Benchmarking predictive methods for small-angle X-ray scattering from atomic coordinates of proteins using maximum likelihood consensus data

Trewhella J, Vachette P, Larsen A, IUCrJ 11(5) (2024) DOI

SASDUB4 – Urate Oxidase Updated Consensus SAXS Data

Uricase
MWexperimental 137 kDa
MWexpected 136 kDa
log I(s) 1.03×100 1.03×10-1 1.03×10-2 1.03×10-3
Uricase small angle scattering data  s, nm-1
ln I(s)
Uricase Guinier plot ln 1.04×100 Rg: 3.2 nm 0 (3.2 nm)-2 s2
(sRg)2I(s)/I(0)
Uricase Kratky plot 1.104 0 3 sRg
p(r)
Uricase pair distance distribution function Rg: 3.2 nm 0 Dmax: 9.3 nm

Data validation


Fits and models


log I(s)
 s, nm-1
Uricase PDB (PROTEIN DATA BANK) model

log I(s)
 s, nm-1
Uricase PDB (PROTEIN DATA BANK) model

log I(s)
 s, nm-1
Uricase PDB (PROTEIN DATA BANK) model

log I(s)
 s, nm-1
Uricase PDB (PROTEIN DATA BANK) model

Updated consensus SAXS profiles generated using the ML-SAScombine tool (with log-s binning) for urate oxidase in 100 mM Tris pH 8.0, 150 mM NaCl. A total of 34 independent SAXS profiles (9 SEC-SAXS and 25 batch SAXS) contributed from 9 SAXS beamlines were combined. The minimum s value for SEC-SAXS data was 0.1 nm-1. Protein concentrations for batch measurements ranged from 0.1 - 7 mg/mL, and the minimum s value for these data (no less than 0.68 nm-1) was chosen to ensure exclusion of low-s data points affected by aggregation. The urate oxidase atomistic model for CRYSOL, Pepsi-SAXS, and FoXS calculations is the PDB ID 3L8W with small-molecule crystallisation agents removed, and a Modloop generated C-terminal sequence SLKSKL added to reflect the sequence for the protein as measured using SAXS. Custom WAXSiS simulations used the same coordinates with added explicit waters and ions to match the experimental conditions for the MD calculations. WAXSiS calculations include statistical errors and the error weighting for residual differences is therefore the square root of the sum of the squares of the experimental and WAXSiS statistical errors. Model fits are shown in order (top to bottom): CRYSOL (dummy waters hydration layer), FoXS, Pepsi-SAXS and custom WAXSiS. All three model fits with implicit hydration layer are to data on a log s-scale, while for custom WAXSiS the data are on a linear s-scale. The unusually good statistics for the consensus SAXS data generally give rise to large χ-square values for the model fits.

Additional data and information are made available in the full-entry zip archive and include: i) The input data for ML-SAScombine; ii) Runscripts used with ML-SAScombine; iii) Output files for updated consensus files from ML-SAScombine with log and linear s-binning; iv) Output files for combined SEC-SAS data from ML-SAScombine with log s-binning and; v) The original custom-WAXSiS model-fits with errors with the consensus data on the same s-grid.

Uricase
Mol. type   Protein
Organism   Aspergillus flavus
Olig. state   Tetramer
Mon. MW   34.1 kDa
 
UniProt   Q00511 (2-302)
Sequence   FASTA
 
PDB ID   3L8W
 
PDB ID   3L8W
 
PDB ID   3L8W