New insights into complex formation by SARS-CoV-2 nsp10 and nsp14

• Published in: Nucleosides, nucleotides & nucleic acids pp. 1 - 15
• Main Authors: Sele, Céleste, Krupinska, Ewa, Andersson Rasmussen, Anna, Ekström, Simon, Hultgren, Lucas, Lou, Jiaqi, Kozielski, Frank, Fisher, S Zoë, Knecht, Wolfgang
• Format: Journal Article
• Language: English
• Published: United States 29.02.2024
• Subjects: Biologi; Biological Sciences; Natural Sciences; Naturvetenskap; Structural Biology; Strukturbiologi; protein–protein interactions; Covid-19; hydrogen-deuterium exchange mass spectrometry; microscale thermophoresis; coronavirus; exoribonuclease; multi-detection SEC
• ISSN: 1525-7770; 1532-2335
• DOI: 10.1080/15257770.2024.2321600

SARS-CoV-2 non-structural protein 10 (nsp10) is essential for the stimulation of enzymatic activities of nsp14 and nsp16, acting as both an activator and scaffolding protein. Nsp14 is a bifunctional enzyme with the N-terminus containing a 3'-5' exoribonuclease (ExoN) domain that allows the excision of nucleotide mismatches at the virus RNA 3'-end, and a C-terminal N7-methyltransferase (N7-MTase) domain. Nsp10 is required for stimulating both ExoN proofreading and the nsp16 2'-O-methyltransferase activities. This makes nsp10 a central player in both viral resistance to nucleoside-based drugs and the RNA cap methylation machinery that helps the virus evade innate immunity. We characterised the interactions between full-length nsp10 (139 residues), N- and C-termini truncated nsp10 (residues 10-133), and nsp10 with a C-terminal truncation (residues 1-133) with nsp14 using microscale thermophoresis, multi-detection SEC, and hydrogen-deuterium (H/D) exchange mass spectrometry. We describe the functional role of the C-terminal region of nsp10 for binding to nsp14 and show that full N- and C-termini of nsp10 are important for optimal binding. In addition, our H/D exchange experiments suggest an intermediary interaction of nsp10 with the N7-MTase domain of nsp14. In summary, our results suggest intermediary steps in the process of association or dissociation of the nsp10-nsp14 complex, involving contacts between the two proteins in regions not identifiable by X-ray crystallography alone.