Acetylesterase-Mediated Deacetylation of Pectin Impairs Cell Elongation, Pollen Germination, and Plant Reproduction
Acetylesterase-Mediated Deacetylation of Pectin Impairs Cell Elongation, Pollen Germination, and Plant Reproduction
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DOI：
10.1105/tpc.111.092411
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发表时间：
2012-01-01
期刊：
影响因子：
11.6
通讯作者：
Liu, Chang-Jun
中科院分区：
文献类型：
--
作者：
Gou, Jin-Ying;Miller, Lisa M.;Liu, Chang-Jun
果胶是高等植物初生细胞壁的主要成分。果胶多糖主链中的一些半乳糖醛酸残基通常在C-2或C-3位置被O-乙酰化，并且所产生的乙酰酯在植物生长和发育过程中动态变化。该过程涉及酶促乙酰化和脱乙酰化。通过基因组序列分析，从黑杨中鉴定出一种果胶乙酰酯酶（PAE 1）。重组Pt PAE 1在体外表现出优先释放甜菜（甜菜）和马铃薯（马铃薯）果胶中的乙酸酯部分的活性。在烟草中过表达Pt PAE 1降低了果胶的乙酰酯的水平，但木聚糖没有。脱乙酰化引起细胞壁多糖的组成和/或结构的差异变化，随后损害了花柱和花丝的细胞伸长，花粉粒的萌发和花粉管的生长。因此，过表达PAE 1的植物表现出严重的雄性不育。此外，与传统观点相反，PAE 1介导的脱乙酰化显著降低了果胶的消化率。我们的数据表明，果胶乙酰酯酶的功能作为一个重要的结构调节剂在植物通过调节果胶乙酰化的精确状态，影响细胞壁的多糖的重塑和理化性质，从而影响细胞的可扩展性。
Pectin is a major component of the primary cell wall of higher plants. Some galacturonyl residues in the backbone of pectinaceous polysaccharides are often O-acetylated at the C-2 or C-3 position, and the resulting acetylesters change dynamically during the growth and development of plants. The processes involve both enzymatic acetylation and deacetylation. Through genomic sequence analysis, we identified a pectin acetylesterase (PAE1) from black cotton-wood (Populus trichocarpa). Recombinant Pt PAE1 exhibited preferential activity in releasing the acetate moiety from sugar beet (Beta vulgaris) and potato (Solanum tuberosum) pectin in vitro. Overexpressing Pt PAE1 in tobacco (Nicotiana tabacum) decreased the level of acetyl esters of pectin but not of xylan. Deacetylation engendered differential changes in the composition and/or structure of cell wall polysaccharides that subsequently impaired the cellular elongation of floral styles and filaments, the germination of pollen grains, and the growth of pollen tubes. Consequently, plants overexpressing PAE1 exhibited severe male sterility. Furthermore, in contrast to the conventional view, PAE1-mediated deacetylation substantially lowered the digestibility of pectin. Our data suggest that pectin acetylesterase functions as an important structural regulator in planta by modulating the precise status of pectin acetylation to affect the remodeling and physiochemical properties of the cell wall's polysaccharides, thereby affecting cell extensibility.