The contact interface of a 120 kD CheA-CheW complex by methyl TROSY interaction spectroscopy.

During bacterial chemotaxis, the histidine autokinase CheA interacts with the chemotaxis receptors with the help of the coupling protein CheW. This interaction is typical of many macromolecular complexes where protein-protein interactions play an important role. In this case, a relatively small protein, CheW, becomes part of a much larger complex. Here we describe a new method to map the residues at a protein-protein interface for macromolecular complexes of molecular weight greater than 100 kD.