油茶种子水通道蛋白CoPIP1-1的鉴定与分析  

Identification and Analysis of an Aquaporin(CoPIP1-1) in the Seeds of Camellia oleifera

作　　者：胡孝义[1] 谭晓风[1] 田晓明[1] 刘巧[1] 罗茜[1] 陈鸿鹏[1] 胡芳名[1] 

机构地区：[1]中南林业科技大学经济林育种与栽培国家林业局重点实验室,长沙410004

出　　处：《林业科学》2008年第12期48-56,共9页Scientia Silvae Sinicae

基　　金：中南林业科技大学研究生创新基金(2006bx01);湖南省教育厅研究生创新基金;国家"十一五"科技支撑项目(2006BAD18B0204;2006BAD01A1706)

摘　　要：以构建的油茶cDNA文库为基础,采用交错延伸PCR技术,分离克隆到一个水通道蛋白基因的编码序列(coding sequence,CDS),它编码一个287aa的跨膜蛋白(GenBank蛋白质id:ACF39901)。该蛋白可能由2条基因(GenBank登录号:EU850810、EU850811)编码,这2个基因具有相同的CDS和3′-UTR,但5′-UTR不同,其中之一多了2个小的插入片段。经对该蛋白的同源性比对和特征性基序分析,推测这个水通道蛋白属于质膜内在蛋白成员,定名为CoPIP1-1。通过同源建模,论证CoPIP1-1的水通道活性与通道口的(去)覆盖有关。N端与D环、B环的静电势作用导致了对通道口的(去)覆盖,并受磷酸化/质子化门控机制调控,质子化抑制通道活性,磷酸化则解除抑制。从同源建模的结果和细胞内的氧化状态推测该蛋白为组成型的低活性,这可能是油茶种子近成熟期脱水的成因之一。Based on a constructed cDNA library, of Camellia oleifera, a complete coding sequence （CDS） encoding a transmembrane aquaporin（AQP） （GenBank protein id： ACF39901）, which contains 287 amino acids, was separated and cloned from nearly matured seeds of C. oleifera, by overlapping extension PCR technique. This aquaporin may be translated from two AQP genes（GenBank accession No： EU850810, EU850811）, which contain the same CDS and 3＇-UTR, whereas their 5＇-UTRs are different. One of them has two additional small insertion segments compared with the other gene. By homology alignment and characteristic sequence analysis, it is speculated that this aquaporin belongs to plasma membrane intrinsic protein, designated as CoPIP1-1.By homology modeling, its water channel activity is demonstrated to be affected by the （free） covering of channel mouth caused by electrostatic potential interaction between the N terminus and D loop or B loop. This interaction is regulated by the protonization and phosphorylation gating mechanism, protonization repressing the channel activity by coverage of channel mouth, whereas phosphorylation derepressing the coverage. The results of homology modeling and intracellular oxidative stage of the C. oleifera seeds suggest that the water transport activity of CoPIP1-1 may be constitutively lower, which may be the reason for the seed desiccation during ripening.

关 键 词：油茶 水通道蛋白基因 CDNA文库 水通道活性 生物信息学 同源建模 

分 类 号：S718.46[农业科学—林学] Q943.2[生物学—植物学]