title: Crystal Structure of 4,6-α-Glucanotransferase Supports Diet-Driven Evolution of GH70 Enzymes from α-Amylases in Oral Bacteria.
abstract: Food processing and refining has dramatically changed the human diet, but little is known about whether this affected the evolution of enzymes in human microbiota. We present evidence that glycoside hydrolase family 70 (GH70) glucansucrases from lactobacilli, synthesizing α-glucan-type extracellular polysaccharides from sucrose, likely evolved from GH13 starch-acting α-amylases, via GH70 4,6-α-glucanotransferases. The crystal structure of a 4,6-α-glucanotransferase explains the mode of action and unique product specificity of these enzymes. While the α-amylase substrate-binding scaffold is retained, active-site loops adapted to favor transglycosylation over hydrolysis; the structure also gives clues as to how 4,6-α-glucanotransferases may have evolved further toward sucrose utilization instead of starch. Further supported by genomic, phylogenetic, and in vivo studies, we propose that dietary changes involving starch (and starch derivatives) and sucrose intake were critical factors during the evolution of 4,6-α-GTs and glucansucrases from α-amylases, allowing oral bacteria to produce extracellular polymers that contribute to biofilm formation from different substrates.
authors.affiliation: Laboratory of Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands.
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Laboratory of Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands.
authors.forename: Joana
authors.initials: J
authors.lastname: Gangoiti
authors.affiliation: Laboratory of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands.
authors.forename: Bauke W
authors.initials: BW
authors.lastname: Dijkstra
authors.affiliation: Laboratory of Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands.
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
authors.affiliation: Laboratory of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands. Electronic address: t.pijning@rug.nl.
authors.forename: Tjaard
authors.initials: T
authors.lastname: Pijning
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002240:Carbohydrate Sequence; D020134:Catalytic Domain; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D019143:Evolution, Molecular; D000069196:Gastrointestinal Microbiome / Q000235:genetics; D015870:Gene Expression; D006004:Glycogen Debranching Enzyme System / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D052200:Limosilactobacillus reuteri / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D008958:Models, Molecular; D009154:Mutation; D010802:Phylogeny; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013213:Starch / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity; D013395:Sucrose / Q000737:chemistry* / Q000378:metabolism; D000516:alpha-Amylases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004040:Dietary Carbohydrates; D006004:Glycogen Debranching Enzyme System; D011994:Recombinant Proteins; D013395:Sucrose; D013213:Starch; C020569:4 alpha-glucanotransferase; D000516:alpha-Amylases
keywords: 4,6-α-Glucanotransferase; Lactobacillus reuteri; crystal structure; dental caries; lactic acid bacteria; starch