AUTOMATED COMBINED ASSIGNMENT OF NOESY SPECTRA AND 3-DIMENSIONAL PROTEIN-STRUCTURE DETERMINATION

A procedure for automated protein structure determination is presented that is based on an iterative procedure during which the NOESY peak l ist assignment and the structure calculation are performed simultaneou sly. The input consists of a list of NOESY peak positions and a list o f chemical shifts as obtained from sequence-specific resonance assignm ent. For the present applications of this approach the previously intr oduced NOAH routine was implemented in the distance geometry program D IANA. As an illustration, experimental 2D and 3D NOESY cross-peak list s of six proteins have been analyzed, for which complete sequence-spec ific H-1 assignments are available for the polypeptide backbone and th e amino acid side chains. The automated method assigned 70-90% of all NOESY cross peaks, which is on average 10% less than with the interact ive approach, and only between 0.8% and 2.4% of the automatically assi gned peaks had a different assignment than in the corresponding manual ly assigned peak lists. The structures obtained with NOAH/DIANA are in close agreement with those from manually assigned peak lists, and wit h both approaches the residual constraint violations correspond to hig h-quality NMR structure determinations. Systematic comparisons of the bundles of conformers that represent corresponding automatically and i nteractively determined structures document the absence of significant bias in either approach, indicating that an important step has been m ade towards automation of structure determination from NMR spectra.