Crystal Structure of 4,6-alpha-Glucanotransferase Supports Diet-Driven Evolution of GH70 Enzymes from alpha-Amylases in Oral Bacteria.Bai, Y., Gangoiti, J., Dijkstra, B.W., Dijkhuizen, L., Pijning, T.
(2017) Structure 25: 231-242
- PubMed: 28065507
- DOI: 10.1016/j.str.2016.11.023
- Primary Citation of Related Structures:
- PubMed Abstract:
- Lactobacillus reuteri Strains Convert Starch and Maltodextrins into Homoexopolysaccharides Using an Extracellular and Cell-Associated 4,6-alpha-Glucanotransferase
Bai, Y.,Boger, M.,van der Kaaij, R.M.,Woortman, A.J.J.,Pijning, T.,van Leeuwen, S.S.,Lammerts van Bueren, A.,Dijkhuizen, L.
(2016) Journal of Agricultural and Food Chemistry 64: 2941
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 lact ...
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.
Laboratory of Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands.