Targets for drug development
Sequence and structure of the new coronavirus SARS-CoV-2 have been well studied and described. Of particular interest with respect to diagnostics and drug development are the spike protein (S-protein), due to its role in the interaction with human host receptors, and the highly conserved nucleocapsid protein (N-protein) with high immunogenicity. Beside, the main protease Mpro proves as an interessting target, as a key enzyme of SARS-CoV-2 without close human homologues.
At BIOZOL you can obtain recombinant S-proteins in different variants, N-Proteins, and the main protease (Mpro) from different expression systems, as well as suitable substrates, antibodies and assays.
The spike protein on the surface of the virus envelope is the most important target for neutralizing antibodies and vaccines. It consists of two subunits, S1 and S2.
S1 contains the receptor binding domain (RBD), which is responsible for recognition and binding of the cell surface receptor (in human respiratory epithelial cells ACE2).
The S2 subunit is required for membrane fusion.
Figure: PDB 6VXX, Structure of the SARS-CoV-2 spike glycoprotein (closed state), Mol*
full length SARS-CoV-2 Spike Protein
Our partner Bioserv UK is the first company to offer a fully expressed SARS-CoV-2 spike protein (aa 1 - 1273, including the signal peptide). The protein contains a RRAR→GSAG mutated furin interface and a C-terminal Rho1D4 tag for affinity purification. Bioserv UK's full length SARS-CoV-2 spike protein (Item No. BIS-BSV-COV-PR-*) is produced in HEK293 mammalian cells to obtain the most authentic post-translational modifications possible.
SARS-CoV-2 Spike Protein, D614G variant
In the early course of the COVID-19 pandemic, a more infectious variant of SARS-CoV-2, an D→G mutation at position 614, became established in Europe and is now spreading worldwide. (Isabel et al., Zhang et al.) The SARS-CoV-2 spike protein from our partner Daresbury Protein in the D614G variant (Item No. DBP-DPREC-019) comprises amino acids 16-1213, contains a mutated furin interface and two stabilizing mutations (K986P and V987P), as described by Amanat et al.
Other recombinant SARS-CoV-2 S-Proteins:
>> S-Protein and subunits (S1, S2, S1 RBD) from Sino Biological
>> HEK293 expressed S1 and S2 glycoproteins from The Native Antigen Company
>> Spike-Protein S1 RBD from Signalchem, expressed in CHO cells
The nucleocapsid protein is the most detectable protein in coronaviruses. It is a highly immunogenic phosphoprotein and normally highly conserved. The N protein is therefore often used as a marker in diagnostic assays.
Selected recombinant SARS-CoV-2 N-Proteins:
The main protease (Mpro) is a key enzyme of SARS-CoV-2 and is required for viral replication and transcription. Mpro activates the viral replicase by degrading replicase polyproteins at eleven conserved cleavage sites.
Figure: SARS-CoV-2 main protease (Mpro) in complex with inhibitor N3 (PDB 6LU7), Jin et al.
Since no closely related homologues of SARS-CoV-2 Mpro occur in humans, the protease is an attractive target for potential therapeutics.
Our partner company Carbosynth offers an assay toolkit for the development of such therapeutics, including the recombinant protease (Item No. CBS-BS178678), the fluorogenic Mpro substrate Ac-Abu-Tle-Leu-Gln-AMC (Item No. CBS-FA178674), the required buffer components and a portfolio of relevant inhibitors.