Cançado Geraldo M A, De Rosa Vicente E, Fernandez Jorge H, Maron Lyza G, Jorge Renato A, Menossi Marcelo
Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, 13083-970, Campinas, SP, Brazil.
Centro de Toxinologia Aplicada, Instituto Butantan, 05503-900, São Paulo, SP, Brazil.
Funct Plant Biol. 2005 Nov;32(11):1045-1055. doi: 10.1071/FP05158.
Aluminum (Al) toxicity induces changes in the expression of several genes, some of which are involved in plant responses to oxidative stress. Using mRNA differential display, we identified a maize Al-inducible cDNA encoding a glutathione S-transferase (GST). The gene was named GST27.2 owing to its homology to the maize gene GST27, which is known to be induced by xenobiotics. GST27.2 is present in the maize genome as a single copy and analysis of its expression pattern revealed that the gene is expressed mainly in the root tip. Expression was up-regulated in response to various Al and Cd concentrations in both Al-tolerant and Al-sensitive maize lines. Consistent with its role in plants, phylogenetic analysis of theta-type GSTs revealed that GST27.2 belongs to a group of proteins that respond to different stresses. Finally, structural analysis of the polypeptide chain indicates that the two amino acids that differ between GST27.2 and GST27 (E102K and P123L) could be responsible for alterations in activity and / or specificity. Together, these results suggest that GST27.2 may play an important part in plant defenses against Al toxicity.
铝（Al）毒性会引发多个基因表达的变化，其中一些基因参与植物对氧化应激的反应。利用mRNA差异显示技术，我们鉴定出一个编码谷胱甘肽S-转移酶（GST）的玉米铝诱导型cDNA。由于该基因与已知受外源化合物诱导的玉米基因GST27具有同源性，故将其命名为GST27.2。GST27.2在玉米基因组中以单拷贝形式存在，对其表达模式的分析表明，该基因主要在根尖表达。在耐铝和铝敏感的玉米品系中，其表达均会因不同浓度的铝和镉而上调。与其在植物中的作用一致，对θ型GSTs的系统发育分析表明，GST27.2属于一组对不同胁迫作出反应的蛋白质。最后，对多肽链的结构分析表明，GST27.2与GST27之间存在差异的两个氨基酸（E102K和P123L）可能导致了活性和/或特异性的改变。这些结果共同表明，GST27.2可能在植物抵御铝毒性中发挥重要作用。
