NP - RBD Biochemical data

RNA binding affinity - specificity

RBD - RNA interaction - binding affinities

(Kang Chen 2020 ActaPharmSinica PMID: 32363136

SPR with AAGUUCGUUU - WT) SARS-CoV-2 N-NTD is 140 µmol/L, around 2000-fold smaller than the value of Y110A mutant (KD = 330 mmol/L).

for structure see: NP - RBD-RNA structure - RNA binding mechanism

(Dinesh Boura PlosPath 2020 PMID: 33264373 finally accepted mauscript)

Kd of 8.3 ± 0.8 μM under physiological salt concentration. The binding is strongest in a low salt (50 mM NaCl) buffer (Kd < 1 μM) and very weak (Kd > 400 μM) in high salt buffer (500 mM) illustrating the electrostatic nature of RNA binding.

Mutants: R92E and R107E, showed essentially no binding to RNA (Kd > 400 μM)

The binding of wild type and all mutants of the SARS-CoV-2 N-NTD (residues 44–180) to RNA was measured using fluorescence anisotropy [33]. fluorescently labeled RNA (UCUCUAAACG labeled with 5’-hexachlorofluorescein). The concentration of RNA was 100 nM in the binding buffer (10 mM Tris pH 8.0, 150 mM NaCl, 3 mM β-mercaptoethanol) and the protein was titrated in the concentration range from 0 to 0.4 mM.

Binding affinities of the other N domains: RNA binding affinities - overview