A gene from the cellulose synthase-like C family encodes a β-1,4 glucan synthase
A gene from the cellulose synthase-like C family encodes a β-1,4 glucan synthase
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DOI：
10.1073/pnas.0703133104
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发表时间：
2007-05-15
影响因子：
11.1
通讯作者：
Wilkerson, Curtis G.
中科院分区：
文献类型：
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作者：
Cocuron, Jean-Christophe;Lerouxel, Olivier;Wilkerson, Curtis G.
尽管木葡聚糖（XyG）在植物细胞壁结构和功能中起着重要作用，但其生物合成的重要细节尚不清楚。为了鉴定负责合成XyG的β-1，4葡聚糖骨架的基因，我们利用了旱金莲（Tropaeophelus majus）种子发育的特性。在旱金莲种子成熟的最后阶段，大量的XyG作为储备多糖沉积。从XyG沉积过程中分离的mRNA产生cDNA文库，并测定10，000个cDNA克隆的部分序列。发现来自纤维素酶样（CSL）基因大家族的C亚家族的单个成员在cDNA文库中过度表达。该基因在巴斯德毕赤酵母中的异源表达导致β-1，4葡聚糖的产生，证实了CSLC蛋白具有葡聚糖合酶活性。拟南芥CSLC 4基因是与旱金莲属CSL基因序列相似性最高的基因，与其他参与XyG生物合成的基因协同表达。这些和其他观察结果提供了一个令人信服的情况下，CSLC基因家族编码的蛋白质，合成XyG骨架。
Despite the central role of xyloglucan (XyG) in plant cell wall structure and function, important details of its biosynthesis are not understood. To identify the gene responsible for synthesizing the beta-1,4 glucan backbone of XyG, we exploited a property of nasturtium (Tropaeolum majus) seed development. During the last stages of nasturtium seed maturation, a large amount of XyG is deposited as a reserve polysaccharide. A cDNA library was produced from mRNA isolated during the deposition of XyG, and partial sequences of 10,000 cDNA clones were determined. A single member of the C subfamily from the large family of cellulose synthase-like (CSL) genes was found to be overrepresented in the cDNA library. Heterologous expression of this gene in the yeast Pichia pastoris resulted in the production of a beta-1,4 glucan, confirming that the CSLC protein has glucan synthase activity. The Arabidopsis CSLC4 gene, which is the gene with the highest sequence similarity to the nasturtium CSL gene, is coordinately expressed with other genes involved in XyG biosynthesis. These and other observations provide a compelling case that the CSLC gene family encode proteins that synthesize the XyG backbone.