Putative catalytic NodB homology domain of a hypothetical protein Ecf1 from Escherichia coli and similar proteins. This family contains a hypothetical protein Ecf1 from Escherichia coli and its prokaryotic homologs. Although their biochemical properties remain to be determined, members in this family contain a conserved domain with a 5-stranded beta/alpha barrel, which is similar to the catalytic NodB homology domain of rhizobial NodB-like proteins, belonging to the larger carbohydrate esterase 4 (CE4) superfamily.

Putative catalytic NodB homology domain of uncharacterized bacterial polysaccharide deacetylases which consist of a 5-stranded beta/alpha barrel. This family contains many uncharacterized bacterial polysaccharide deacetylases. Although their biological functions remain unknown, all members of the family are predicted to contain a conserved domain with a 5-stranded beta/alpha barrel, which is similar to the catalytic NodB homology domain of rhizobial NodB-like proteins, belonging to the larger carbohydrate esterase 4 (CE4) superfamily.

Putative catalytic NodB homology domain of gellan lyase and similar proteins. This family is represented by the extracellular polysaccharide-degrading enzyme, gellan lyase (gellanase, EC 4.2.2.-), from Bacillus sp. The enzyme acts on gellan exolytically and releases a tetrasaccharide of glucuronyl-glucosyl-rhamnosyl-glucose with unsaturated glucuronic acid at the nonreducing terminus. The family also includes many uncharacterized prokaryotic polysaccharide deacetylases, which show high sequence similarity to Bacillus sp. gellan lyase. Although their biological functions remain unknown, all members of the family contain a conserved domain with a 6-stranded beta/alpha barrel, which is similar to the catalytic NodB homology domain of rhizobial NodB-like proteins, belonging to the larger carbohydrate esterase 4 (CE4) superfamily.

Putative catalytic NodB homology domain of Mesorhizobium loti Mlr8448 protein and its bacterial homologs. This family contains Mesorhizobium loti Mlr8448 protein and its bacterial homologs. Although their biochemical properties are yet to be determined, members in this subfamily contain a conserved domain with a 5-stranded beta/alpha barrel, which is similar to the catalytic NodB homology domain of rhizobial NodB-like proteins, belonging to the larger carbohydrate esterase 4 (CE4) superfamily.

Putative catalytic NodB homology domain of PgaB, IcaB, and similar proteins which consist of a deformed (beta/alpha)8 barrel fold with 5- or 6-strands. 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 bacterial poly-beta-1,6-N-acetyl-D-glucosamine N-deacetylase PgaB, hemin storage system HmsF protein in gram-negative species, intercellular adhesion proteins IcaB, and many uncharacterized prokaryotic polysaccharide deacetylases. It also includes a putative polysaccharide deacetylase YxkH encoded by the Bacillus subtilis yxkH gene, which is one of six polysaccharide deacetylase gene homologs present in the Bacillus subtilis genome. Sequence comparison shows all family members contain a conserved domain similar to the catalytic NodB homology domain of rhizobial NodB-like proteins, which consists of a deformed (beta/alpha)8 barrel fold with 6 or 7 strands. However, in this family, most proteins have 5 strands and some have 6 strands. Moreover, long insertions are found in many family members, whose function remains unknown.