Crystallization and Preliminary X-ray Diffraction Study of a Putative β-glycosidase from the Oral Bacteria Prevotella sp.

Glycoside hydrolases catalyze the hydrolysis of glycosidic bonds in diverse substrates. Oral bacteria can metabolize glycosidic precursors present in foods into aroma compounds. This metabolism has an impact on food sensory perception and presumably involves specific glycosidases belonging the glycoside hydrolases. Comprehensive elucidation of the structural and functional characteristics of glycoside hydrolases in oral bacteria is needed for advancing our understanding of aroma compound metabolism within the oral cavity. In this context, we have identified a glycoside hydrolase coded in the Prevotella sp. genome, exhibiting homology to β-glycosidases of the GH1 family. This enzyme, designated as PsBG1, was successfully expressed and purified for crystallographic investigation. PsBG1 crystals belong to the monoclinic space group P2₁ with unit cell parameters a = 134.2, b = 139.5, c = 172.7 Å and β = 99.8°. The crystal structure of PsBG1 was elucidated using molecular replacement techniques, utilizing a predictive model constructed with AlphaFold2. Analysis revealed that the asymmetric unit comprises three copies of homotetramer, while the predominant oligomeric state in solution is also a homotetramer. Ongoing efforts are focused on the refinement and detailed examination of the PsBG1 structure to clarify its functional significance in the metabolism of aromatic compounds.