NAD malic enzyme and the control of carbohydrate metabolism in potato tubers
NAD malic enzyme and the control of carbohydrate metabolism in potato tubers
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DOI：
10.1104/pp.126.3.1139
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发表时间：
2001-07-01
期刊：
影响因子：
7.4
通讯作者：
Hill, SA
中科院分区：
文献类型：
--
作者：
Jenner, HL;Winning, BM;Hill, SA
用编码马铃薯块茎NAD依赖性苹果酸酶（NADME）的59-kD亚基的cDNA以反义方向转化马铃薯（Solanum tuberosum）植物。NADME在块茎中的最大催化活性的测量揭示了这种酶的活性降低到野生型活性的40%的范围。对植物生长或块茎产量没有不利影响。发展块茎的生化分析表明，NADME活性的减少，通过三羧酸循环的流量没有检测到的影响。然而，糖酵解代谢的3-磷酸甘油酸和磷酸烯醇丙酮酸的浓度显着增加的影响。这些结果表明，糖酵解途径结束时中间产物水平的改变可能使呼吸流量继续以野生型速率，尽管NADME减少。NADME活性和块茎淀粉含量之间也存在统计学上显著的负相关关系，NADME活性降低的块茎淀粉含量增加。对质体代谢的影响可能是由于观察到的糖酵解扰动。
Potato (Solanum tuberosum) plants were transformed with a cDNA encoding the 59-kD subunit of the potato tuber NAD-dependent malic enzyme (NADME) in the antisense orientation. Measurements of the maximum catalytic activity of NADME in tubers revealed a range of reductions in the activity of this enzyme down to 40% of wild-type activity. There were no detrimental effects on plant growth or tuber yield. Biochemical analyses of developing tubers indicated that a reduction in NADME activity had no detectable effects on flux through the tricarboxylic acid cycle. However, there was an effect on glycolytic metabolism with significant increases in the concentration of 3-phosphoglycerate and phosphoenolpyruvate. These results suggest that alterations in the levels of intermediates toward the end of the glycolytic pathway may allow respiratory flux to continue at wild-type rates despite the reduction in NADME. There was also a statistically significant negative correlation between NADME activity and tuber starch content, with tubers containing reduced NADME having an increased starch content. The effect on plastid metabolism may result from the observed glycolytic perturbations.