Plant cell wall polysaccharides, including xylan, glucomannan, xyloglucan and pectin, are often acetylated. Although a number of acetyltransferases responsible for the acetylation of some of these polysaccharides have been biochemically characterized, little is known about the source of acetyl donors and how acetyl donors are translocated into the Golgi, where these polysaccharides are synthesized. In this report, we investigated roles of ATP-citrate lyase (ACL) that generates cytosolic acetyl-CoA in cell wall polysaccharide acetylation and effects of simultaneous mutations of four Reduced Wall Acetylation (RWA) genes on acetyl-CoA transport into the Golgi in Arabidopsis thaliana. Expression analyses of genes involved in the generation of acetyl-CoA in different subcellular compartments showed that the expression of several ACL genes responsible for cytosolic acetyl-CoA synthesis was elevated in interfascicular fiber cells and induced by secondary wall-associated transcriptional activators. Simultaneous downregulation of the expression of ACL genes was demonstrated to result in a substantial decrease in the degree of xylan acetylation and a severe alteration in secondary wall structure in xylem vessels. In addition, the degree of acetylation of other cell wall polysaccharides, including glucomannan, xyloglucan and pectin, was also reduced. Moreover, Golgi-enriched membrane vesicles isolated from the rwa1/2/3/4 quadruple mutant were found to exhibit a drastic reduction in acetyl-CoA transport activity compared with the wild type. These findings indicate that cytosolic acetyl-CoA generated by ACL is essential for cell wall polysaccharide acetylation and RWAs are required for its transport from the cytosol into the Golgi.

中文翻译：

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ATP柠檬酸裂解酶产生的胞质乙酰辅酶A对乙酰化细胞壁多糖至关重要。

植物细胞壁多糖，包括木聚糖，葡甘露聚糖，木葡聚糖和果胶，通常被乙酰化。尽管已对一些其中一些多糖进行乙酰化的乙酰转移酶进行了生物化学表征，但对乙酰基供体的来源以及乙酰基供体如何转移到高尔基体中的了解甚少，在这些高尔基体中合成了这些多糖。在本报告中，我们研究了在细胞壁多糖乙酰化中产生胞质乙酰辅酶A的ATP柠檬酸裂合酶（ACL）的作用以及乙酰基辅酶A转运到拟南芥中高尔基体的四个还原壁乙酰化（RWA）基因的同时突变的影响。拟南芥。在不同的亚细胞区室中参与乙酰辅酶A产生的基因的表达分析表明，负责胞浆乙酰辅酶A合成的几个ACL基因的表达在束间纤维细胞中升高，并由次生壁相关的转录激活因子诱导。ACL基因表达的同时下调被证明导致木聚糖乙酰化程度的大幅下降和木质部血管中次生壁结构的严重改变。另外，还降低了其他细胞壁多糖，包括葡甘露聚糖，木葡聚糖和果胶的乙酰化程度。而且，发现与野生型相比，从rwa1 / 2/3/4四倍体突变体分离的高尔基体富集的膜囊泡显示乙酰CoA转运活性急剧降低。这些发现表明，ACL产生的胞质乙酰辅酶A对细胞壁多糖乙酰化至关重要，而RWA则需要将其从胞质溶胶转运到高尔基体中。