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Mechanism of metabolic puncta formation and its functional significance

The intracellular environment is very crowding and differs dramatically from the in vitro conditions under which studies of enzyme activity are typically performed.

Yuan Lin Research Image

Many metabolic enzymes have recently been shown to assemble into multi-component puncta in cells, and this assembly is though to play some role in controlling metabolic flux. For example, substrate channeling within these structures could play an important role in metabolism, enabling intermediates to be directly fed from one enzyme to another without dilution. Therefore the assembly of enzymes into these puncta could be an important mechanism for cells to manipulate their metabolism in response to different signals. However, the mechanism of formation of these puncta is completely unknown.

The ‘purinosome’ is a cellular structure formed by several proteins involved in de novo purine biosynthesis that forms in cells grown in purine-depleted conditions. I have found that some purinosome components can also form dynamic puncta in response to cellular stress. These structures behave like phase separated liquid droplets in the cytoplasm and are different from commonly known protein aggregates.

I am trying to uncover the mechanism of the formation of this new structure and its functional significance.