CHARACTERIZATION AND EXPRESSION OF A NADP-MALIC ENZYME CDNA INDUCED BY SALT STRESS FROM THE FACULTATIVE CRASSULACEAN ACID METABOLISM PLANT, MESEMBRYANTHEMUM-CRYSTALLINUM
CHARACTERIZATION AND EXPRESSION OF A NADP-MALIC ENZYME CDNA INDUCED BY SALT STRESS FROM THE FACULTATIVE CRASSULACEAN ACID METABOLISM PLANT, MESEMBRYANTHEMUM-CRYSTALLINUM
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DOI：
10.1111/j.1432-1033.1992.tb17181.x
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发表时间：
1992-09-01
期刊：
影响因子：
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通讯作者：
CUSHMAN, JC
中科院分区：
文献类型：
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作者：
CUSHMAN, JC
中胚草是兼性盐生植物和景天科酸代谢植物，在高盐或干旱条件下，其C3光合作用转变为景天科酸代谢。为了研究这种代谢转变的分子基础，研究了NADP+依赖性苹果酸酶（NADP-ME）的表达，该酶催化苹果酸脱羧以释放丙酮酸和CO2。测定了一个全长cDNA克隆的核苷酸序列，发现它含有一个单一的开放阅读框，编码一个585个氨基酸的多肽，分子量为64284 Da。当与其它高等植物酶相比时，NADP-ME共享72.5 - 79.0%范围内的氨基酸同一性，并且与酶的C3而不是C4形式更密切相关。对冰草基因组DNA的Southern杂交分析表明，NADP-ME由一个小基因家族编码。稳态转录水平增加8 - 10倍，响应于盐胁迫的叶片。根中的转录水平极低，不受盐胁迫处理的影响。核运行的实验，使用分离的细胞核从叶组织，证实NADP-ME成绩单的积累是，在一定程度上，盐胁迫过程中，该基因的转录增加的结果。
The facultative halophyte and crassulacean acid-metabolism plant, Mesembryanthemum crystallinum shifts from C3 photosynthesis to crassulacean acid metabolism when exposed to high-salt or drought conditions. To study the molecular basis of this metabolic transition, the expression of NADP+-dependent malic enzyme (NADP-ME), which catalyzes the decarboxylation of malate to release pyruvate and CO2, has been investigated. The complete nucleotide sequence of a full-length cDNA clone was determined and found to contain a single open reading frame encoding a 585-amino-acid polypeptide of 64284 Da. The ice plant (M. crystallinum) NADP-ME shares amino acid identities in the range 72.5 - 79.0% when compared to other higher-plant enzymes and is more closely related to C3 rather than C4 forms of the enzyme. Genomic Southern-blot analysis of ice-plant DNA indicates that NADP-ME is encoded by a small gene family. Steady-state transcript levels increase 8 - 10-fold in response to salt stress in the leaves. Transcript levels in roots are extremely low and are unaffected by salt-stress treatment. Nuclear run-on experiments, using isolated nuclei from leaf tissue, confirm that the accumulation of NADP-ME transcripts is, in part, the result of increased transcription of this gene during salt stress.