Non-consecutive enzyme interactions within TCA cycle supramolecular assembly regulate carbon-nitrogen metabolism

• Published in: Nature communications Vol. 15; no. 1; pp. 5285 - 15
• Main Authors: Jasinska, Weronika, Dindo, Mirco, Cordoba, Sandra M. C., Serohijos, Adrian W. R., Laurino, Paola, Brotman, Yariv, Bershtein, Shimon
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 20.06.2024; Nature Publishing Group UK; Nature Portfolio
• Subjects: Ammonium; Carbon; Chemical reactions; Clustering; Dehydrogenase; Dehydrogenases; Diffusion rate; Enzymes; Isocitrate dehydrogenase; Ketoglutaric acid; Malate dehydrogenase; Metabolic flux; Metabolism; Nitrogen; Nitrogen metabolism; Reaction products; Tricarboxylic acid cycle
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-49646-7

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.