Figure 1

Crystal structure of the N-terminal cysteine-histidine dependent amido-hydrolase/peptidase domain (CHAP _K ) of the endolysin LysK from staphylococcal bacteriophage K. (A) Overall structure. Beta-strands are shown in green, alpha-helices in blue and 3₁₀-helices in red. The calcium ion is shown in grey, the zinc ion in white. The N-terminal end (Nt), residue 165, the alpha-helices and the beta-strands are labelled. (B). Topology diagram. The same labelling is used as in panel A. (C). Superposition of CHAP_K (magenta) onto structure onto the CHAP domain of the streptococcal phage endolysin PlyC (PDB entry 4 F88; cyan). (D). Space-filling representation with conserved residues in almost the same orientation as panel A, but slightly tilted forward to better illustrate the hydrophobic groove, which is indicated with an arrow. The colour coding goes from blue for less conserved residues, via white, to purple for the most conserved residues.