SIGNALING PROTEIN, RESPONSE REGULATOR, RECEIVER DOMAIN, BEF3, TWO-COMPONENT SIGNAL TRANSDUCTION, CHEMOTAXIS, CYTOPLASM, FLAGELLAR ROTATION, MAGNESIUM, METAL-BINDING, PHOSPHOPROTEIN, TWO- COMPONENT REGULATORY SYSTEM 3FFW CRYSTAL STRUCTURE OF CHEY TRIPLE MUTANT F14Q, N59K, E89Y COMPLEXED WITH BEF3- AND MN2+