Figure 10-6: Signal arrest domains in endolysins of Gram-negative bacteria. The predicted N-terminal sequence of the endolysins of the lambdoid phages 21 (24), PS119 (Genbank accession CAA09710), P22 (32), and PS3 (Genbank accession CAA09701) and the non-lambdoid phages P1 (32), T4 (82), and HP1(8) are shown, with acidic and basic residues highlighted by shaded boxes. The predicted N-terminal signal arrest domain is boxed in some of the endolysin sequences. In each case, a glycine-proline rich domain, highlighted by italics and shading, separates the signal arrest domain from the rest of the protein sequence. The star indicates the conserved glutamate involved in catalysis in the T4 endolysin (88).