help identify novel targets for remedial treatment of COVID-19.

How to Study RNA Modifications in SARS-CoV-2 and Other viruses

For investigators interested in further exploring this intriguing modification, EpiGentek offers a variety of convenient and well-cited products, including quantification ELISAs, enzyme activity/inhibition assays, and highly specific antibodies, to aid your m6A research needs. In fact, to take the guesswork out of the process, we’ve compiled the steps into an end-to-end viral RNA modification workflow.

Once you decide on a type of study your lab is planning, refer to our workflow design to see which phases would go into the study design you are undertaking. Rest assured we have provided numerous informational resources as well as assay kit solutions for each phase in the workflow to make designing your impactful study simple so you can concentrate on expanding the world’s knowledge on this globally devastating virus.

References:

1. Gonzales-van Horn, S.R., & Sarnow, P. Making the Mark: The Role of Adenosine Modifications in the Life Cycle of RNA Viruses. Cell Host Microbe 21, 661-669 (2017).
2. Kim D, Lee JY, Yang JS, Kim JW, Kim VN, Chang H. The Architecture of SARS-CoV-2 Transcriptome. Cell. 2020;181(4):914-921.e10. doi:10.1016/j.cell.2020.04.011)
3. Zaccara, S., Ries, R.J., & Jaffrey, S.R. Reading, writing and erasing mRNA methylation. Nat Rev Mol Cell Biol 20, 608-624 (2019).
4. Dang, W., Xie, Y., Cao, P., Xin, S., Wang, J., Li, S., Li, Y., & Lu, J. N6-Methyladenosine and Viral Infection. Front Microbiol 10, 417 (2019).

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