Malic Enzyme, not Malate Dehydrogenase, Mainly Oxidizes Malate That Originates from the Tricarboxylic Acid Cycle in Cyanobacteria.
Malic Enzyme, not Malate Dehydrogenase, Mainly Oxidizes Malate That Originates from the Tricarboxylic Acid Cycle in Cyanobacteria.
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作者：
光合自养细菌，蓝藻，具有三羧酸（TCA）循环，和代谢产物的生产使用蓝藻TCA循环最近已受到关注。单细胞蓝细菌集胞藻属菌株PCC 6803（集胞藻属6803）已用于蓝细菌TCA循环的各种研究。TCA循环中的苹果酸氧化通常由苹果酸脱氢酶（MDH）催化。然而，集胞藻6803 MDH（SyMDH）的活性低于其他生物体的MDH。此外，SyMDH仅使用NAD+作为辅酶，这与集胞藻6803中使用NADP+的其他TCA循环酶不同。这些结果表明，MDH很少催化苹果酸氧化的蓝藻TCA循环。另一种催化苹果酸氧化的酶是苹果酸酶（ME）。我们澄清了酶氧化苹果酸，源于蓝藻TCA循环使用集中在ME和MDH的分析。与SyMDH相反，当NADP+用作辅酶时，集胞藻6803 ME（SyME）显示出高活性。与缺乏SyMDH的集胞藻6803突变体不同，缺乏SyME的突变体在细胞中积累苹果酸。ME比MDH在蓝藻基因组中的保存程度更高。这些结果表明，ME主要是氧化苹果酸，起源于蓝藻TCA循环（命名为ME依赖TCA循环）。ME依赖性TCA循环产生NADPH，而不是NADH。这与以前的报道一致，NADPH是蓝藻呼吸链中的电子载体。我们的研究结果表明，在生物体中的TCA循环中涉及的酶的多样性，和分析，如在本研究中进行的是必要的，以确定酶。
Oxygenic photoautotrophic bacteria, cyanobacteria, have the tricarboxylic acid (TCA) cycle, and metabolite production using the cyanobacterial TCA cycle has been spotlighted recently. The unicellular cyanobacterium Synechocystis sp. strain PCC 6803 (Synechocystis 6803) has been used in various studies on the cyanobacterial TCA cycle. Malate oxidation in the TCA cycle is generally catalyzed by malate dehydrogenase (MDH). However, Synechocystis 6803 MDH (SyMDH) is less active than MDHs from other organisms. Additionally, SyMDH uses only NAD+ as a coenzyme, unlike other TCA cycle enzymes from Synechocystis 6803 that use NADP+. These results suggest that MDH rarely catalyzes malate oxidation in the cyanobacterial TCA cycle. Another enzyme catalyzing malate oxidation is malic enzyme (ME). We clarified which enzyme oxidizes malate that originates from the cyanobacterial TCA cycle using analyses focusing on ME and MDH. In contrast to SyMDH, Synechocystis 6803 ME (SyME) showed high activity when NADP+ was used as a coenzyme. Unlike the Synechocystis 6803 mutant lacking SyMDH, the mutant lacking SyME accumulated malate in the cells. ME was more highly preserved in the cyanobacterial genomes than MDH. These results indicate that ME mainly oxidizes malate that originates from the cyanobacterial TCA cycle (named the ME-dependent TCA cycle). The ME-dependent TCA cycle generates NADPH, not NADH. This is consistent with previous reports that NADPH is an electron carrier in the cyanobacterial respiratory chain. Our finding suggests the diversity of enzymes involved in the TCA cycle in the organisms, and analyses such as those performed in this study are necessary to determine the enzymes.
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影响因子：
5.2
作者：
Brandenburg F;Theodosiou E;Bertelmann C;Grund M;Klähn S;Schmid A;Krömer JO
通讯作者：
Krömer JO
DOI：
10.1074/jbc.ra120.016847
发表时间：
2021-01
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Nakamura S;Fu N;Kondo K;Wakabayashi KI;Hisabori T;Sugiura K
通讯作者：
Sugiura K
影响因子：
5.4
作者：
Gerrard Wheeler, Mariel C.;Arias, Cintia L.;Drincovich, Maria F.
通讯作者：
Drincovich, Maria F.
影响因子：
4.6
作者：
Nishii M;Ito S;Katayama N;Osanai T
通讯作者：
Osanai T
影响因子：
4.4
作者：
Kawai, S;Suzuki, H;Kumagai, H
通讯作者：
Kumagai, H