Rapid Data Collection for Protein Structure Determination by NMR Spectroscopy

A new approach is proposed to rapidly determine solution structures of small and medium-sized ¹³C,¹⁵N-labeled proteins, using a minimal number of experiments, such as 4D time-shared ¹³C/¹⁵N, ¹³C/¹⁵N-edited NOESY, 3D HNCA, and 3D MQ-(H)CCH-TOCSY. When the data are recorded on a 500 MHz spectrometer without using sparse sampling techniques, the experimental times were minimized to 2.5, 8.5, and 96 h for the HNCA, MQ-(H)CCH-TOCSY, and NOESY, respectively. The time-shared 4D NOESY contains four sub-spectra, one HC-NOESY-CH, one HC-NOESY-NH, one HN-NOESY-CH, and one HN-NOESY-NH. Sequence-specific assignment of backbone and side-chain resonances is achieved from the 3D spectra and the HC-NOESY-NH spectrum. Good initial structures can be quickly calculated using many unambiguous distance restraints that are easily obtained from the NOESY sub-spectra. The structures can be refined with more restraints assigned based on the initial structures. The approach has been demonstrated on ubiquitin (76 residues), liver fatty acid binding protein (129 residues, its NMR assignment and solution structure are presented here for the first time), and a cell−cell adhesion protein (214 residues). The approach will facilitate high throughput structure determination by NMR.