Changes of the lipid catabolism in potato tubers from cultivars differing in susceptibility to autolysis during the storage

Summary The activities of lipolytic acyl-hydrolases (LAH) and lipoxygenases (LOX) were compared in stored tubers of potato cultivars resistant (Acresta, Eba, Pentland Envoy) and susceptible (Kastor, Pana, Tasso) to post-wounding autolysis. In most cultivars, LAH activities had reached a maximum by the end of December but in cv. Kastor activity continued to increase throughout the storage period. LOX activities increased during most of the storage period except in cv. Tasso. The level of the fatty acid hydroperoxides, assumed from determinations of the malonaldehyde level, also increased during storage. This work was supported by Project CPBP 05.02.2.10 financed by the Polish Academy of Science.     

Role of LOX3 Gene in Alleviating Adverse Effects of Drought and Pathogens in Rice

Lipoxygenase 3 (LOX3) is a major component of the LOX isozymes in mature rice seeds. To investigate the role of LOX3 gene under stresses, a plant expression vector containing antisense cDNA of LOX3 was constructed. Rice varieties Wuyunjing 7 and Kasalath were transformed by the Agrobacterium-mediated method and transgenic rice plants were generated. PCR and Southern blot results showed that the antisense LOX3 gene was integrated into the rice genome. Analyses of embryo LOX3 deletion and semi-quantitative RT-PCR confirmed the antisense suppression of LOX3 gene in transgenic plants. The T2 antisense plants of LOX3 were sensitive to drought stress, rice blast and bacterial blight compared with non-transgenic plants. These results suggest that the LOX3 gene might function in response to stresses.     

Prokaryotic Expression, Purification and Characterization of a Novel Rice Seed Lipoxygenase Gene OsLOX1

Lipoxygenase (LOX, EC1.13.11.12) is a key enzyme during the degradation of lipids in animals and even plants, and also the first key enzyme responsible for the biosynthesis of jasmonate. To purify and characterize the OsLOX1 gene from rice seeds, the entire coding region of the OsLOX1 gene was inserted into an expression vector pET30a(+) and transformed into Escherichia coli BL21 (DE3). Expression of the fusion protein was successfully induced by isopropyl-β-D- thiogalactopyranoside (IPTG) and the purified ...     

基于EST库的猕猴桃脂氧合酶基因家族成员的克隆

利用猕猴桃EST库及相关生物信息学手段, 从果肉组织克隆了LOX基因家族成员6个, 命名为AdLox1-6。AdLox1、AdLox2、AdLox3和AdLox4 为全长cDNA, 编码区长度分别为2 739、2 595、2 739 和 2 709 bp, AdLox5和AdLox6为cDNA片段, 长度为1 359和1 557 bp。猕猴桃AdLox2和AdLox5氨基酸序列同源性最高, 约74%, 而AdLox3 和AdLox5 仅为49%。生物信息学分析表明, AdLox1、AdLox3、AdLox4 和 AdLox6可能具有132LOX活性, 在N端含有额外约60个氨基酸残基, 而AdLox2和AdLox5则属于92LOX类型。猕猴AdLox1与番茄TomLoxD具有最高氨基酸序列同源性(约80%) , AdLox2和AdLox5与TomLoxA高度聚类, 序列同源性分别为68%和75%, AdLox4和AdLox6与TomLoxC的氨基酸序列同源性分别为62%和63%, AdLox3与番茄LOX基因序列同源性低于55%。     

脂氧合酶对唐菖蒲籽球形成和膨大的影响

为探讨脂氧合酶(LOX-1)对唐菖蒲籽球形成和膨大的影响,以'Rose Supreme'和'Advanced Red'两个品种为试材,研究了籽球的生长发育与LOX-1活性,内源茉梨酸甲酯(MJ)、蔗糖、淀粉和纤维素含量变化之间的关系。结果表明,唐菖蒲叶片中测不到LOX-1活性,匍匐茎中LOX-1活性和内源MJ含量最高,籽球数量较多的品种'Rose Supreme'LOX-1活性和MJ含量显著高于'Advanced Red',说明LOX-1在唐菖蒲籽球形成和膨大过程中起着重要作用,其作用途径可能是通过影响茉莉酸类化合物(JAs)的生物合成对籽球的发生和生长进行调控。在唐菖蒲籽球生长发育过程中,新球和籽球中蔗糖、淀粉和纤维素含量都不同程度升高,并且与LOX-1活性呈正相关,说明蔗糖、淀粉和纤维素对唐菖蒲新球和籽球的形成和膨大起着重要作用。     

水稻种子脂氧合酶基因OsLOX1的原核表达、纯化及鉴定

脂氧合酶是动植物体内催化脂质降解的关键酶,也是茉莉酸合成途径的第一个关键酶。以先前克隆到的水稻种子脂氧合酶基因OsLOX1全长cDNA为模板,用含有特异酶切位点的P1、P2为引物,通过PCR方法将它构建到大肠杆菌表达载体pET30a(+)上并转化到大肠杆菌菌株BL21（DE3）中,获得相应的重组工程菌。经过20℃条件下的IPTG诱导,OsLOX1重组蛋白在BL21（DE3）菌株中得到表达,经生化特性分析,发现该重组蛋白具有LOX催化活性,其最适pH和温度分别为4.8和30℃。该重组子可进一步应用于体外生产茉莉酸和研究植物种子LOX结构与功能的关系。     

大豆脂氧酶的热失活动力学与其二级结构的圆二色谱表现

应用大豆脂氧酶的变温圆二色谱图研究了大豆脂氧酶(LOX)的热失活与二级结构变化过程.结果表明:在50一65℃条件下,10 min内,LOX的酶活随热处理时间延长而下降,其热失活过程遵循一级动力学,活化能Ea值为217 kJ.mol-1.在相同的热处理条件下,LOX中二级结构a-螺旋和β-折叠的相对含量均在20%左右浮动...     

乳突果脂氧合酶基因的原核表达及酶活性测定

脂氧合酶(LOX)是植物十八碳酸途径中一个很重要的酶,该酶作用的产物在植物的生长发育过程中以及在植物对环境胁迫反应中起着重要的作用.通过PCR和酶切连接的方法,构建了乳突果脂氧合酶基因的原核表达载体,将其导入大肠杆菌BL21(DE3)中,在低温(15℃)条件下,表达出了有活性的酶蛋白,且该蛋白分子量与预期分子量相符.通过LC-ESI-MS检测,该酶可催化亚油酸生成9,10,11-三羟基-12-十八碳烯酸.推测在乳突果中,几丁质诱导的十八碳酸代谢途径是沿着9-LOX方向进行的.     

玉米大斑病菌毒素对玉米叶肉细胞脂氧合酶活性的影响

 玉米大斑病菌2号小种粗毒素(HT-C)和标准毒素(5-羟甲基-2-呋喃甲醛,HT-I)处理玉米叶片,都能诱导3种供试基因型玉米叶片中脂氧合酶活性增高,但是不同基因型玉米对HT-C和HT-I的反应不同,HT-I对含有Ht1基因的品系诱导时间早,水平高,HT-C对于不带Ht基因的品系LOX的影响略高于HT-I;不同浓度的HT-I在OH43和OH43Ht1玉米叶片中诱导的LOX酶活性不同,高浓度HT-I和HT-C对LOX酶活诱导时间早,水平高,浓度降低诱导水平降低;外源H₂O₂对HT-I和HT-C在OH43叶片中LOX酶活性诱导作用的影响不同。