水稻谷氨酰半胱氨酸合成酶基因的结构和表达分析  

Structure and Expression Analysis of the Gama-glutamylcysteine Synthetase Gene in Rice

作　　者：彭凌涛[1] 王江[1] 李琳[1] 安林升[1] 张景六[1] 

机构地区：[1]中国科学院上海生命科学研究院植物生理生态研究所

出　　处：《植物生理与分子生物学学报》2004年第5期533-540,共8页Journal Of Plant Physiology and Molecular Biology

基　　金：国家重点基础研究发展规划项目(No.G1999011601);国家863项目(No.2001AA222221)~~

摘　　要：利用该实验室T-DNA标签的编号为L395的水稻突变体,克隆了一个编码水稻谷胱苷肽(GSH)合成途径中关键酶即谷氨酰半胱氨酸合成酶(GCS)的基因,将其命名为OsGCS(Genbank accession No.AJ508915)。该基因位于水稻第五染色体上,OsGCS基因含有15个外显子和14个内含子,编码492个氨基酸。该基因与拟南芥的GCS基因相比较,编码区域同源性较高,而启动子区域的序列没有显著的相似性。通过RT-PCR的方法确定OsGCS基因的转录起始位点可能位于翻译起始位点(ATG)上游211 bp处。在L395突变体中,T-DNA是单拷贝形式插入在OsGCS基因的第二内含子和外显子连接处,并且造成了3个碱基的缺失.在重金属耐受性、OsGCS基因表达以及体内GSH含量方面突变体L395和对照中花11之间没有明显的差别。Gama-glutamylcysteine synthetase (GCS) is a rate-limiting enzyme in GSH biosynthesis. The GCS gene has been cloned in Arabidopsis thaliana and other plants, but has still not been reported in rice. From rice mutant population generated from T-DNA insertion, we cloned the rice GCS gene from mutant L395 by T-DNA tag cloning method, and named it OsGCS (Genbank accession No. AJ508915). Full length OsGCS cDNA clones were obtained from a rice cDNA library by the PCR method. A comparison of the genome and cDNA sequence(Genebank accession No. AJ508916)shows that OsGCS gene is composed of 15 exons and 14 introns(Fig.2) and coding a 493-amino acid protein. The OsGCS gene is highly homologous with the AtGCS gene in the coding region but completely different in the promoter region. The putative transcription start site (TSS) confirmed by RT-PCR was located 211 bp upstream of the translation start codon 'ATG' (Fig.5). In mutant L395, a single T-DNA copy was integrated between the second intron and second exon of OsGCS gene, causing one nucleotide deletion in the second exon and two nucleotide deletions in the second intron (Fig.4). No significant differences were found in Cd^(2+) stress tolerance (Fig.6), rice GCS gene expression level (Fig.8) and GSH content (Fig.7) between mutant L395 and Zhonghua 11. It is possible that another GCS gene on chromosome 7 might complement function of OsGCS gene on chromosome 5.

关 键 词：水稻 谷氨酰半胱氨酸合成酶基因 结构分析 

分 类 号：S511[农业科学—作物学]