THE SOLUTION STRUCTURE OF THE HISTIDINE-CONTAINING PROTEIN (HPR) FROMSTAPHYLOCOCCUS-AUREUS AS DETERMINED BY 2-DIMENSIONAL H-1-NMR SPECTROSCOPY

The three-dimensional solution structure of the heat-stable phosphocar rier protein HPr from Staphylococcus aureus was determined from two-di mensional NMR data by restrained molecular dynamics. It consists of a large twisted antiparallel beta-pleated sheet with four strands A, B, C, and D of amino acids 2-7, 34-37, 40-42 and 60-65. Three right-hande d helices A, B, C (amino acids 18-27, 47-53 and 71-85) are positioned on top of this sheet. The aromatic ring of His15 is located in a cleft formed by amino acids 12-17 and 55-58, only the nitrogen (Ndelta1) at om which can be phosphorylated by enzyme I is exposed to the water. Th e side chains of Thr12 and Arg17 are located close to the histidine ri ng. The regulatory serine residue (Ser46) is located in a hydrophobic patch, its hydroxyl group is water-accessible but forms hydrogen bonds with the amide groups of the backbone. The general features of the th ree-dimensional structure are similar to those found in HPr proteins f rom different microorganisms such as Escherichia coli, Bacillus subtil is and Strep-tococcus faecalis.