XYLOGLUCAN ENDOTRANSGLYCOSYLASE AND PLANT-GROWTH
XYLOGLUCAN ENDOTRANSGLYCOSYLASE AND PLANT-GROWTH
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DOI：
10.1093/jxb/45.special_issue.1693
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发表时间：
1994-11-01
影响因子：
6.9
通讯作者：
ROBINSON, S
中科院分区：
文献类型：
--
作者：
DESILVA, J;ARROWSMITH, D;ROBINSON, S
木葡聚糖内转糖基酶 (XET) 催化木葡聚糖分子的断裂和重新连接。它可能参与植物生长，起到将新合成的木葡聚糖聚合物锚定到细胞壁中或可逆地松弛纤维素-木葡聚糖网络的作用，从而允许膨压驱动的细胞扩张。与生长中的作用一致，XET 活性水平已被证明与玉米根等伸长相关（Pritchard 等，1993）。我们的小组最近从旱金莲中分离出一个 cDNA 克隆（de Silva 等，1993），编码具有 XET 活性的种子酶（Edwards 等，1986；Fanutti 等，1993）。 XET的生物学功能正在通过体内操作进行研究。我们使用旱金莲序列从番茄中分离出几个cDNA克隆，其编码的多肽序列与旱金莲XET表现出大约40%的同源性。大肠杆菌中的异源表达已用于确认 XET 活性。 XET 的同种型已从番茄果实中纯化出来，并产生了多克隆抗体。抗体和基因特异性核酸探针分别用于监测 XET 蛋白和 mRNA 水平的发育变化。初步结果表明，番茄 XET 由一系列基因编码，这些基因表现出不同的发育表达模式。番茄的农杆菌转化是使用金莲花cDNA（有义方向）和在组成型启动子控制下的果实表达的番茄cDNA（反义方向）进行的。改变 XET 水平的表型后果正在研究中。
Xyloglucan endotransglycosylase (XET) catalyses the breaking and re-joining of xyloglucan molecules. It may be involved in plant growth, functioning either to anchor newly synthesized xyloglucan polymers into the cell wall or to reversibly loosen the cellulose-xyloglucan network permitting turgor-driven cell expansion. Consistent with a role in growth, levels of XET activity have been shown to correlate with elongation in, for example, maize roots (Pritchard et al., 1993). Our group has recently isolated a cDNA clone from nasturtium (de Silva et al., 1993) encoding a seed enzyme with XET activity (Edwards et al., 1986; Fanutti et al., 1993). The biological function of XET is being investigated via in vivo manipulation.We have used the nasturtium sequence to isolate several cDNA clones from tomato whose encoded polypeptide sequences exhibit approximately 40% homology with nasturtium XET. Heterologous expression in E. coli has been used to confirm XET activity. An isoform of XET has been purified from tomato fruit and a polyclonal antibody raised. The antibody and gene-specific nucleic acid probes are being used to monitor developmental changes in XET protein and mRNA levels, respectively. Preliminary results suggest that tomato XET is encoded by a family of genes which show different developmental patterns of expression. Agrobacterium transformation of tomato has been carried out using the nasturtium cDNA (sense orientation) and a fruit-expressed tomato cDNA (antisense orientation) under the control of a constitutive promoter. The phenotypic consequences of altering levels of XET are being investigated.