# Structural Characterization of the SARS-CoV-2 Replication and Transcription Complex

## TL;DR

This study explores the structure and function of the SARS-CoV-2 replication complex to understand how the virus efficiently replicates its large genome.

## Contribution

The study provides new structural insights into the SARS-CoV-2 replication and transcription complex using multiple biophysical techniques.

## Key findings

- The replication complex's stoichiometry and binding kinetics were analyzed using mass photometry and analytical ultracentrifugation.
- Structural and interaction data of the replication complex proteins with RNA were obtained using SAXS, SEC-SAXS, and SANS.
- The findings enhance understanding of how the SARS-CoV-2 replication complex is formed and functions.

## Abstract

At around 30 kb, the SARS-CoV-2 genome is one of the largest viral genomes among RNA viruses. As such, the replication machinery must be prepared to quickly and efficiently replicate this genome in order for the viral infection to effectively persist. In this study, we used several techniques to study the SARS-CoV-2 replication and transcription complex (RTC). We assessed complex stoichiometry and binding kinetics via mass photometry (MP) and analytical ultracentrifugation (AUC). We also employed small-angle x-ray scattering (SAXS), size-exclusion chromatography-coupled small-angle x-ray scattering (SEC-SAXS), and small-angle neutron scattering (SANS) in order to characterize the structure and protein-protein interactions of the SARS-CoV-2 replication complex proteins with each other and with RNA. This data has allowed us to gain further understanding of the formation and structure of the RTC.