SARS-CoV-2 3’-5’ Exonuclease Antibody #99098

The cause of the COVID-19 pandemic is a novel and highly pathogenic coronavirus, termed SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2). SARS-CoV-2 is a member of the Coronaviridae family of viruses (1). The genome of SARS-CoV-2 is relatively large and encodes up to 29 open reading frames (ORFs). These include ORF1a and ORF1b (further processed into 16 non-structural proteins), 9 accessory proteins, and 4 canonical structural proteins: spike (S), envelope (E), membrane (M), and nucleocapsid (N) (2).

SARS-CoV-2 3’-5’ exonuclease, or ExoN, is a non-structural protein (Nsp14) translated from ORF1b (2). It is a proofreading enzyme that functions in the replicase holoenzyme to read, excise, and repair errors in the newly transcribed viral RNA (3). RNA viruses generally have a high mutation rate and Coronaviridae, and others among the Nidovirales genus, have the largest and most complex genomes of RNA viruses (4). The 3’-5’ exonuclease is highly conserved between Coronaviruses, suggesting it’s important to the maintenance of such a large genome (5). The 3’-5’ exonuclease also provides a functionality to the RNA capping process, alongside the 2’-ribose methyl transferase (Nsp14), the helicase (Nsp13), and a guanylyl transferase (6,7). It is, however, the exonuclease function that is the key challenge to antiviral drug design with nucleoside analogue approaches (8).