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Publication Abstract from PubMed

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 beta-glycosidic bond in 6'-P-beta-glucoside is cleaved, releasing 6-P-beta-glucose and the respective aglycon. This reaction is catalyzed by 6-P-beta-glucosidases, which belong to two glycoside hydrolase (GH) families: GH1 and GH4. Here, the high-resolution crystal structures of GH1 6-P-beta-glucosidases from Lactobacillus plantarum (LpPbg1) and Streptococcus mutans (SmBgl) and their complexes with ligands are reported. Both enzymes show hydrolytic activity towards 6'-P-beta-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-beta-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.

GH1-family 6-P-beta-glucosidases from human microbiome lactic acid bacteria.,Michalska K, Tan K, Li H, Hatzos-Skintges C, Bearden J, Babnigg G, Joachimiak A Acta Crystallogr D Biol Crystallogr. 2013 Mar;69(Pt 3):451-63. doi:, 10.1107/S0907444912049608. Epub 2013 Feb 16. PMID:23519420^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.