Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, Lobachevsky Str. 2/31, P.O. Box 30, 420111 Kazan, Russian Federation.
Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, Lobachevsky Str. 2/31, P.O. Box 30, 420111 Kazan, Russian Federation.
Carbohydr Polym. 2017 Feb 20;158:93-101. doi: 10.1016/j.carbpol.2016.11.082. Epub 2016 Nov 29.
Within the family of plant cell wall polysaccharides rhamnogalacturonans I are the most diverse and structurally complex members. In present study we characterize the 3-dimensional structures and dynamic features of the constituents of RG-I along MD trajectories. It is demonstrated that extended threefold helical structure of the rhamnogalacturonan linear backbone is the most energetically favorable motif. Branching helps to stabilize a conformer of the backbone twisted along 1→2 glycosidic linkage triggering the orientation of long side chains without altering the extended overall backbone chain conformation. Formation of anti-parallel pairing of the β-galactan side chains allows us to suggest a novel mode of non-covalent cross-linking in pectins. Studied structural elements are organized to report the first attempt to characterize 3D structure of RG-I focusing on the special case of flax tertiary cell wall and elucidate the structural basis underlying the formation of RG-I self-associates and functional role of RG-I in planta.
在植物细胞壁多糖鼠李半乳糖醛酸聚糖 I 家族中，它们是最多样化和结构最复杂的成员。在本研究中，我们沿着 MD 轨迹对 RG-I 成分的三维结构和动态特征进行了表征。结果表明，伸展的三重螺旋结构是最具能量优势的鼠李半乳糖醛酸线性主链基序。支化有助于稳定沿 1→2 糖苷键扭曲的主链构象，从而引发长侧链的取向，而不改变伸展的整体主链链构象。β-半乳糖侧链的反平行配对的形成允许我们提出果胶中非共价交联的新方式。研究的结构元素被组织起来，以报告首次尝试对 RG-I 的三维结构进行特征描述，重点是亚麻三级细胞壁的特殊情况，并阐明 RG-I 自组装形成的结构基础和其在植物中的功能作用。
