Morris Phillip, Dalton Sue, Langdon Tim, Hauck Barbara, de Buanafina Marcia M O
Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Wales, UK.
Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Plas Gogerddan, Aberystwyth, SY23 3EB Wales, UK.
Plant Cell Tissue Organ Cult. 2017;129(2):181-193. doi: 10.1007/s11240-017-1168-9. Epub 2017 Feb 7.
In the cell walls of grasses ferulic acid is esterified to arabinosyl residues in arabinoxylans that can then undergo oxidative coupling reactions to form ferulate dehydrodimers, trimers and oligomers which function to cross-link cell-wall polysaccharides, limiting cell wall degradability. Fungal ferulic acid esterase can release both esterified monomeric and dimeric ferulic acids from these cell wall arabinoxylans making the cell wall more susceptible to further enzymatic attack and increasing cell wall degradability. Non-embryogenic cell suspension cultures of expressing a ferulic acid esterase () targeted to either the apoplast, or endoplasmic reticulum under the control of a constitutive actin promoter, or to the vacuole under the control of a soybean heat shock promoter, were established and FAE activity determined in the cells and medium during a growth cycle. Analysis of the ester-linked ferulates of the cell walls showed that all three transformed cell lines had both reduced ferulate levels and increased levels of xylanase mediated release of wall phenolics on autodigestion as well as increased rates of cell wall digestion in a simulated rumen environment, when compared to control non-transformed cells.
在禾本科植物的细胞壁中，阿魏酸被酯化为阿拉伯木聚糖中的阿拉伯糖基残基，然后可发生氧化偶联反应，形成阿魏酸脱氢二聚体、三聚体和寡聚体，这些物质起到交联细胞壁多糖的作用，限制细胞壁的可降解性。真菌阿魏酸酯酶可从这些细胞壁阿拉伯木聚糖中释放出酯化的单体和二聚体阿魏酸，使细胞壁更容易受到进一步的酶攻击，并提高细胞壁的可降解性。建立了在组成型肌动蛋白启动子控制下靶向质外体或内质网、或在大豆热激启动子控制下靶向液泡的表达阿魏酸酯酶（）的非胚性细胞悬浮培养物，并在生长周期中测定细胞和培养基中的FAE活性。对细胞壁中酯键连接的阿魏酸的分析表明，与对照未转化细胞相比，所有三种转化细胞系的阿魏酸水平均降低，自消化时木聚糖酶介导的细胞壁酚类物质释放水平增加，并且在模拟瘤胃环境中细胞壁消化速率提高。
