Membrane Engine (Accelerator)
As there is no compartment in prokaryotic cells, enzymes involved in a biochemical pathway diffuse all over the cytoplasm. Intermediates generated from one enzyme cannot be passed efficiently to the next due to spatial obstacles. However, if we attach those enzymes to engineered membrane proteins which assemble together, the reactions are going to proceed much faster.
Why do we attach enzymes to interacting protein domains and ligands that assemble together?
- Interacting proteins fused with enzymes can decrease the distance which intermediates must travel between enzymes, improving reaction speed.
Why do we localize the enzymes to the membrane?
- Interaction of proteins can only be effective within a small distance. Membrane localization of the enzymes can integrate those engineered proteins to 2-dimensional scale, which would absolutely increase the possibility that potential interacting domains and ligands dimerize.
Membrane Switch
Now that we have built a device that can speed up a biological pathway. Our next goal is to control the pathway better---- to switch the direction of certain reactions, as shown in figure 3.
Divergent biochemical pathways commonly exist in all types of organisms, and most of those reactions are stringently and internally controlled. However, it is extremely hard to artificially control and switch the directions of these reactions. Usually there are two different products produced in divergent reactions. Sometimes we want one product, and sometimes we want the other. Using our designed device, we can change the direction by introducing different extracellular signals.
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