A bioarchitectonic approach to the modular engineering of metabolism.

Dissociating the complexity of metabolic processes into modules is a shift in focus from the single gene/gene product to functional and evolutionary units spanning the scale of biological organization. When viewing the levels of biological organization through this conceptual lens, modules are found across the continuum: domains within proteins, co-regulated groups of functionally associated genes, operons, metabolic pathways and (sub)cellular compartments. Combining modules as components or subsystems of a larger system typically leads to increased complexity and the emergence of new functions. By virtue of their potential for 'plug and play' into new contexts, modules can be viewed as units of both evolution and engineering. Through consideration of lessons learned from recent efforts to install new metabolic modules into cells and the emerging understanding of the structure, function and assembly of protein-based organelles, bacterial microcompartments, a structural bioengineering approach is described: one that builds from an architectural vocabulary of protein domains. This bioarchitectonic approach to engineering cellular metabolism can be applied to microbial cell factories, used in the programming of members of synthetic microbial communities or used to attain additional levels of metabolic organization in eukaryotic cells for increasing primary productivity and as the foundation of a green economy.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'.