Peptidoglycan recognition proteins (PGRPs) are pattern recognition receptors that bind, and in certain cases, hydrolyze peptidoglycans (PGNs) of bacterial cell walls. PGRPs have been divided into three classes: short PGRPs (PGRP-S), that are small (20 kDa) extracellular proteins; intermediate PGRPs (PGRP-I) that are 40-45 kDa and are predicted to be transmembrane proteins; and long PGRPs (PGRP-L), up to 90 kDa, which may be either intracellular or transmembrane. Several structures of PGRPs are known in insects and mammals, some bound with substrates like Muramyl Tripeptide (MTP) or Tracheal Cytotoxin (TCT). The substrate binding site is conserved in PGRP-LCx, PGRP-LE, and PGRP-Ialpha proteins. This family includes Zn-dependent N-Acetylmuramoyl-L-alanine Amidase, EC:3.5.1.28. This enzyme cleaves the amide bond between N-acetylmuramoyl and L-amino acids, preferentially D-lactyl-L-Ala, in bacterial cell walls. The structure for the bacteriophage T7 lysozyme shows that two of the conserved histidines and a cysteine are zinc binding residues. Site-directed mutagenesis of T7 lysozyme indicates that two conserved residues, a Tyr and a Lys, are important for amidase activity.

Mannosyl-glycoprotein endo-beta-N-acetylglucosaminidase. This family includes Mannosyl-glycoprotein endo-beta-N-acetylglucosaminidase EC:3.2.1.96. As well as the flageller protein J that has been shown to hydrolyze peptidoglycan.

N-acetylmuramoyl-L-alanine amidase. This family includes zinc amidases that have N-acetylmuramoyl-L-alanine amidase activity EC:3.5.1.28. This enzyme domain cleaves the amide bond between N-acetylmuramoyl and L-amino acids in bacterial cell walls (preferentially: D-lactyl-L-Ala). The structure is known for the bacteriophage T7 structure and shows that two of the conserved histidines are zinc binding.

Ami_2 domain.

Uncharacterized protein BB_0531 OS=Borreliella burgdorferi (strain ATCC 35210 / DSM 4680 / CIP 102532 / B31) OX=224326 GN=BB_0531 PE=3 SV=1