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].

Fibronectin type 3 domain [General function prediction only].

Fibronectin type 3 domain [General function prediction only].

ChainA, Fn3-like protein [Acetivibrio thermocellus ATCC 27405],3MPC_B Chain B, Fn3-like protein [Acetivibrio thermocellus ATCC 27405]

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

N-acetylmuramoyl-L-alanine amidase CwlM OS=Bacillus licheniformis OX=1402 GN=cwlM PE=3 SV=1

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

Exoglucanase B OS=Cellulomonas fimi (strain ATCC 484 / DSM 20113 / JCM 1341 / NBRC 15513 / NCIMB 8980 / NCTC 7547) OX=590998 GN=cbhB PE=1 SV=1