PNNL

Abstract

Homo-oligomer and multi-protein complex structure determination using solution NMR methods usually relies on inter-chain NOEs detected by X-filtered NOE experiments.1,2 These techniques, which require preparation of mixed isotopically labeled and unlabeled samples, are often not sensitive or difficult to interpret due to imperfect artifact suppression. Under the worst conditions, these methods can fail to provide unambiguous inter-chain NOEs, as was the case for Northeast Structural Genomics Consortium (NESG) target DhR8C, a homo-dimer of 62 residues. For Dh8rC, only a few unambiguous inter-chain 13C-edited/12C-filtered NOEs were detected, indicating potential problems including 1) tight dimer association resulting unfavorable chain exchange kinetics and a low population of mixed 13C/12C-labeled chains, 2) weak dimer association preventing measurement of inter-chain NOEs, or 3) a dimer interface whose nature prevented measurement or interpretation of inter-chain NOEs. This problem hindered the DhR8C homo-dimer structure determination using NMR methods alone.