Abstract：
Mucilage is a gelatinous and sticky hydrophilic polysaccharide released from epidermal cells of seed coat after the hydration of mature seeds and is composed primarily of unbranched rhamnogalacturonan I (RG-I). In this study, we produced a recombinant endo-RG-I hydrolase from Aspergillus aculeatus (AaRhgA) in the fission yeast Schizosaccharomyces pombe and examined its substrate preference for pyridylaminated (PA) RG-I with the various degrees of polymerization (DP). Recombinant AaRhgA requires PA-RG-I with a DP of 10 or higher for its hydrolase activity. We heterologously expressed the AarhgA gene under the strong constitutive promoter, cauliflower mosaic virus 35S promoter, in Arabidopsis thaliana. In a series of biochemical analyses of each mucilage fraction released from the water-imbibed seeds of the transgenic plants, we found the enhanced deposition of the transparent mucilage layer that existed in the peripheral regions of the adherent mucilage and was not stained with ruthenium red. This study demonstrated the feasibility of manipulating the mucilage organization by heterologous expression of the endo-RG-I hydrolase.
摘要：
胶浆是成熟种子水合后从种皮的表皮细胞释放的凝胶状且粘稠的亲水性多糖，主要由无分支的鼠李糖半乳糖醛酸I（RG-I）组成。在这项研究中,我们在裂殖酵母裂殖酵母中从刺曲霉（AaRhgA）中生产了重组内切RG-I水解酶，并检查了其对具有各种聚合度（DP）的吡啶基胺化（PA）RG-I的底物偏好。重组AaRhgA的水解酶活性需要DP为10或更高的PA-RG-I。我们在强组成型启动子下异源表达AarhgA基因，花椰菜花叶病毒35S启动子,拟南芥。在对从转基因植物的吸水种子中释放的每个粘液部分进行的一系列生化分析中，我们发现透明粘液层的沉积增强，该粘液层存在于粘附粘液的周围区域，并且未被钌红染色。这项研究证明了通过异源表达endo-RG-I水解酶来操纵粘液组织的可行性。
