Article Bacillus subtilis Crystallography, X-Ray Histidine Kinase Models, Molecular Phosphorylation Protein Conformation Protein Processing, Post-Translational Signal Transduction Transcription Factors X ray crystallography X ray diffraction amino acid sequence chemistry cloning computer model crystal structure crystallization entropy enzymology isothermal titration calorimetry metabolism molecular dynamics molecular model mutagenesis phosphatase phosphate transport phosphorylation phosphotransferase point mutation