Bacterial alpha-L-rhamnosidase 6 hairpin glycosidase domain. This family consists of bacterial rhamnosidase A and B enzymes. L-Rhamnose is abundant in biomass as a common constituent of glycolipids and glycosides, such as plant pigments, pectic polysaccharides, gums or biosurfactants. Some rhamnosides are important bioactive compounds. For example, terpenyl glycosides, the glycosidic precursor of aromatic terpenoids, act as important flavouring substances in grapes. Other rhamnosides act as cytotoxic rhamnosylated terpenoids, as signal substances in plants or play a role in the antigenicity of pathogenic bacteria.
Two tandem repeats of the cystathionine beta-synthase (CBS pair) domains associated with the GGDEF (DiGuanylate-Cyclase (DGC)) domain. This cd contains two tandem repeats of the cystathionine beta-synthase (CBS pair) domains in association with the GGDEF (DiGuanylate-Cyclase (DGC)) domain. The GGDEF domain has been suggested to be homologous to the adenylyl cyclase catalytic domain and is thought to be involved in regulating cell surface adhesiveness in bacteria. The CBS domain, named after human CBS, is a small domain originally identified in cystathionine beta-synthase and is subsequently found in a wide range of different proteins. CBS domains usually occur in tandem repeats. They associate to form a so-called Bateman domain or a CBS pair based on crystallographic studies in bacteria. The CBS pair was used as a basis for this cd hierarchy since the human CBS proteins can adopt the typical core structure and form an intramolecular CBS pair. The interface between the two CBS domains forms a cleft that is a potential ligand binding site. The CBS pair coexists with a variety of other functional domains and this has been used to help in its classification here. It has been proposed that the CBS domain may play a regulatory role, although its exact function is unknown. Mutations of conserved residues within this domain are associated with a variety of human hereditary diseases, including congenital myotonia, idiopathic generalized epilepsy, hypercalciuric nephrolithiasis, and classic Bartter syndrome (CLC chloride channel family members), Wolff-Parkinson-White syndrome (gamma 2 subunit of AMP-activated protein kinase), retinitis pigmentosa (IMP dehydrogenase-1), and homocystinuria (cystathionine beta-synthase).
Crystalstructure of GH78 family rhamnosidase of Bacillus SP. GL1 AT 1.9 A [Bacillus sp. GL1],2OKX_B Crystal structure of GH78 family rhamnosidase of Bacillus SP. GL1 AT 1.9 A [Bacillus sp. GL1]