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-Structure paper
タイトル | Mechanism of mixed-linkage glucan biosynthesis by barley cellulose synthase-like CslF6 (1,3;1,4)-β-glucan synthase. |
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ジャーナル・号・ページ | Sci Adv, Vol. 8, Issue 45, Page eadd1596, Year 2022 |
掲載日 | 2022年11月11日 |
著者 | Pallinti Purushotham / Ruoya Ho / Long Yu / Geoffrey B Fincher / Vincent Bulone / Jochen Zimmer / |
PubMed 要旨 | Mixed-linkage (1,3;1,4)-β-glucans, which are widely distributed in cell walls of the grasses, are linear glucose polymers containing predominantly (1,4)-β-linked glucosyl units interspersed with ...Mixed-linkage (1,3;1,4)-β-glucans, which are widely distributed in cell walls of the grasses, are linear glucose polymers containing predominantly (1,4)-β-linked glucosyl units interspersed with single (1,3)-β-linked glucosyl units. Their distribution in cereal grains and unique structures are important determinants of dietary fibers that are beneficial to human health. We demonstrate that the barley cellulose synthase-like CslF6 enzyme is sufficient to synthesize a high-molecular weight (1,3;1,4)-β-glucan in vitro. Biochemical and cryo-electron microscopy analyses suggest that CslF6 functions as a monomer. A conserved "switch motif" at the entrance of the enzyme's transmembrane channel is critical to generate (1,3)-linkages. There, a single-point mutation markedly reduces (1,3)-linkage formation, resulting in the synthesis of cellulosic polysaccharides. Our results suggest that CslF6 monitors the orientation of the nascent polysaccharide's second or third glucosyl unit. Register-dependent interactions with these glucosyl residues reposition the polymer's terminal glucosyl unit to form either a (1,3)- or (1,4)-β-linkage. |
リンク | Sci Adv / PubMed:36367939 / PubMed Central |
手法 | EM (単粒子) |
解像度 | 4.0 Å |
構造データ | EMDB-27655, PDB-8dqk: |
由来 |
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キーワード | TRANSFERASE / glucan / glycosyltransferase / cellulose / barley |