Starch synthase II plays a crucial role in starch biosynthesis and the formation of multienzyme complexes in cassava storage roots
Starch synthase II plays a crucial role in starch biosynthesis and the formation of multienzyme complexes in cassava storage roots
复制标题
淀粉合酶 II 在木薯贮藏根中淀粉生物合成和多酶复合物的形成中起着至关重要的作用
DOI：
10.1093/jxb/erac022
复制
发表时间：
2022-02-04
影响因子：
6.9
通讯作者：
Zhang, Peng
中科院分区：
文献类型：
--
作者：
He, Shutao;Hao, Xiaomeng;Zhang, Peng
在这里，我们重点关注淀粉合成酶II，以阐明其对淀粉生物物理特性的影响以及对木薯储藏根中淀粉合成酶复合物组织的影响。淀粉是由绿色植物合成的葡萄糖聚合物，用于能量储存，对植物生长至关重要和繁殖。淀粉多糖的生物合成由大淀粉合成酶（SS）蛋白超家族成员介导。在这里，我们表明，在木薯贮藏根，可溶性淀粉合成酶II（MeSSII）在淀粉的生物合成和蛋白质复合物的形成与其他淀粉生物合成酶直接相互作用MeSSI，MeSBEII，和MeISAII中起着重要的作用。MeSSII-RNAi木薯品系在其贮藏根中表现出增加的直链淀粉含量和减少的支链淀粉中间链（B1型）的生物合成，从而导致淀粉物理化学性质的改变。此外，凝胶渗透色谱分析野生型和MeSSII-RNAi株系之间的淀粉生物合成酶证实了MeSSII在异聚淀粉合成蛋白复合物的组织中的关键作用。木薯中MeSSII的缺乏也降低了MeSSI、MeSBEII、MeISAI和MeISAII与淀粉颗粒结合的能力。这些发现揭示了块根作物淀粉生物合成机制的关键组成部分。
Here, we focus on starch synthase II to elucidate its impact on the biophysical properties of starch and its influence on the organization of the starch synthase complexes in cassava storage roots.Starch is a glucose polymer synthesized by green plants for energy storage and is crucial for plant growth and reproduction. The biosynthesis of starch polysaccharides is mediated by members of the large starch synthase (SS) protein superfamily. Here, we showed that in cassava storage roots, soluble starch synthase II (MeSSII) plays an important role in starch biosynthesis and the formation of protein complexes with other starch biosynthetic enzymes by directly interacting with MeSSI, MeSBEII, and MeISAII. MeSSII-RNAi cassava lines showed increased amylose content and reduced biosynthesis of the intermediate chain of amylopectin (B1 type) in their storage roots, leading to altered starch physicochemical properties. Furthermore, gel permeation chromatography analysis of starch biosynthetic enzymes between wild type and MeSSII-RNAi lines confirmed the key role of MeSSII in the organization of heteromeric starch synthetic protein complexes. The lack of MeSSII in cassava also reduced the capacity of MeSSI, MeSBEII, MeISAI, and MeISAII to bind to starch granules. These findings shed light on the key components of the starch biosynthesis machinery in root crops.