학술논문
Enzymes in 3D: Synthesis, remodelling, and hydrolysis of cell wall (1,3;1,4)-β-glucans.
Document Type
Academic Journal
Author
Hrmova M; School of Agriculture, Food and Wine, and the Waite Research Institute, University of Adelaide, Glen Osmond, South Australia 5064, Australia.; Zimmer J; Howard Hughes Medical Institute and Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.; Bulone V; College of Medicine and Public Health, Flinders University, Bedford Park, South Australia 5042, Australia.; Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, Alba Nova University Centre, 106 91 Stockholm, Sweden.; Fincher GB; School of Agriculture, Food and Wine, and the Waite Research Institute, University of Adelaide, Glen Osmond, South Australia 5064, Australia.
Source
Publisher: American Society of Plant Biologists Country of Publication: United States NLM ID: 0401224 Publication Model: Print Cited Medium: Internet ISSN: 1532-2548 (Electronic) Linking ISSN: 00320889 NLM ISO Abbreviation: Plant Physiol Subsets: MEDLINE
Subject
Language
English
Abstract
Recent breakthroughs in structural biology have provided valuable new insights into enzymes involved in plant cell wall metabolism. More specifically, the molecular mechanism of synthesis of (1,3;1,4)-β-glucans, which are widespread in cell walls of commercially important cereals and grasses, has been the topic of debate and intense research activity for decades. However, an inability to purify these integral membrane enzymes or apply transgenic approaches without interpretative problems associated with pleiotropic effects has presented barriers to attempts to define their synthetic mechanisms. Following the demonstration that some members of the CslF sub-family of GT2 family enzymes mediate (1,3;1,4)-β-glucan synthesis, the expression of the corresponding genes in a heterologous system that is free of background complications has now been achieved. Biochemical analyses of the (1,3;1,4)-β-glucan synthesized in vitro, combined with 3-dimensional (3D) cryogenic-electron microscopy and AlphaFold protein structure predictions, have demonstrated how a single CslF6 enzyme, without exogenous primers, can incorporate both (1,3)- and (1,4)-β-linkages into the nascent polysaccharide chain. Similarly, 3D structures of xyloglucan endo-transglycosylases and (1,3;1,4)-β-glucan endo- and exohydrolases have allowed the mechanisms of (1,3;1,4)-β-glucan modification and degradation to be defined. X-ray crystallography and multi-scale modeling of a broad specificity GH3 β-glucan exohydrolase recently revealed a previously unknown and remarkable molecular mechanism with reactant trajectories through which a polysaccharide exohydrolase can act with a processive action pattern. The availability of high-quality protein 3D structural predictions should prove invaluable for defining structures, dynamics, and functions of other enzymes involved in plant cell wall metabolism in the immediate future.
Competing Interests: Conflict of interest statement. The authors could identify no conflicts of interest.
(© The Author(s) 2023. Published by Oxford University Press on behalf of American Society of Plant Biologists.)
Competing Interests: Conflict of interest statement. The authors could identify no conflicts of interest.
(© The Author(s) 2023. Published by Oxford University Press on behalf of American Society of Plant Biologists.)