摘要
天然橡胶在橡胶树的乳管细胞中特异性合成。用于割胶的成熟乳管与邻近的薄壁细胞之间不存在胞间连丝,故乳管的水分转入只能通过细胞膜定位的PIP水通道蛋白来实现。为探讨乳管水分平衡的分子机制,研究对1个高丰度表达的PIP基因HbPIP2;7进行了克隆,在此基础上对其编码蛋白的亚细胞定位和多聚化特性进行了分析。结果表明:HbPIP2;7的编码区全长837 bp,预测编码278 AA,理论分子量为29.56 kDa、等电点为9.11、不稳定系数为29.89、总平均疏水指数为0.526,含有1个保守的MIP结构域及6个典型的跨膜螺旋,预测以四聚体的形式起作用。生物信息学预测和在烟草中的亚细胞定位分析均显示,HbPIP2;7定位在细胞膜。双分子荧光互补和酵母双杂交实验均表明,HbPIP2;7不能形成同源多聚体,推测HbPIP2;7主要通过异源互作的方式参与橡胶树乳管的水分平衡。
Natural rubber is specifically synthesized in the laticifer of Hevea brasiliensis.Due to the absence of plasmodesmata between mature laticifer cells and surrounding parenchyma cells,water influx toward laticifers is mainly controlled by plasma membrane intrinsic proteins(PIPs) within the aquaporin(AQP) family.To investigate the molecular mechanism of water balance in laticifers,the coding sequence(CDS) of an abundant PIP gene denoted HbPIP2;7 was isolated using RT-PCR followed by subcellular localization and multimerization analyses of its coding protein.Sequence analysis revealed that the CDS length of HbPIP2;7 is 837 bp,putatively encoding278 amino acids with the theoretical molecular weight of 29.56 kDa,the isoelectric point of 9.11,the instability index of 29.89,and the grand average of hydropathicity of 0.526.The protein was shown to contain 1 conserved MIP domain with 6 transmembrane helixes and may function in tetramers.Bioinformatics prediction and transient overexpression in Nicotiana benthamiana leaves revealed that HbPIP2;7 is localized in the plasma membrane.Both bimolecular fluorescence complementation and yeast two-hybrid analyses suggested that this protein could not form a homomultimer.Thereby,HbPIP2;7 is more likely to be involved in laticifer water balance in the form of hereotetramers.
作者
邹智
郑玉皎
乔雪莹
阳江华
Zou Zhi;Zheng Yujiao;Qiao Xueying;Yang Jianghua(Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions,Institute of Tropical Bioscience and Biotechnology,Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences,Haikou Hainan 571101,China;Rubber Research Institute,Chinese Academy of Tropical Agricultural Sciences,Haikou Hainan 571101,China)
出处
《西南林业大学学报（自然科学）》
CAS
北大核心
2024年第1期1-6,共6页
Journal of Southwest Forestry University：Natural Sciences
基金
国家自然科学基金项目(31971688,31700580)资助
海南省自然科学基金项目(320RC705,319MS093)资助
中央级公益性科研院所基本科研业务费专项(1630052022001)资助。
