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SAXS
data from solutions of
Non Structural Protein 15 in complex with RNA 9mer
in
20mM HEPES, 150mM Nacl, pH 7.5
were collected
on the
Anton Paar SAXSpace instrument (CSIR-Central Drug Research Institute, Lucknow, India)
using a Mythen2 R 1K detector
at a sample-detector distance of 0.3 m and
at a wavelength of λ = 1.54 nm
(I(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle).
One solute concentration of 4.00 mg/ml was measured
at 10°C.
Three successive
900 second frames were collected.
The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.
Small-angle X-ray scattering (SAXS) measurements were performed to characterize the solution structure of the SARS-CoV-2 Non-Structural Protein 15 (NSP15) in complex with a 9-mer RNA oligonucleotide (AAACGACAU) under catalytically relevant conditions. NSP15 is a uridine-specific endoribonuclease that functions as a hexamer. The SAXS sample was prepared in the presence of Mn²⁺ ions, which are essential for its enzymatic activity and RNA binding.
The complex was modeled as a single scattering particle composed of six NSP15 monomers, each associated with a 9-mer RNA, and validated through molecular weight estimation from both I(0) and Porod analysis. The SAXS profile supports a monodisperse and compact hexameric assembly of NSP15 in solution. The data correlate well with the known crystallographic structure (e.g., PDB: 7N33), indicating the preservation of the oligomeric state and RNA interactions in solution under physiological ionic and metal conditions.
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s, nm-1
