白花柽柳质膜水孔蛋白基因克隆及序列分析

Cloning and sequence analysis of gene encoding plasma aquaporin of Tamarix albiflonum

植物水孔蛋白在植物体内形成水选择性运输通道,在植物种子萌发、细胞伸长、气孔运动、受精等过程中调节水分的快速跨膜运输。有的水孔蛋白还在干旱胁迫应答中起重要作用。本文根据白花柽柳的PEG6000胁迫处理构建的SSH消减文库的水孔蛋白基因表达序列标签(EST),设计基因特异性引物进行5′RACE,克隆出一个1043bp的核苷酸序列。应用生物信息学软件进行分析,预测该序列编码287个氨基酸,具有6个跨膜区,有MIP家族信号序列SGXHXN-PAVT,高等植物PIP高度保守序列GGGANXXXXGY和TGI/TNPARSL/FGAAI/VI/VF/YN,这是质膜水孔蛋白基因的典型的结构特征。经NCBI比对,与Arabidopsis thaliana(MIP-C),同源性达到95%,预测该蛋白的相对分子量是30·9KD,理论等电点是8·84。

Plant aquaporins are water-selected-channels in plants and are involved in seed germination, cell elongation, stoma movement, fertilization and so on. Some plant aquaporins also play an important role in response to drought stress. In this paper the gene encoding the Tamarix albiflonurn Aquaporin （AQP） was amplified by 5＇rapid amplification of eDNA end （RACE） based on the sequence information obtained from the expressed sequence tag of subtractive hybridization library constructed under PEG6000 stress. The eDNA of the Tamarix albiflonum AQP gene is 1043 bp long, encoding a protein of 287 amino acids with a predicted molecular mass of 30.9KDa, has 6 transmembrane regions, and possessing the MIP family signal consensus sequence SGXHXNPAVT and the higher plant PIP highly conservative sequence GGGANXXXXGY and TGI/TNPARSL/FGAAI/VI/VF/YN. A comparative molecular analysis of nucleotide sequence in NCBI databases showed that it shared 95% homology with the gene of Arabidopsis thaliana （ MIP-C ）, with a theoretical isoelectric point of 8.84.