Glyceraldehyde-3-phosphate dehydrogenase subunits A and B are essential to maintain photosynthetic efficiency
Glyceraldehyde-3-phosphate dehydrogenase subunits A and B are essential to maintain photosynthetic efficiency
复制标题
3-磷酸甘油醛脱氢酶亚基 A 和 B 对于维持光合作用效率至关重要
DOI：
10.1093/plphys/kiad256
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发表时间：
2023
期刊：
影响因子：
7.4
通讯作者：
Simkin A
中科院分区：
文献类型：
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作者：
Simkin A
在植物中，3-磷酸甘油醛脱氢酶(GAPDH；EC 1.2.1.12)可逆地将1，3-二磷酸甘油酸转化为3-磷酸甘油醛，同时将NADPH还原为NADP+。在Calvin-Benson循环中发挥作用的GAPDH酶是由4个甘油醛-3-磷酸脱氢酶A(GAPA)亚单位蛋白组成同源四聚体(A4)或由2个GAPA和2个甘油醛-3-磷酸脱氢酶B(GAPB)亚单位蛋白组成异四聚体(A2B2)。这两种形式的GAPDH在决定光合作用速率方面的相对重要性尚不清楚。为了解决这个问题，我们利用GAPA和GAPB的T-DNA插入系以及低水平的GAPA和GAPB转基因植株，分别和联合测量了含有减少的GAPDHA和B亚基的拟南芥(Arabiopsis Thaliana)植株的光合作用速率。在这里，我们表明，降低A或B亚基的水平会降低二氧化碳固定的最大效率、植物生长和最终生物量。最后，这些数据表明，GAPA蛋白降低到野生型水平的9%导致碳同化率下降73%。相反，去除GAPB蛋白会导致同化率降低40%。这项工作表明，GAPA同源四聚体可以补偿GAPB的损失，而单独的GAPB不能完全补偿GAPA亚单位的损失。
In plants, glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12) reversibly converts 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate coupled with the reduction of NADPH to NADP+. The GAPDH enzyme that functions in the Calvin–Benson cycle is assembled either from 4 glyceraldehyde-3-phosphate dehydrogenase A (GAPA) subunit proteins forming a homotetramer (A4) or from 2 GAPA and 2 glyceraldehyde-3-phosphate dehydrogenase B (GAPB) subunit proteins forming a heterotetramer (A2B2). The relative importance of these 2 forms of GAPDH in determining the rate of photosynthesis is unknown. To address this question, we measured the photosynthetic rates ofArabidopsis(Arabidopsis thaliana) plants containing reduced amounts of the GAPDH A and B subunits individually and jointly, using T-DNA insertion lines of GAPA and GAPB and transgenic GAPA and GAPB plants with reduced levels of these proteins. Here, we show that decreasing the levels of either the A or B subunits decreased the maximum efficiency of CO2fixation, plant growth, and final biomass. Finally, these data showed that the reduction in GAPA protein to 9% wild-type levels resulted in a 73% decrease in carbon assimilation rates. In contrast, eliminating GAPB protein resulted in a 40% reduction in assimilation rates. This work demonstrates that the GAPA homotetramer can compensate for the loss of GAPB, whereas GAPB alone cannot compensate fully for the loss of the GAPA subunit.