Abstact

Recent developments in NMR have extended the size range of proteins amenable to structural and functional characterization to include many larger proteins involved in important cellular processes. By applying a combination of residue-specific isotope labeling and protein deuteration strategies tailored to yield specific information, we were able to determine the solution structure and study structure-activity relationships of 3,4-dihydroxy-2-butanone-4-phosphate synthase, a 47-kDa enzyme from the Escherichia coli riboflavin biosynthesis pathway and an attractive target for novel antibiotics. Our investigations of the enzyme's ligand binding by NMR and site-directed mutagenesis yields a conclusive picture of the location and identity of residues directly involved in substrate binding and catalysis. Our studies illustrate the power of state-of-the-art NMR techniques for the structural characterization and investigation of ligand binding in protein complexes approaching the 50-kDa range in solution.