One of the NAD kinases, sll1415, is required for the glucose metabolism of Synechocystis sp. PCC 6803
One of the NAD kinases, sll1415, is required for the glucose metabolism of Synechocystis sp. PCC 6803
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DOI：
10.1111/tpj.14262
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发表时间：
2019-05-01
期刊：
影响因子：
7.2
通讯作者：
Kawai-Yamada, Maki
中科院分区：
文献类型：
--
作者：
Ishikawa, Yuuma;Miyagi, Atsuko;Kawai-Yamada, Maki
吡啶核苷酸（NAD（P）（H））是电子载体，是各种代谢途径的驱动力。NAD（H）磷酸化为NADP（H）是由NAD激酶（NADK）进行的。集胞藻PCC 6803具有两个编码具有NADK同源性的蛋白质的基因（sll 1415和slr 0400）。当在光异养生长条件下培养sll 1415和slr 0400的遗传突变体（分别为Delta 1415和Delta 0400）时，仅Delta 1415细胞显示出生长缺陷。在野生型细胞中，sll 1415转录物在细胞转移到光异养条件后积累。此外，NAD（P）（H）的测量表明，在从光合自养到光合异养的适应过程中，实现了动态的代谢转换。电镜观察和生化定量结果表明，在光异养条件下培养96 h，Delta 1415细胞内糖原大量积累。定量实时逆转录PCR（qRT-PCR）证明了编码糖原生物合成相关酶的mRNA在光合异养Delta 1415细胞中的积累。在96 h时，光异养Delta 1415细胞中的酶活性测定表明，葡萄糖-6-磷酸脱氢酶和6-磷酸葡萄糖酸脱氢酶的活性降低，而葡萄糖脱氢酶的活性升高。代谢组学分析表明，在96 h时，Delta 1415细胞中葡萄糖-6-磷酸和6-磷酸葡萄糖酸含量增加。因此，sll 1415在光异养条件下葡萄糖的氧化戊糖磷酸（pentose phosphate，pentose phosphate）途径中具有重要的功能。此外，推测slr 0400在生长期间的葡萄糖催化中具有不同的作用。这些结果表明，两个集胞藻PCC 6803 NADK（Sll 1415和Slr 0400）在光合异养蓝藻代谢中具有不同的功能。
Pyridine nucleotides (NAD(P)(H)) are electron carriers that are the driving forces in various metabolic pathways. Phosphorylation of NAD(H) to NADP(H) is performed by the enzyme NAD kinase (NADK). Synechocystis sp. PCC 6803 harbors two genes (sll1415 and slr0400) that encode proteins with NADK homology. When genetic mutants for sll1415 and slr0400 (Delta 1415 and Delta 0400, respectively) were cultured under photoheterotrophic growth conditions only the Delta 1415 cells showed a growth defect. In wild-type cells, the sll1415 transcript accumulated after the cells were transferred to photoheterotrophic conditions. Furthermore, NAD(P)(H) measurements demonstrated that a dynamic metabolic conversion was implemented during the adaptation from photoautotrophic to photoheterotrophic conditions. Electron microscopy observation and biochemistry quantification demonstrated the accumulation of glycogen in the Delta 1415 cells under photoheterotrophic conditions at 96 h. Quantitative real-time reverse transcription PCR (qRT-PCR) demonstrated the accumulation of mRNAs that encoded glycogen biosynthesis-related enzymes in photoheterotrophic Delta 1415 cells. At 96 h, enzyme activity measurement in the photoheterotrophic Delta 1415 cells demonstrated that the activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were decreased, but the activities of glucose dehydrogenase were increased. Furthermore, metabolomics analysis demonstrated that the Delta 1415 cells showed increased glucose-6-phosphate and 6-phosphogluconate content at 96 h. Therefore, sll1415 has a significant function in the oxidative pentose phosphate (OPP) pathway for catabolism of glucose under photoheterotrophic conditions. Additionally, it is presumed that the slr0400 had a different role in glucose catabolism during growth. These results suggest that the two Synechocystis sp. PCC 6803 NADKs (Sll1415 and Slr0400) have distinct functions in photoheterotrophic cyanobacterial metabolism.