Here, we present a study into the mechanisms of primary cell wall cellulose formation in grasses, using the model cereal grass Brachypodium distachyon. The exon found adjacent to the BdCESA1 glycosyltransferase QXXRW motif was targeted using Targeting Induced Local Lesions in Genomes (TILLING) and sequencing candidate amplicons in multiple parallel reactions (SCAMPRing) leading to the identification of the Bdcesa1 S830N allele. Plants carrying this missense mutation exhibited a significant reduction in crystalline cellulose content in tissues that rely on the primary cell wall for biomechanical support. However, Bdcesa1 S830N plants failed to exhibit the predicted reduction in plant height. In a mechanism unavailable to eudicotyledons, B. distachyon plants homozygous for the Bdcesa1 S830N allele appear to overcome the loss of internode expansion anatomically by increasing the number of nodes along the stem. Stem biomechanics were resultantly compromised in Bdcesa1 S830N . The Bdcesa1 S830N missense mutation did not interfere with BdCESA1 gene expression. However, molecular dynamic simulations of the CELLULOSE SYNTHASE A (CESA) structure with modelled membrane interactions illustrated that Bdcesa1 S830N exhibited structural changes in the translated gene product responsible for reduced cellulose biosynthesis. Molecular dynamic simulations showed that substituting S830N resulted in a stabilizing shift in the flexibility of the class specific region arm of the core catalytic domain of CESA, revealing the importance of this motion to protein function.

中文翻译：

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生化和生理柔韧性伴随着短孢菌cesa1 S830N中纤维素生物合成的减少。

在这里，我们使用模型谷物草Brachypodium distachyon对草中主要细胞壁纤维素形成的机理进行了研究。使用基因组中的靶向诱导局部病变（TILLING）靶向BdCESA1糖基转移酶QXXRW基序附近的外显子，并在多个平行反应（SCAMPRing）中对候选扩增子进行测序，从而鉴定Bdcesa1 S830N等位基因。携带这种错义突变的植物在依赖于原始细胞壁作为生物力学支持的组织中，结晶纤维素含量显着降低。但是，Bdcesa1 S830N植物未能表现出预期的株高下降。在双子叶植物无法利用的机制中，B。Bdcesa1 S830N等位基因纯合的distachyon植物似乎通过增加沿茎的节数而在解剖学上克服了节间扩展的损失。结果表明，干生物力学在Bdcesa1 S830N中受损。Bdcesa1 S830N错义突变不干扰BdCESA1基因表达。但是，具有模拟的膜相互作用的纤维素合成酶A（CESA）结构的分子动力学模拟表明Bdcesa1 S830N在负责减少纤维素生物合成的翻译基因产物中显示出结构变化。分子动力学模拟表明，取代S830N会导致CESA核心催化结构域的特定类区域臂的灵活性发生稳定变化，从而揭示了该运动对蛋白质功能的重要性。