delta-lactam-biosynthetic de-N-acetylase. Muramic delta-lactam is an unusual constituent of peptidoglycan, found only in bacterial spores in the peptidoglycan wall, or spore cortex. The proteins in this family are PdaA (yfjS), a member of a larger family of polysaccharide deacetylases, and are specificially involved in delta-lactam biosynthesis. PdaA acts immediately after CwlD, an N-acetylmuramoyl-L-alanine amidase and performs a de-N-acetylation. PdaA may also perform the following transpeptidation for lactam ring formation, as heterologous expression in E. coli of CwlD and PdaA together is sufficient for delta-lactam production. [Cell envelope, Biosynthesis and degradation of murein sacculus and peptidoglycan, Cellular processes, Sporulation and germination]

Catalytic NodB homology domain of Bacillus subtilis polysaccharide deacetylase PdaA, and its bacterial homologs. The Bacillus subtilis genome contains six polysaccharide deacetylase gene homologs: pdaA, pdaB (previously known as ybaN), yheN, yjeA, yxkH and ylxY. This family is represented by Bacillus subtilis pdaA gene encoding polysaccharide deacetylase BsPdaA, which is a member of the carbohydrate esterase 4 (CE4) superfamily. BsPdaA deacetylates peptidoglycan N-acetylmuramic acid (MurNAc) residues to facilitate the formation of muramic delta-lactam, which is required for recognition of germination lytic enzymes. BsPdaA deficiency leads to the absence of muramic delta-lactam residues in the spore cortex. Like other CE4 esterases, BsPdaA consists of a single catalytic NodB homology domain that appears to adopt a deformed (beta/alpha)8 barrel fold with a putative substrate binding groove harboring the majority of the conserved residues. It utilizes a general acid/base catalytic mechanism involving a tetrahedral transition intermediate, where a water molecule functions as the nucleophile tightly associated to the zinc cofactor.

Catalytic NodB homology domain of rhizobial NodB-like proteins. This family belongs to the large and functionally diverse carbohydrate esterase 4 (CE4) superfamily, whose members show strong sequence similarity with some variability due to their distinct carbohydrate substrates. It includes many rhizobial NodB chitooligosaccharide N-deacetylase (EC 3.5.1.-)-like proteins, mainly from bacteria and eukaryotes, such as chitin deacetylases (EC 3.5.1.41), bacterial peptidoglycan N-acetylglucosamine deacetylases (EC 3.5.1.-), and acetylxylan esterases (EC 3.1.1.72), which catalyze the N- or O-deacetylation of substrates such as acetylated chitin, peptidoglycan, and acetylated xylan. All members of this family contain a catalytic NodB homology domain with the same overall topology and a deformed (beta/alpha)8 barrel fold with 6- or 7 strands. Their catalytic activity is dependent on the presence of a divalent cation, preferably cobalt or zinc, and they employ a conserved His-His-Asp zinc-binding triad closely associated with the conserved catalytic base (aspartic acid) and acid (histidine) to carry out acid/base catalysis. Several family members show diversity both in metal ion specificities and in the residues that coordinate the metal.

Catalytic NodB homology domain of Clostridium thermocellum acetylxylan esterase and its bacterial homologs. This family is represented by Clostridium thermocellum acetylxylan esterase (CtAXE, EC 3.1.1.72), a member of the carbohydrate esterase 4 (CE4) superfamily. CtAXE deacetylates O-acetylated xylan, a key component of plant cell walls. It shows no detectable activity on generic esterase substrates including para-nitrophenyl acetate. It is specific for sugar-based substrates and will precipitate acetylxylan, as a consequence of deacetylation. CtAXE is a monomeric protein containing a catalytic NodB homology domain with the same overall topology and a deformed (beta/alpha)8 barrel fold as other CE4 esterases. However, due to differences in the topography of the substrate-binding groove, the chemistry of the active center, and metal ion coordination, CtAXE has different metal ion preference and lacks activity on N-acetyl substrates. It is significantly activated by Co2+. Moreover, CtAXE displays distinctly different ligand coordination to the metal ion, utilizing an aspartate, a histidine, and four water molecules, as opposed to the conserved His-His-Asp zinc-binding triad of other CE4 esterases.

Peptidoglycan/xylan/chitin deacetylase, PgdA/CDA1 family [Carbohydrate transport and metabolism, Cell wall/membrane/envelope biogenesis].

Structureof Bacillus subtilis PdaA in complex with NAG, a family 4 Carbohydrate esterase. [Bacillus subtilis],1W1A_2 Structure of Bacillus subtilis PdaA in complex with NAG, a family 4 Carbohydrate esterase. [Bacillus subtilis],1W1B_1 Structure of Bacillus subtilis PdaA with Cadmium, a family 4 Carbohydrate esterase. [Bacillus subtilis],1W1B_2 Structure of Bacillus subtilis PdaA with Cadmium, a family 4 Carbohydrate esterase. [Bacillus subtilis]

Structureof Bacillus subtilis PdaA, a family 4 Carbohydrate esterase. [Bacillus subtilis],1W17_B Structure of Bacillus subtilis PdaA, a family 4 Carbohydrate esterase. [Bacillus subtilis]

CrystalStructure Of B. Subtilis Polysaccharide Deacetylase Northeast Structural Genomics Consortium Target Sr127. [Bacillus subtilis],1NY1_B Crystal Structure Of B. Subtilis Polysaccharide Deacetylase Northeast Structural Genomics Consortium Target Sr127. [Bacillus subtilis]

Structureof a family 4 carbohydrate esterase from Bacillus anthracis [Bacillus anthracis str. Ames]

ChainA, Predicted xylanase/chitin deacetylase [Caldanaerobacter subterraneus subsp. tengcongensis MB4]

Uncharacterized 30.6 kDa protein in fumA 3'region OS=Geobacillus stearothermophilus OX=1422 PE=3 SV=1

Peptidoglycan-N-acetylmuramic acid deacetylase PdaA OS=Bacillus subtilis (strain 168) OX=224308 GN=pdaA PE=1 SV=1

Chitooligosaccharide deacetylase OS=Bradyrhizobium sp. (strain ANU 289) OX=186901 GN=nodB PE=3 SV=2

Chitooligosaccharide deacetylase OS=Rhizobium meliloti (strain 1021) OX=266834 GN=nodB PE=3 SV=3

Chitooligosaccharide deacetylase OS=Bradyrhizobium elkanii OX=29448 GN=nodB PE=3 SV=1