Protein structural information derived from nmr chemical shift with the neural network program talos-n

Abstract

Chemical shifts are obtained at the first stage of any protein structural study by NMR spectroscopy. Chemical shifts are known to be impacted by a wide range of structural factors, and the artifcial neural network based TALOS-N program has been trained to extract backbone and side-chain torsion angles from1H,15N, and13C shifts. The program is quite robust and typically yields backbone torsion angles for more than 90% of the residues and side-chain χ1 rotamer information for about half of these, in addition to reliably predicting secondary structure. The use of TALOS-N is illustrated for the protein DinI, and torsion angles obtained by TALOS-N analysis from the measured chemical shifts of its backbone and13Cβ nuclei are compared to those seen in a prior, experimentally determined structure. The program is also particularly useful for generating torsion angle restraints, which then can be used during standard NMR protein structure calculations.