Bionanoscience (BN) seminar by dr. David Dulin (Vrije Universiteit Amsterdam) on "Assembly and elongation dynamics of the SARS-CoV-2 replication-transcription complex: a single-molecule perspective".  The talk will start at 12:45h, and lunch is provided from 12:30h.

Abstract:
Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) has infected hundreds of millions and killed millions worldwide, largely due to the lack of effective therapeutics. To prepare against future deadly variants and coronavirus zoonosis, we must develop new and specific antiviral drugs.

SARS-CoV-2 expresses 16 non-structural proteins (nsp1-16) encoded in the ~30 kb long viral genome. Most nsp’s assemble into a replication-transcription complex (RTC). The RTC synthesizes all the viral RNAs in the host cell, and is therefore a key target for antiviral drugs. The RTC includes a core, made of the nsp12-polymerase and of the elongation factors nsp7 and nsp8.  To this core RTC associates several other nsp’s, such as the nsp13-helicase. Despite the wealth of structural studies reported in the last three years, the precise role of these viral proteins during the core RTC assembly and elongation, as well as the function of nsp13-helicase during RNA synthesis remain unclear. Furthermore, an elongation competent RTC in association with nsp13-helicase has not yet been reported. The lack of knowledge on the structure-function relationship of the different viral proteins forming the RTC impairs the rational design of novel antivirals.

Here, we applied high-throughput single-molecule magnetic tweezers to monitor the core RTC  dynamics from assembly to full primer extension in various compositions of the RTC, i.e. nsp7, nsp8, nsp12-polymerase and nsp13-helicase. From these high-spatiotemporal resolution data,  we derived new models describing the assembly of the core RTC, the nucleotide addition cycle of the core RTC, and how nsp13-helicase impacts the RTC elongation dynamics. Together, our results provide a new vision of the role of RTC viral proteins, establishing the foundation towards the assembly of a functional and complete CoV RTC.

Hot Topics in Bionanoscience
This seminar is combined with a Hot Topics session with the speaker, immediately after the seminar. These Hot Topics sessions allow for more in-depth discussions with the speaker. More information and registration can be found here.