Elizabeth Campbell, PhD, Research Associate Professor, The Rockefeller University, "Structural basis for helicase-polymerase coupling in the SARS-CoV-2 replication-transcription complex-part I"

Dr. Campbell initiated by posing a question that can we apply some of the approaches towards understanding SARS-CoV-2 replication and transcription. A big unknown in the field of virology is the biological role of helicase in viral replication-personal common. The core questions were i) does the holo-RdRp interact with the helicase, nsp13; ii) how does nsp13 interact with the RdRp; iii) what is the role of nsp13 in replication and transcription; iv) would such structure/function info be useful for developing new antivirals. The research found that the RdRp has to deal with unraveling the secondary structure and/or DS RNA in the genome. Evidence that nsp13 helicase binds the RTC via nsp8. All components are active. Gel shifts and native mass spectrometry confirm a complex. NiRan domain is ubiquitous but divergent in nidoviruses. NiRan domain is nucleotidylated by GTP and UTP in the arterivirus EAV. NiRan is structurally similar to pseudokinase with AMPylation activity. Structural architecture of the SARS CoV-2 transcription/replication complex (RTC) with nsp13 helicase. The remaining questions were i) what are the biological implications of the structure; ii) what else is part of the RTC complex; iii) what is the sequence of assembly; and iv) how are these functions coordinated.