NADPH-dependent Reductases Involved in the Detoxification of Reactive Carbonyls in Plants
NADPH-dependent Reductases Involved in the Detoxification of Reactive Carbonyls in Plants
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DOI：
10.1074/jbc.m110.202226
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发表时间：
2011-03-04
影响因子：
4.8
通讯作者：
Sugimoto, Yukihiro
中科院分区：
文献类型：
--
作者：
Yamauchi, Yasuo;Hasegawa, Ayaka;Sugimoto, Yukihiro
活性羰基，特别是通过脂质过氧化产生的α、β -不饱和羰基，破坏生物分子，如蛋白质和核苷酸；因此，消除这些羰基对于维持细胞稳态至关重要。在本研究中，我们重点研究了植物中nadph依赖的活性羰基解毒过程，并探索了参与该解毒过程的酶系统。以丙烯醛（CH2 = CHCHO）为模型α， β -不饱和羰基，我们从黄瓜叶片中纯化了一种主要的nadph依赖的丙烯醛还原酶，我们鉴定了该酶是一种烯醛/一氧化还原酶（AOR），催化α， β -不饱和键的还原。对编码AOR的cDNA的克隆表明，黄瓜含有两种不同的AOR，即叶绿体AOR和细胞质AOR。在包括拟南芥在内的多种植物中发现了黄瓜AOR的同源物，我们证实了拟南芥的同源物（At1g23740）也具有AOR活性。系统发育分析表明，这些AORs属于一类新的AORs。它们优先还原-不饱和酮而不是-不饱和醛。此外，我们根据生物信息学信息选择了参与nadph依赖性羰基还原的其他类别的酶，我们发现醛酮还原酶（At2g37770）和醛还原酶（At1g54870和At3g04000）与叶绿体中饱和醛和甲基乙二醛以及α， β -不饱和醛的醛基还原有关。这些结果表明，不同种类的nadph依赖性还原酶协同促进活性羰基的解毒。
Reactive carbonyls, especially alpha,beta-unsaturated carbonyls produced through lipid peroxidation, damage biomolecules such as proteins and nucleotides; elimination of these carbonyls is therefore essential for maintaining cellular homeostasis. In this study, we focused on an NADPH-dependent detoxification of reactive carbonyls in plants and explored the enzyme system involved in this detoxification process. Using acrolein (CH2 = CHCHO) as a model alpha,beta-unsaturated carbonyl, we purified a predominant NADPH-dependent acrolein-reducing enzyme from cucumber leaves, and we identified the enzyme as an alkenal/one oxidoreductase (AOR) catalyzing reduction of an alpha,beta-unsaturated bond. Cloning of cDNA encoding AORs revealed that cucumber contains two distinct AORs, chloroplastic AOR and cytosolic AOR. Homologs of cucumber AORs were found among various plant species, including Arabidopsis, and we confirmed that a homolog of Arabidopsis (At1g23740) also had AOR activity. Phylogenetic analysis showed that these AORs belong to a novel class of AORs. They preferentially reduced alpha,beta-unsaturated ketones rather than alpha,beta-unsaturated aldehydes. Furthermore, we selected candidates of other classes of enzymes involved in NADPH-dependent reduction of carbonyls based on the bioinformatic information, and we found that an aldo-keto reductase (At2g37770) and aldehyde reductases (At1g54870 and At3g04000) were implicated in the reduction of an aldehyde group of saturated aldehydes and methylglyoxal as well as alpha,beta-unsaturated aldehydes in chloroplasts. These results suggest that different classes of NADPH-dependent reductases cooperatively contribute to the detoxification of reactive carbonyls.