Rice HYDROPEROXIDE LYASES with unique expression patterns generate distinct aldehyde signatures in Arabidopsis
Rice HYDROPEROXIDE LYASES with unique expression patterns generate distinct aldehyde signatures in Arabidopsis
复制标题
DOI：
10.1104/pp.106.078592
复制
发表时间：
2006-05-01
期刊：
影响因子：
7.4
通讯作者：
Dehesh, K
中科院分区：
文献类型：
--
作者：
Chehab, EW;Raman, G;Dehesh, K
氢过氧化物裂解酶（HPL）基因编码催化脂肪酸氢过氧化物裂解成醛和氧酸的酶。水稻（Oryza sativa）中有三种HPLs，命名为OsHPL1至OsHPL3。为了探索这些基因之间差异功能活动的可能性，我们研究了它们的表达模式和编码产物的生化特性。转录分析表明，这些基因具有不同的表达模式和水平。OsHPL1普遍表达，OsHPL2在叶片和叶鞘中表达，而OsHPL3是伤口诱导的，仅在叶片中表达。通过使用9-/13-羟基过氧亚油酸和9-/13-羟基过氧亚油酸作为底物的体外酶测定，OsHPLs对底物的偏好也有所不同。OsHPL1和OsHPL2代谢9-/13-氢过氧化物，而OsHPL3只代谢13-氢过氧化物亚麻酸。HPL酶的序列比对已经确定了可能负责这些酶的底物特异性/偏好的特征残基。通过叶绿体导入试验和绿色荧光蛋白（GFP）融合研究确定，所有三种OsHPLs都是叶绿体定位的。在过表达OsHPL-GFP融合体的转基因拟南芥（Arabidopsis thaliana）植株中进行的醛测量表明，所有水稻HPLs在异源系统中都具有功能，并且每种HPLs都产生不同的代谢物特征。有趣的是，这些醛只在叶子中检测到，而在根中检测不到，尽管两种组织中OsHPL-GFP蛋白的水平相似。同样，尽管存在OsHPL1转录本，但在水稻根系中检测不到醛的水平。总之，这些数据表明，除了转录物和HPL酶丰度之外，还有其他组织特异性机制调节HPL衍生代谢物的水平。
HYDROPEROXIDE LYASE (HPL) genes encode enzymes that catalyze the cleavage of fatty acid hydroperoxides into aldehydes and oxoacids. There are three HPLs in rice (Oryza sativa), designated OsHPL1 through OsHPL3. To explore the possibility of differential functional activities among these genes, we have examined their expression patterns and biochemical properties of their encoded products. Transcript analysis indicates that these genes have distinct patterns and levels of expression. OsHPL1 is ubiquitously expressed, OsHPL2 is expressed in the leaves and leaf sheaths, whereas OsHPL3 is wound inducible and expressed exclusively in leaves. OsHPLs also differ in their substrate preference as determined by in vitro enzyme assays using 9-/13-hydroperoxy linolenic and 9-/13-hydroperoxy linoleic acids as substrates. OsHPL1 and OsHPL2 metabolize 9-/13-hydroperoxides, whereas OsHPL3 metabolizes 13-hydroperoxy linolenic acid exclusively. Sequence alignments of the HPL enzymes have identified signature residues potentially responsible for the substrate specificity/preference of these enzymes. All three OsHPLs are chloroplast localized as determined by chloroplast import assays and green fluorescent protein (GFP) fusion studies. Aldehyde measurements in transgenic Arabidopsis (Arabidopsis thaliana) plants overexpressing individual OsHPL-GFP fusions indicate that all rice HPLs are functional in a heterologous system, and each of them generates a distinct signature of the metabolites. Interestingly, these aldehydes were only detectable in leaves, but not in roots, despite similar levels of OsHPL-GFP proteins in both tissues. Similarly, there were undetectable levels of aldehydes in rice roots, in spite of the presence of OsHPL1 transcripts. Together, these data suggest that additional tissue-specific mechanism(s) beyond transcript and HPL enzyme abundance, regulate the levels of HPL-derived metabolites.