辣椒疫霉纤维素合酶复合体的组装机制和生化特征

纤维素是卵菌细胞壁的重要成分，主要由纤维素合酶复合体催化UDPG，合成β-1,4-糖苷链聚合形成，其在卵菌的生长发育和侵染过程中具有重要作用，目前已成为国际上探求新型卵菌抑制剂作用靶标的研究热点。迄今关于卵菌纤维素合酶的研究甚少，申请者前期开展了辣椒疫霉纤维素合酶的探索性研究，明确了纤维素合酶具有四个亚基，且CESA1，CESA2和CESA4结构相似，推测在参与纤维素合酶复合体组装和行使功能方面存在冗余；蛋白组学研究发现，CESA1在辣椒疫霉游动孢子和菌丝阶段均有表达，推测其参与了细胞壁形成。本研究拟以辣椒疫霉纤维素合酶复合体组装机制和生化特征为核心，探究纤维素合酶复合体亚基的存在形式；明确纤维素合酶不同亚基及合酶复合体的催化活性和生化特征；揭示辣椒疫霉纤维素的生物合成机制。该研究有望填补卵菌多糖转移酶（GT）家族研究领域的空白，可为基于纤维素合酶的分子靶标为导向的新药物创制提供理论基础。

The oomycete cell wall mainly consists of cellulose. The cellulose synthase complex (CSCs) which catalyzes UDPG to β-1,4-glucan chains, and plays an important role in oomycetes growth and infection of plants, is currently the subject of intensive investigation for potentive targets of fungicides. Up to now, oomycetes cellulose synthases were poorly studied. We have carried out a preliminary study on Phytophthora capsici cellulose synthases. Our results showed cellulose synthase proteins had four isoforms: CESA1, CESA2, CESA3, and CESA4. In addition, CESA1, CESA2, and CESA4 shared the same domains. It was suggested that CESA1, CESA2, and CESA4 were rebundant in assembling of cellulose synthase complex. In addition, previous proteomics study revealed CESA1 was expressed in both mycelium and cysts. This suggested CESA1 played an important role in cell wall biosynthesis. In our study, we will focus on the assemble mechanism and biochemical function of oomycete cellulose synthase complex, with aim to study the existing form of oomycete cellulose synthase complex. In addition, the activity and biochemical characterization of CSCs and individual cellulose synthase proteins will be clarified. This will illustrate the mechanism of cellulose biosynthesis. The study will provide important information of oomycete GT studies, and inform the design of inhibitors to control oomycete infection and growth.