H-1-NMR AND N-15-NMR ASSIGNMENT AND SOLUTION STRUCTURE OF THE CHEMOTACTIC ESCHERICHIA-COLI CHE Y-PROTEIN

Che Y is a 129-residue parallel alpha/beta protein involved in bacterial chemotaxis. We have used this protein as a model to study the folding reaction of parallel alpha/beta proteins. As a first step we carried out the complete assignment of the H-1 and N-15 spectra from Escherichia coli Che Y protein on the basis of two-dimensional H-1 homonuclear and H-1-N-15 heteronuclear experiments by using sequence-specific methods. Our assignments differ from the preliminary assignments made by Kar et al. [Kar, L., Matsumura, P. & Johnson, M. E. (1992) Biochem. J. 287, 521-531] of aromatic residues obtained by comparison of NOEs with short proton-proton distances in the crystal structure of Che Y. The analysis of the extension of the secondary elements, as well as a preliminary calculation of the three-dimensional structure, indicate that the solution structure is closely coincident with the single crystal structure determined by X-ray diffraction.