N-acetylmuramoyl-L-alanine amidase or MurNAc-LAA (also known as peptidoglycan aminohydrolase, NAMLA amidase, NAMLAA, Amidase 3, and peptidoglycan amidase; EC 3.5.1.28) is an autolysin that hydrolyzes the amide bond between N-acetylmuramoyl and L-amino acids in certain cell wall glycopeptides. These proteins are Zn-dependent peptidases with highly conserved residues involved in cation co-ordination. MurNAc-LAA in this family is one of several peptidoglycan hydrolases (PGHs) found in bacterial and bacteriophage or prophage genomes that are involved in the degradation of the peptidoglycan. In Escherichia coli, there are five MurNAc-LAAs present: AmiA, AmiB, AmiC and AmiD that are periplasmic, and AmpD that is cytoplasmic. Three of these (AmiA, AmiB and AmiC) belong to this family, the other two (AmiD and AmpD) do not. E. coli AmiA, AmiB and AmiC play an important role in cleaving the septum to release daughter cells after cell division. In general, bacterial MurNAc-LAAs are members of the bacterial autolytic system and carry a signal peptide in their N-termini that allows their transport across the cytoplasmic membrane. However, the bacteriophage MurNAc-LAAs are endolysins since these phage-encoded enzymes break down bacterial peptidoglycan at the terminal stage of the phage reproduction cycle. As opposed to autolysins, almost all endolysins have no signal peptides and their translocation through the cytoplasmic membrane is thought to proceed with the help of phage-encoded holin proteins. The amidase catalytic module is fused to another functional module (cell wall binding module or CWBM) either at the N- or C-terminus, which is responsible for high affinity binding of the protein to the cell wall.

N-acetylmuramoyl-L-alanine amidase. This enzyme domain cleaves the amide bond between N-acetylmuramoyl and L-amino acids in bacterial cell walls.

N-acetylmuramoyl-L-alanine amidase [Cell wall/membrane/envelope biogenesis].

triple tyrosine motif-containing protein; Provisional

Ami_3 domain.

ChainB, Germination-specific N-acetylmuramoyl-L-alanine amidase, Autolysin [Clostridioides difficile]

Structureof the catalytic domain of CwlV, N-acetylmuramoyl-L-alanine amidase from Bacillus(Paenibacillus) polymyxa var.colistinus [Paenibacillus polymyxa]

ChainA, Cell wall hydrolase/autolysin [Nostoc punctiforme PCC 73102]

ChainA, N-acetylmuramoyl-L-alanine amidase [Clostridioides difficile 630]

Crystalstructure of the E. coli N-acetylmuramoyl-L-alanine amidase AmiC [Escherichia coli K-12]

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

Uncharacterized protein YqiI OS=Bacillus subtilis (strain 168) OX=224308 GN=yqiI PE=3 SV=3

Germination-specific N-acetylmuramoyl-L-alanine amidase OS=Bacillus subtilis (strain 168) OX=224308 GN=cwlD PE=1 SV=1

N-acetylmuramoyl-L-alanine amidase LytC OS=Bacillus subtilis (strain 168) OX=224308 GN=lytC PE=1 SV=1

Endolysin OS=Bacillus phage SPP1 OX=10724 GN=25 PE=4 SV=1