水稻OsALDH7基因的功能初步分析
首发时间:2011-01-13
摘要:ALDH7在动植物中高度保守,人类中的ALDH7A1基因参与赖氨酸降解途径中α-氨基己二酸半醛(AASA)的氧化过程。植物ALDH7在豌豆,油菜,苹果,藓类,高粱和拟南芥等物种中已得到克隆,它们的表达与果实的成熟和植物所受的渗透压逆境相关,但其具体作用还待进一步研究。实验室以一个黄色胚乳的天然突变体为材料定位和克隆了OsALDH7基因,本研究初步探讨了该基因的功能。检测赖氨酸代谢途径中的相关基因(LOR/SDH,AK,DHPS)的表达和代谢产物(各种氨基酸、酵母氨酸等)的含量,发现OsALDH7基因的突变造成水稻中赖氨酸降解加剧及其代谢产物酵母氨酸的积累;而在酵母中过表达OsALDH7,可以使得酵母游离赖氨酸含量大幅下降,而赖氨酸的代谢产物-酵母氨酸及其谷氨酸含量上升。综合上述实验结果,推测OsALDH7很可能参与水稻中赖氨酸的降解途径,水稻中缺失正常功能的OsALDH7后,赖氨酸可能通过未知的支路途径转化成色素物质。进一步实验确认发现色素物质的主要成分为水稻突变体酸A,发现其受生育期和储存时间延长而加剧积累。
关键词: 功能分析 乙醛脱氢酶七 赖氨酸代谢 水稻 水稻突变体酸A
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Preliminary research on the function of OsALDH7 in rice (Oryza sativa L.)
Abstract:The family ALDH7 is highly conserved in whatever animals or plants. ALDH7A1, ALDH7 homolog in human, catalyzes the oxidation of α-amino adipic semialdehyde (AASA) in lysine degradation. As yet, the expressions of ALDH7 in plants such as garden pea, brassica, apple, tortula ruralis, sorghum and Arabidopsis were found to be associated with seed maturation and osmotic stress, but their exact functions were still remain to be clarified. Using a natural mutant with yellow endosperm, we isolated and cloned OsALDH7, and the function was further analyzed. The expression of related gene (LOR/SDH, AK, DHPS) and the contents of intermediate compounds (amino acids, saccharopine, et al.) in lysine metabolism were detected in W3660 (Wildtype) and jmw (Mutant), and we found the mutation of OsALDH7 induced the accumulation of saccharopine but the degradation of lysine. Moreover, the over-expressing of OsALDH7 in yeast could cause great decease of lysine and an increase of glutamate, which is the product of lysine degradation. OsALDH7 in rice probably participate in the degradation of lysine, and without normal OsALDH7, lysine might be transformed to the pigment through some unknown processes. We also identified the main component of the pigment was oryzamutaic acid A, which could be more seriously accumulated along with seed ripen or aging.
Keywords: Gene function analysis Aldehyde Dehydrogenase7 Lysine Metabolism Rice (Oryza sativa L.) Oryzamutaic Acid A
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