Zhang Hongxiao, Lian Chunlan, Shen Zhenguo
College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Ann Bot. 2009 Apr;103(6):923-30. doi: 10.1093/aob/mcp012. Epub 2009 Feb 5.
Although copper (Cu) is an essential micronutrient for plants and algae, excess Cu is toxic to most plants and can cause a wide range of deleterious effects. To investigate the response of rice (Oryza sativa) to Cu stress, a proteomic approach was used to analyse Cu stress-induced changes in the expression of low molecular-weight proteins in germinating rice seed embryos.
Rice seeds were germinated in the presence or absence of 200 microm Cu for 6 d, and embryos, including newly formed shoots and radicles, were isolated. After proteins were extracted from the germinating embryos and separated by two-dimensional PAGE, 16 proteins in the 6- to 25-kDa range were identified using MALDI-TOF mass spectrometry.
Thirteen of the proteins identified, including metallothionein-like protein, membrane-associated protein-like protein, putative wall-associated protein kinase, pathogenesis-related proteins and the putative small GTP-binding protein Rab2, were up-regulated by Cu stress. Three proteins, a putative small cytochrome P450 (CYP90D2), a putative thioredoxin and a putative GTPase, were down-regulated by Cu stress. As far as is known, this study provides the first proteomic evidence that metallothionein and CYP90D2 are Cu-responsive proteins in plants. These findings may lead to a better understanding of plant molecular responses to toxic metal exposure.
尽管铜（Cu）是植物和藻类必需的微量营养素，但过量的铜对大多数植物有毒，并会造成一系列有害影响。为了研究水稻（Oryza sativa）对铜胁迫的响应，采用蛋白质组学方法分析了铜胁迫诱导的萌发水稻种子胚中低分子量蛋白质表达的变化。
将水稻种子在含有或不含200微摩尔铜的条件下萌发6天，分离出包括新形成的芽和胚根在内的胚。从萌发的胚中提取蛋白质并通过二维聚丙烯酰胺凝胶电泳进行分离后，使用基质辅助激光解吸电离飞行时间质谱法鉴定了6至25千道尔顿范围内的16种蛋白质。
鉴定出的13种蛋白质，包括类金属硫蛋白、膜相关蛋白样蛋白、假定的壁相关蛋白激酶、病程相关蛋白和假定的小GTP结合蛋白Rab2，在铜胁迫下上调。三种蛋白质，一种假定的小细胞色素P450（CYP90D2）、一种假定的硫氧还蛋白和一种假定的GTP酶，在铜胁迫下下调。据我们所知，本研究提供了首个蛋白质组学证据，证明金属硫蛋白和CYP90D2是植物中的铜响应蛋白。这些发现可能有助于更好地理解植物对有毒金属暴露的分子反应。
