Genomic structure and differential expression of two tandem-arranged GSTZ genes in rice.
Genomic structure and differential expression of two tandem-arranged GSTZ genes in rice.
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DOI：
10.1016/j.gene.2004.03.020
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发表时间：
2004-06
期刊：
影响因子：
3.5
通讯作者：
Tokuji Tsuchiya;T. Takesawa;H. Kanzaki;I. Nakamura
中科院分区：
文献类型：
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作者：
Tokuji Tsuchiya;T. Takesawa;H. Kanzaki;I. Nakamura
谷胱甘肽S-转移酶（GST）是清除酶，其通过催化这些底物与三肽谷胱甘肽的缀合来解毒细胞外源性物质和毒素。GST根据基因组织和序列相似性进行分类。对水稻zeta class GST（GSTZ）基因组DNA的序列分析表明，两个同源GSTZ基因以串联方式排列，基因间存在一个短的（0.4kb）间隔区。OsGSTZ 1和OsGSTZ 2的上游和下游分别有3.5和3.2kb的9个编码外显子。OsGSTZ 1的转录本有一个长的3′非翻译区（3′ UTR），主要由第10个非编码外显子编码，而OsGSTZ 2的mRNA有一个长的5′ UTR。北方杂交分析表明，OsGSTZ 1/2在叶片中表达量较高，而在根中表达量较低。由于OsGSTZ 1/2在叶片组织中的信息仅被水处理强烈诱导，因此难以测定各种胁迫处理对OsGSTZ 1/2转录的诱导。因此，使用水稻培养细胞，我们通过实时逆转录-聚合酶链反应（RT-PCR）分析了OsGSTZ 1和OsGSTZ 2基因对各种处理的各自响应。结果表明，OsGSTZ 1基因在大肠杆菌中的表达水平约为0.001。1000-在未经胁迫处理的悬浮细胞中比OsGSTZ 2高10倍。OsGSTZ 1在各种胁迫条件下组成型表达。与此相反，OsGSTZ 2基因的表达强烈增强到30倍的茉莉酸处理。这些观察结果表明OsGSTZ 1和OsGSTZ 2基因在水稻培养细胞中的表达受到差异调节。
Glutathione S-transferases (GSTs) are scavenging enzymes that detoxify cellular xenobiotics and toxins by catalyzing the conjugation of these substrates with a tripeptide glutathione. GSTs are classified depending on gene organization and sequence similarity. The sequence analysis of genomic DNA for zeta class GST (GSTZ) locus in rice indicated that two homologous GSTZ genes lay in a tandem orientation with a short (0.4 kb) intergenic spacer. The upstream OsGSTZ1 and downstream OsGSTZ2 spanned 3.5 and 3.2 kb with nine coding exons, respectively. The transcript of OsGSTZ1 had a long 3′ untranslated region (3′ UTR) that was mostly encoded by a 10th noncoding exon, whereas OsGSTZ2 mRNA contained a long 5′ UTR. Northern blot analysis showed that OsGSTZ1/2 messages were strongly expressed in leaf blades, while transcripts from roots were low level. Because OsGSTZ1/2 messages in leaf tissues were strongly induced only by water treatment, it was difficult to assay for the induction of OsGSTZ1/2 transcripts by various stress treatments. Thus, using rice culture cells, we analyzed the respective responses of OsGSTZ1 and OsGSTZ2 genes against various treatments by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The results showed that OsGSTZ1 was expressed at a level ca. 1000-fold higher than OsGSTZ2 in suspension cells without stress treatment. OsGSTZ1 was expressed constitutively under various stress conditions. In contrast, the expression of OsGSTZ2 gene was strongly enhanced to 30-fold by treatment with jasmonic acid. These observations suggested that the expression of OsGSTZ1 and OsGSTZ2 genes are differentially regulated in the culture cell of rice.