Synthetic Protein Scaffolding at Biological Membranes

Protein scaffolding techniques are increasingly being used to create synthetic protein complexes bound to biological membranes. Scaffolding tags can be used to recruit soluble enzymes or complexes to specific membrane domains. Synthetic transport metabolons, where enzymes are scaffolded to transmembrane transporters, are a powerful means to control metabolite fate upstream of central carbon metabolism. New membrane-integral scaffolding tools facilitate the design of synthetic complexes of membrane-requiring enzymes. Protein scaffolding is a natural phenomenon whereby proteins colocalize into macromolecular complexes via specific protein–protein interactions. In the case of metabolic enzymes, protein scaffolding drives metabolic flux through specific pathways by colocalizing enzyme active sites. Synthetic protein scaffolding is increasingly used as a mechanism to improve product specificity and yields in metabolic engineering projects. To date, synthetic scaffolding has focused primarily on soluble enzyme systems, but many metabolic pathways for high-value secondary metabolites depend on membrane-bound enzymes. The compositional diversity of biological membranes and general challenges associated with modifying membrane proteins complicate scaffolding with membrane-requiring enzymes. Several recent studies have introduced new approaches to protein scaffolding at membrane surfaces, with notable success in improving product yields from specific metabolic pathways. Protein scaffolding is a natural phenomenon whereby proteins colocalize into macromolecular complexes via specific protein–protein interactions. In the case of metabolic enzymes, protein scaffolding drives metabolic flux through specific pathways by colocalizing enzyme active sites. Synthetic protein scaffolding is increasingly used as a mechanism to improve product specificity and yields in metabolic engineering projects. To date, synthetic scaffolding has focused primarily on soluble enzyme systems, but many metabolic pathways for high-value secondary metabolites depend on membrane-bound enzymes. The compositional diversity of biological membranes and general challenges associated with modifying membrane proteins complicate scaffolding with membrane-requiring enzymes. Several recent studies have introduced new approaches to protein scaffolding at membrane surfaces, with notable success in improving product yields from specific metabolic pathways. a protein comprising two or more domains from different proteins, genetically encoded by a single open reading frame. protein domains or short peptides that can be fused to a protein of interest, and which interact with other specific interaction tags, facilitating complex formation between proteins that are fused to complementary pairs of interaction tags. eukaryotic subcellular compartment with a hydrophobic core of neutral lipids enclosed by a phospholipid monolayer. Lipid droplets bud from the ER during lipogenesis. a high-molecular weight structure comprising multiple proteins that interact post translationally. relative rate at which a metabolite is processed through several catalytic steps. molecules produced by enzymes in a metabolic pathway that are precursors to the final product of the pathway. protein complex containing sequential enzymes of a metabolic pathway held together via noncovalent interactions. complex formed by a small set of monomers (e.g., between three and ten monomers) from a larger pool. Protein oligomers could comprise different or identical monomers. process where different proteins form a complex via specific protein–protein interactions, sometimes via intermediary structural proteins. structural protein that serves as an assembly hub for other proteins that bind to it via noncovalent interactions. process where a metabolic intermediate is directly transferred from one enzyme to the next without diffusing in the local environment continuous network of membranes inside the chloroplast that hosts the photosynthetic light reactions. Thylakoids have a bilayer membrane that separates the internal thylakoid lumen from the bulk aqueous phase of the chloroplast (the stroma).