ADAR activation by inducing a syn conformation at guanosine adjacent to an editing site

Journal Article · Sun Oct 16 00:00:00 EDT 2022 · Nucleic Acids Research

DOI:https://doi.org/10.1093/nar/gkac897· OSTI ID:1893169

Doherty, Erin E.; Karki, Agya; Wilcox, Xander E.; Mendoza, Herra G. ; Manjunath, Aashrita; Matos, Victorio Jauregui ; Fisher, Andrew J. ; Beal, Peter A.

Abstract ADARs (adenosine deaminases acting on RNA) can be directed to sites in the transcriptome by complementary guide strands allowing for the correction of disease-causing mutations at the RNA level. However, ADARs show bias against editing adenosines with a guanosine 5′ nearest neighbor (5′-GA sites), limiting the scope of this approach. Earlier studies suggested this effect arises from a clash in the RNA minor groove involving the 2-amino group of the guanosine adjacent to an editing site. Here we show that nucleosides capable of pairing with guanosine in a syn conformation enhance editing for 5′-GA sites. We describe the crystal structure of a fragment of human ADAR2 bound to RNA bearing a G:G pair adjacent to an editing site. The two guanosines form a Gsyn:Ganti pair solving the steric problem by flipping the 2-amino group of the guanosine adjacent to the editing site into the major groove. Also, duplexes with 2′-deoxyadenosine and 3-deaza-2′-deoxyadenosine displayed increased editing efficiency, suggesting the formation of a Gsyn:AH+anti pair. This was supported by X-ray crystallography of an ADAR complex with RNA bearing a G:3-deaza dA pair. This study shows how non-Watson–Crick pairing in duplex RNA can facilitate ADAR editing enabling the design of next generation guide strands for therapeutic RNA editing.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1893169
• Journal Information: Nucleic Acids Research, Journal Name: Nucleic Acids Research Vol. 50 Journal Issue: 19; ISSN 0305-1048
• Publisher: Oxford University Press
• Country of Publication: United Kingdom
• Language: English