Robertson D, Davies D R, Gerrish C, Jupe S C, Bolwell G P
Department of Biochemistry, Royal Holloway and Bedford New College, University of London, Egham, Surrey, UK.
Plant Mol Biol. 1995 Jan;27(1):59-67. doi: 10.1007/BF00019178.
Stressed plant cells often show increased oxygen uptake which can manifest itself in the transient production of active oxygen species, the oxidative burst. There is a lack of information on the redox status of cells during the early stages of biotic stress. In this paper we measure oxygen uptake and the levels of redox intermediates NAD/NADH and ATP and show the transient induction of the marker enzyme for redox stress, alcohol dehydrogenase. Rapid changes in the redox potential of elicitor-treated suspension cultures of French bean cells indicate that, paradoxically, during the period of maximum oxygen uptake the levels of ATP and the NADH/NAD ratio fall in a way that indicates the occurrence of stress in oxidative metabolism. This period coincides with the maximum production of active oxygen species particularly H2O2. The cells recover and start producing ATP immediately of H2O2 production. This indicates that the increased O2 uptake is primarily incorporated into active O2 species. A second consequence of these changes is probably a transient compromising of the respiratory status of the cells as indicated in expression of alcohol dehydrogenase. Elicitor-induced bean ADH was purified to homogeneity and the M(r) 40,000 polypeptide was subjected to amino acid sequencing. 15% of the whole protein was sequenced from three peptides and was found to have nearly 100% sequence similarity to the amino acid sequence for pea ADH1 (PSADH1). The cDNA coding for the pea enzyme was used to demonstrate the transient induction of ADH mRNA in elicitor-treated bean cells. Enzyme activity levels also increased transiently subsequently. Increased oxygen uptake has previously been thought to be associated with provision of energy for the changes in biosynthesis that occur rapidly after perception of the stress signal. However the present work shows that this rapid increase in oxygen uptake as a consequence of elicitor action is not wholly associated with respiration.
受到胁迫的植物细胞通常表现出氧气吸收增加，这可能表现为活性氧的短暂产生，即氧化爆发。关于生物胁迫早期细胞的氧化还原状态，目前缺乏相关信息。在本文中，我们测量了氧气吸收以及氧化还原中间体NAD/NADH和ATP的水平，并展示了氧化还原应激标记酶乙醇脱氢酶的短暂诱导。菜豆细胞激发子处理的悬浮培养物的氧化还原电位快速变化表明，矛盾的是，在氧气吸收最大的时期，ATP水平和NADH/NAD比值下降，这表明氧化代谢中发生了应激。这个时期与活性氧特别是H2O2的最大产生期相吻合。细胞恢复并在H2O2产生后立即开始产生ATP。这表明增加的O2吸收主要被整合到活性O2物种中。这些变化的第二个后果可能是细胞呼吸状态的短暂受损，如乙醇脱氢酶的表达所示。激发子诱导的菜豆ADH被纯化至同质，对40,000 Mr的多肽进行了氨基酸测序。从三个肽段对整个蛋白质的15%进行了测序，发现其与豌豆ADH1（PSADH1）的氨基酸序列具有近100%的序列相似性。编码豌豆酶的cDNA被用于证明激发子处理的菜豆细胞中ADH mRNA的短暂诱导。酶活性水平随后也短暂增加。先前认为增加的氧气吸收与为应激信号感知后迅速发生的生物合成变化提供能量有关。然而，目前的研究表明，由于激发子作用导致氧气吸收的这种快速增加并不完全与呼吸作用相关。
