PDF(Pubmed)
Abstract：
Enzymes of the central metabolism tend to assemble into transient supramolecular complexes. However, the functional significance of the interactions, particularly between enzymes catalyzing non-consecutive reactions, remains unclear. Here, by co-localizing two non-consecutive enzymes of the TCA cycle from Bacillus subtilis, malate dehydrogenase (MDH) and isocitrate dehydrogenase (ICD), in phase separated droplets we show that MDH-ICD interaction leads to enzyme agglomeration with a concomitant enhancement of ICD catalytic rate and an apparent sequestration of its reaction product, 2-oxoglutarate. Theory demonstrates that MDH-mediated clustering of ICD molecules explains the observed phenomena. In vivo analyses reveal that MDH overexpression leads to accumulation of 2-oxoglutarate and reduction of fluxes flowing through both the catabolic and anabolic branches of the carbon-nitrogen intersection occupied by 2-oxoglutarate, resulting in impeded ammonium assimilation and reduced biomass production. Our findings suggest that the MDH-ICD interaction is an important coordinator of carbon-nitrogen metabolism.
摘要：
中心代谢的酶倾向于组装成瞬时的超分子复合物。然而,相互作用的功能意义，特别是在催化非连续反应的酶之间，尚不清楚。这里,通过共定位枯草芽孢杆菌TCA循环的两种非连续酶，苹果酸脱氢酶（MDH）和异柠檬酸脱氢酶（ICD），在相分离的液滴中，我们表明MDH-ICD相互作用导致酶凝聚，伴随着ICD催化速率的增强和其反应产物的明显螯合。2-氧戊二酸。理论证明MDH介导的ICD分子聚类解释了观察到的现象。体内分析表明，MDH过表达导致2-氧戊二酸的积累和流过2-氧戊二酸占据的碳氮交叉的分解代谢和合成代谢分支的通量减少，导致铵同化受阻，生物量产量减少。我们的发现表明，MDH-ICD相互作用是碳氮代谢的重要协调者。
