Catalytic NodB homology domain of Streptococcus mutans polysaccharide deacetylase PgdA, Bacillus subtilis YheN, and similar proteins. This family is represented by a putative polysaccharide deacetylase PgdA from the oral pathogen Streptococcus mutans (SmPgdA) and Bacillus subtilis YheN (BsYheN), which are members of the carbohydrate esterase 4 (CE4) superfamily. SmPgdA is an extracellular metal-dependent polysaccharide deacetylase with a typical CE4 fold, with metal bound to a His-His-Asp triad. It possesses de-N-acetylase activity toward a hexamer of chitooligosaccharide N-acetylglucosamine, but not shorter chitooligosaccharides or a synthetic peptidoglycan tetrasaccharide. SmPgdA plays a role in tuning cell surface properties and in interactions with (salivary) agglutinin, an essential component of the innate immune system, most likely through deacetylation of an as-yet-unidentified polysaccharide. SmPgdA shows significant homology to the catalytic domains of peptidoglycan deacetylases from Streptococcus pneumoniae (SpPgdA) and Listeria monocytogenes (LmPgdA), both of which are involved in the bacterial defense mechanism against human mucosal lysozyme. The Bacillus subtilis genome contains six polysaccharide deacetylase gene homologs: pdaA, pdaB (previously known as ybaN), yheN, yjeA, yxkH and ylxY. The biological function of BsYheN is still unknown. This family also includes many uncharacterized polysaccharide deacetylases mainly found in bacteria.

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.

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

Catalytic NodB homology domain of Colletotrichum lindemuthianum chitin deacetylase and similar proteins. This family is represented by the chitin deacetylase (endo-chitin de-N-acetylase, ClCDA, EC 3.5.1.41) from Colletotrichum lindemuthianum (also known as Glomerella lindemuthiana), which is a member of the carbohydrate esterase 4 (CE4) superfamily. ClCDA catalyzes the hydrolysis of N-acetamido groups of N-acetyl-D-glucosamine residues in chitin, converting it to chitosan in fungal cell walls. It consists of a single catalytic domain similar to the deformed (alpha/beta)8 barrel fold adopted by other CE4 esterases, which encompasses a mononuclear metalloenzyme employing 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. It possesses a highly conserved substrate-binding groove, with subtle alterations that influence substrate specificity and subsite affinity. Unlike its bacterial homologs, ClCDA contains two intramolecular disulfide bonds that may add stability to this secreted protein. The family also includes many uncharacterized deacetylases and hypothetical proteins mainly from eukaryotes, which show high sequence similarity to ClCDA.

Polysaccharide deacetylase. This domain is found in polysaccharide deacetylase. This family of polysaccharide deacetylases includes NodB (nodulation protein B from Rhizobium) which is a chitooligosaccharide deacetylase. It also includes chitin deacetylase from yeast, and endoxylanases which hydrolyzes glucosidic bonds in xylan.

ChainA, Peptidoglycan N-acetylglucosamine deacetylase [[Eubacterium] rectale ATCC 33656]

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

Crystalstructure of the Xyl-CE4 domain of a multidomain xylanase from the hindgut metagenome of Trinervitermes trinervoides [uncultured bacterium]

T48deacetylase [Arthrobacter sp. AW19M34-1],5LGC_A T48 deacetylase with substrate [Arthrobacter sp. AW19M34-1]

Structureof a Streptococcus mutans CE4 esterase [Streptococcus mutans UA159]

Putative polysaccharide deacetylase YheN OS=Bacillus subtilis (strain 168) OX=224308 GN=yheN PE=3 SV=1

Bifunctional xylanase/deacetylase OS=Pseudobutyrivibrio xylanivorans OX=185007 GN=xyn11A PE=1 SV=2

Peptidoglycan-N-acetylglucosamine deacetylase PgdA OS=Listeria monocytogenes serovar 1/2a (strain ATCC BAA-679 / EGD-e) OX=169963 GN=pgdA PE=1 SV=1

Peptidoglycan-N-acetylglucosamine deacetylase PgdA OS=Listeria monocytogenes serotype 1/2a (strain EGD / Mackaness) OX=1334565 GN=pgdA PE=1 SV=1

Peptidoglycan-N-acetylglucosamine deacetylase PgdA OS=Listeria monocytogenes serotype 1/2a (strain 10403S) OX=393133 GN=pgdA PE=2 SV=1