Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany.
Center of Plant System Biology and Biotechnology, 4000, Plovdiv, Bulgaria.
Plant J. 2023 Jun;114(5):1080-1092. doi: 10.1111/tpj.16179. Epub 2023 Apr 8.
Metabolons are temporary structural-functional complexes of sequential enzymes of a metabolic pathway that are distinct from stable multi-enzyme complexes. Here we provide a brief history of the study of enzyme-enzyme assemblies with a particular focus on those that mediate substrate channeling in plants. Large numbers of protein complexes have been proposed for both primary and secondary metabolic pathways in plants. However, to date only four substrate channels have been demonstrated. We provide an overview of current knowledge concerning these four metabolons and explain the methodologies that are currently being applied to unravel their functions. Although the assembly of metabolons has been documented to arise through diverse mechanisms, the physical interaction within the characterized plant metabolons all appear to be driven by interaction with structural elements of the cell. We therefore pose the question as to what methodologies could be brought to bear to enhance our knowledge of plant metabolons that assemble via different mechanisms? In addressing this question, we review recent findings in non-plant systems concerning liquid droplet phase separation and enzyme chemotaxis and propose strategies via which such metabolons could be identified in plants. We additionally discuss the possibilities that could be opened up by novel approaches based on: (i) subcellular-level mass spectral imaging, (ii) proteomics, and (iii) emergent methods in structural and computational biology.
代谢物是代谢途径中顺序酶的临时结构功能复合物，与稳定的多酶复合物不同。在这里，我们简要回顾了酶-酶组装的研究历史，特别关注那些在植物中介导底物通道化的组装。已经为植物的初级和次级代谢途径提出了大量的蛋白质复合物。然而，迄今为止，仅证实了四个底物通道。我们概述了目前关于这四个代谢物的知识，并解释了目前用于揭示其功能的方法。尽管已经证明代谢物的组装是通过多种机制产生的，但在已鉴定的植物代谢物中，其内部的物理相互作用似乎都是由与细胞结构元素的相互作用驱动的。因此，我们提出了一个问题，即可以采用哪些方法来增强我们对通过不同机制组装的植物代谢物的了解？在解决这个问题时，我们回顾了关于非植物系统中液滴相分离和酶化学趋化性的最新发现，并提出了通过这些方法可以在植物中鉴定代谢物的策略。我们还讨论了基于以下新方法可能带来的可能性：（i）亚细胞水平的质谱成像，（ii）蛋白质组学，以及（iii）结构和计算生物学中的新兴方法。
