PlyB is a bacteriophage endolysin that displays potent lytic activity toward Bacillus anthracis. PlyB has an N-terminal glycosyl hydrolase family 25 (GH25) catalytic domain and a C-terminal bacterial SH3-like domain, SH3b. Both domains are required for effective catalytic activity. Endolysins are produced by bacteriophages at the end of their life cycle and participate in lysing the bacterial cell in order to release the newly formed progeny. Endolysins (also referred to as endo-N-acetylmuramidases or peptidoglycan hydrolases) degrade bacterial cell walls by catalyzing the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues.

Endo-N-acetylmuramidases (muramidases) are lysozymes (also referred to as peptidoglycan hydrolases) that degrade bacterial cell walls by catalyzing the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues. This family of muramidases contains a glycosyl hydrolase family 25 (GH25) catalytic domain and is found in bacteria, fungi, slime molds, round worms, protozoans and bacteriophages. The bacteriophage members are referred to as endolysins which are involved in lysing the host cell at the end of the replication cycle to allow release of mature phage particles. Endolysins are typically modular enzymes consisting of a catalytically active domain that hydrolyzes the peptidoglycan cell wall and a cell wall-binding domain that anchors the protein to the cell wall. Endolysins generally have narrow substrate specificities with either intra-species or intra-genus bacteriolytic activity.

YegX is an uncharacterized bacterial protein with a glycosyl hydrolase family 25 (GH25) catalytic domain that is similar in sequence to the CH-type (Chalaropsis-type) lysozymes of the GH25 family of endolysins.

Domain of unknown function (DUF5776). Presumed stalk domain found in bacterial surface proteins forming tandem repeats with high sequence identity. This domain is also associated with other known bacterial surface protein stalks and adhesive domains.

Glycosyl hydrolases family 25.

Endolysinfrom Bacillus anthracis [Bacillus anthracis]

ChainA, PlyB [Bacteriophage sp.],2NW0_B Chain B, PlyB [Bacteriophage sp.]

High-resolutionstructure of catalytic domain of endolysin ply40 from bacteriophage P40 of Listeria monocytogenes [Listeria phage P40]

Crystalstructure of the CTP1L endolysin reveals how its activity is regulated by a secondary translation product [Clostridium phage phiCTP1]

X-raystructure of catalytic domain of endolysin from clostridium perfringens phage phiSM101 [Clostridium phage phiSM101]