POSTTRANSCRIPTIONAL AND POSTTRANSLATIONAL CONTROL OF ENOLASE EXPRESSION IN THE FACULTATIVE CRASSULACEAN ACID METABOLISM PLANT MESEMBRYANTHEMUM-CRYSTALLINUM L
POSTTRANSCRIPTIONAL AND POSTTRANSLATIONAL CONTROL OF ENOLASE EXPRESSION IN THE FACULTATIVE CRASSULACEAN ACID METABOLISM PLANT MESEMBRYANTHEMUM-CRYSTALLINUM L
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DOI：
10.1104/pp.108.3.1185
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发表时间：
1995-07-01
期刊：
影响因子：
7.4
通讯作者：
CUSHMAN, JC
中科院分区：
文献类型：
--
作者：
FORSTHOEFEL, NR;CUSHMAN, MAF;CUSHMAN, JC
在普通冰植物（Mesembryanthemum crystinum L.）的糖酵解和糖异生过程中，包括烯醇酶（2-磷酸- d -甘油水解酶）在内的酶活性显著增加。在这项研究中，我们描述了两个几乎相同的cDNA克隆（Pgh1a和Pgh1b）编码烯醇化酶从普通冰植物。这种细胞质定位酶由至少两个成员的基因家族编码。这些cdna编码的多肽与其他高等植物烯醇酶具有高度的氨基酸序列一致性（86.7-88.3%）。盐胁迫下叶片烯醇化酶活性增加4倍以上。这种增加伴随着Pgh1转录率的急剧增加和烯醇化酶转录物在叶片中的积累。在低温、干旱和厌氧胁迫条件下，以及用植物生长调节剂脱落酸和6-苄基氨基嘌呤处理未受胁迫的植物时，叶片中Pgh1转录水平也有所增加。在根中，烯醇化酶转录物在盐、低温和高温以及厌氧胁迫下丰度增加。令人惊讶的是，我们没有观察到烯醇化酶蛋白水平的增加，尽管mRNA水平和酶活性在盐胁迫下增加。因此，应力诱导的烯醇化酶活性的增加是由于稳态酶池的翻译后调节。我们的研究结果表明，在冰植物中，应激诱导的向天冬氨酸代谢的转变涉及复杂的调控机制，这些机制在转录、转录后和翻译后水平上起作用。
During the induction of Crassulacean acid metabolism by environmental stresses in the common ice plant (Mesembryanthemum crystallinum L.), enzyme activities involved in glycolysis and gluconeogenesis, including enolase (2-phospho-D-glycerate hydrolase), increase significantly. In this study, we describe two nearly identical cDNA clones (Pgh1a and Pgh1b) encoding enolase from the common ice plant. This cytoplasmically localized enzyme is encoded by a gene family of at least two members. The polypeptides encoded by these cDNAs share a high degree of amino acid sequence identity (86.7-88.3%) with other higher plant enolases. Enolase activity increased more than 4-fold in leaves during salt stress. This increase was accompanied by a dramatic increase in Pgh1 transcription rate and the accumulation of enolase transcripts in leaves. Pgh1 transcript levels also increased in leaves in response to low temperature, drought, and anaerobic stress conditions and upon treatment of unstressed plants with the plant growth regulators abscisic acid and 6-benzylaminopurine. In roots, enolase transcripts increased in abundance in response to salt, low and high temperature, and anaerobic stresses. Surprisingly, we observed no increase in enolase protein levels, despite the increased levels of mRNA and enzyme activity during salt stress. The stress-induced increase in enolase activity is therefore due to posttranslational regulation of steady-state enzyme pools. Our results demonstrate that the stress-induced shift to Crassulacean acid metabolism in the ice plant involves complex regulatory control mechanisms that operate at the transcriptional, posttranscriptional, and posttranslational levels.