title: GH1-family 6-P-β-glucosidases from human microbiome lactic acid bacteria.
abstract: In lactic acid bacteria and other bacteria, carbohydrate uptake is mostly governed by phosphoenolpyruvate-dependent phosphotransferase systems (PTSs). PTS-dependent translocation through the cell membrane is coupled with phosphorylation of the incoming sugar. After translocation through the bacterial membrane, the β-glycosidic bond in 6'-P-β-glucoside is cleaved, releasing 6-P-β-glucose and the respective aglycon. This reaction is catalyzed by 6-P-β-glucosidases, which belong to two glycoside hydrolase (GH) families: GH1 and GH4. Here, the high-resolution crystal structures of GH1 6-P-β-glucosidases from Lactobacillus plantarum (LpPbg1) and Streptococcus mutans (SmBgl) and their complexes with ligands are reported. Both enzymes show hydrolytic activity towards 6'-P-β-glucosides. The LpPbg1 structure has been determined in an apo form as well as in a complex with phosphate and a glucose molecule corresponding to the aglycon molecule. The S. mutans homolog contains a sulfate ion in the phosphate-dedicated subcavity. SmBgl was also crystallized in the presence of the reaction product 6-P-β-glucose. For a mutated variant of the S. mutans enzyme (E375Q), the structure of a 6'-P-salicin complex has also been determined. The presence of natural ligands enabled the definition of the structural elements that are responsible for substrate recognition during catalysis.
authors.affiliation: Midwest Center for Structural Genomics, Biosciences Division, Argonne National Laboratory, Argonne, Illinois, USA.
authors.forename: Karolina
authors.initials: K
authors.lastname: Michalska
authors.forename: Kemin
authors.initials: K
authors.lastname: Tan
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Catherine
authors.initials: C
authors.lastname: Hatzos-Skintges
authors.forename: Jessica
authors.initials: J
authors.lastname: Bearden
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Babnigg
authors.forename: Andrzej
authors.initials: A
authors.lastname: Joachimiak
mesh_terms: D018360:Crystallography, X-Ray; D005959:Glucosidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D048191:Lactiplantibacillus plantarum / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D008024:Ligands; D054892:Metagenome; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry*; D013295:Streptococcus mutans / Q000201:enzymology* / Q000235:genetics
chemical_list: D008024:Ligands; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D005959:Glucosidases; C066586:6-phospho-beta-glucosidase
keywords: 6-P-β-glucosidases; GH1; cellobiose; gentiobiose; glycoside hydrolases; salicin