Chemical crosslinking and LC/MS analysis to determine protein domain orientation: application to AbrB
To fully understand the modes of action of multi-protein complexes, it is essential to determine their overall global architecture and the specific relationships between domains and subunits. The transcription factor AbrB is a functional homotetramer consisting of two domains per monomer. Obtaining the high-resolution structure of tetrameric AbrB has been extremely challenging due to the independent character of these domains. To facilitate the structure determination process, we solved the NMR structures of both domains independently and utilized gas-phase cleavable chemical crosslinking and LC/MS(n) analysis to correctly position the domains within the full tetrameric AbrB protein structure.