Protein heteronuclear NMR assignments using mean-field simulated annealing

A computational method for the assignment of the NMR spectra of larger (21 kDa) proteins using a set of six of the most sensitive heteronuclear multidimensional nuclear magnetic resonance experiments is described. Connectivity data obtained from HNC alpha, HN(CO)C alpha, HN(C alpha)H alpha, and H alpha (C alpha CO)NH and spin-system identification data obtained from CP-(H)CCH-TOCSY and CP-(H)C(C alpha CO)NH-TOCSY were used to perform sequence-specific assignments using a mean-field formalism and simulated annealing. This mean-field method reports the resonance assignments in a probabilistic fashion, displaying the certainty of assignments in an unambiguous and quantitative manner. This technique was applied to the NMR data of the 172-residue peptide-binding domain of the E. coli heat-shock protein, DnaK. The method is demonstrated to be robust to significant amounts of missing, spurious, noisy, extraneous, and erroneous data.