Dynamic organization of glycolytic routes and the Calvin-Benson-Bassham cycle during the autotrophy-heterotrophy switch

在蓝细菌集胞藻PCC 6803的中心碳水化合物代谢中，以相反方向操作的过程高度交织。以分解代谢方向代谢碳水化合物的糖酵解途径与Calvin-Benson-Bassham（CBB）循环共享几种酶和反应，CBB循环以合成代谢方式运作。这些相反的过程在空间上没有分离，因为蓝细菌是没有任何进一步区室化的原核生物。由于CO2通过CBB循环的固定是由光中的光合作用驱动的，而糖酵解途径对于黑暗中碳水化合物的分解代谢利用是重要的，因此在光与暗之间的自养异养切换期间，这两个过程在时间上是分开的。然而，与我们的合作伙伴Forchhammer和Wittmann一起，我们可以证明糖酵解途径在自养条件下也很重要。它们在过渡状态下形成分流，补充和微调CBB循环。为此，内部糖原库被用作碳水化合物来源。Enter-Doudoroff（艾德）途径和氧化戊糖磷酸（PETP）途径的关键酶参与这些分流，而Emden-Meyerhoff-Parnas（EMP）途径不参与。我们计划进一步研究糖酵解途径和CBB循环的微调，特别是研究这些过程是否在细胞的空间水平上显示出动态组织。除此之外，与我们的合作伙伴Hagemann和Forchhammer一起，缺失艾德途径的突变体（Δeda）的生理学表征揭示了与野生型（WT）相比的几个表型差异。这些发现与通量分析部分矛盾。因此，我们计划检查观察到的Δeda表型是否完全依赖于Eda的缺失，或者在突变体的构建过程中是否有其他调控单位（例如非编码RNA）被沉默，这可能是观察到的与WT的差异的原因。此外，我们想检查埃达是否可能有月光功能或可能参与动态过程的微调中央碳水化合物代谢

Processes that operate in opposite directions are highly intertwined in the central carbohydrate metabolism of the cyanobacterium Synechocystis sp. PCC 6803. Glycolytic routes, that metabolize carbohydrates in catabolic direction, share several enzymes and reactions with the Calvin-Benson-Bassham (CBB) cycle, which operates anabolically. These opposing processes are not separated spatially, as cyanobacteria are prokaryotes without any further compartmentation. As the fixation of CO2 via the CBB cycle is driven by photosynthesis in the light, whereas glycolytic routes are of importance for the catabolic utilization of carbohydrates in darkness, both processes are separated time-wise during the autotrophy heterotrophy switch between light and darkness. However, together with our cooperation partners Forchhammer and Wittmann, we could show that glycolytic routes are as well of importance under autotrophic conditions. They form shunts in transition states that replenish and fine-tune the CBB cycle. For this, internal glycogen reservoirs are utilized as carbohydrate sources. Key enzymes of the Enter-Doudoroff (ED) pathway and the oxidative pentose phosphat (OPP) pathway participate in these shunts whereas the Emden-Meyerhoff-Parnas (EMP) pathway is not involved. We plan to investigate the fine-tuning of glycolytic routes und the CBB cycle further and to examine particularly, if these processes show a dynamic organization on a spatial level in the cells. Apart from that, the physiologic characterization of a mutant (Δeda) with deleted ED pathway together with our cooperation partners Hagemann and Forchhammer revealed several phenotypic differences in comparison to the wild type (WT). These findings are partly contradictory to flux analyses. We therefore plan to check, if the observed phenotypes of Δeda rely exclusively on the deletion of Eda, or whether other regulatory units as e.g. noncoding RNAs were silenced during the construction of the mutant which might be responsible for the observed differences to the WT. In addition, we want to check if Eda might have moonlight functions or might participate in dynamic processes for the fine-tuning of the central carbohydrate metabolism