Utilization of dietary mixed-linkage β-glucans by the Firmicute Blautia producta

Singh, Ravindra; Niharika, Jayashree; Thakur, Raksha; Wagstaff, Ben A.; Kumar, Gulshan; Kurata, Rikuya; Patel, Dhaval; Levy, Colin; Miyazaki, Takatsugu; Field, Robert A.

doi:10.1016/j.jbc.2023.104806

Cited by 2 publications

(1 citation statement)

References 96 publications

(143 reference statements)

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“…The beneficial effects of these polysaccharides may, in part at least, be attributable to alterations in the bacterial microbiome of the large intestine induced by (1,3;1,4)-β-glucans in the diet ( Gorham et al 2017 ). Human gut metagenomes confirm the importance of specific gut bacteria in the metabolism of (1,3;1,4)-β-glucans in human diets ( Martens et al 2011 ; Tamura et al 2017 ; Déjean et al 2020 ; Singh et al 2023 ).…”

Section: Future Opportunitiesmentioning

confidence: 76%

Enzymes in 3D: Synthesis, remodelling, and hydrolysis of cell wall (1,3;1,4)-β-glucans

Hrmova,

Zimmer,

Bulone

et al. 2023

Plant Physiology

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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.

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