Non-structural protein 7 (nsp7)
Function
Nsp7 and two different conformations of nsp8 work as a co-factor for nsp12. Together they form the minimal core polymerase complex, as without its co-factors, nsp12 has a low efficiency in polymerase activity. This complex mediates the RNA synthesis of the virus and is therefore an important part in the replication process [1]. It is suggested that the nsp7-nsp8 dimer might act as a primase in the complex[2].
Disease
The global COVID-19 pandemic, which started in 2019, is caused by the SARS-CoV-2.
Structure
The nsp7 is encoded on the open reading frame ORF1a and comprises 83 amino acids[2]. It forms a heterodimer with nsp8 to bind to nsp12 above the thumb domain of the RNA-dependent RNA polymerase (RdRp), mostly mediated by the nsp7. With this interaction, the conformation of the finger extension loops of the nsp12 are stabilized[1].
Nsp7 adopts a three helical bundle fold (α1: K2-L20, α2: S26-L41 and α3: T45-S61) [2]. α1 and α3 interact with the α1 and α2 helices of nsp8 to form the dimerization interface of 1,340 Ų, formed nearly entirely by hydrophobic interactions[2].
In the nsp7 of SARS-CoV-2 only one residue substitution is present when compared to SARS-CoV[1].
The to date published structures of complexes with nsp7 include 6BV2, 6WIQ, 6WQD, 7BW4, 6WTC, 6XEZ, 6M71, 7BV1, 7C2K, 7BZF, 6M5I, 6YHU, 6XIP, 6YYT, 7CTT, 6XQB, 6NUR, 7JLT, 2KYS, 7BTF, 5F22, 1YSY.
See also
Coronavirus_Disease 2019 (COVID-19)
SARS-CoV-2_virus_proteins
COVID-19 AlphaFold2 Models
