First principles design of a core bioenergetic transmembrane electron-transfer protein

• Single chain man-designed transmembrane protein binds active tetrapyrrole chain.
• Heme and light-active tetrapyrrole assembly resembles ancestral photosynthetic proteins.
• Maquette platform reveals transmembrane oxidoreductase construction engineering.

Here we describe the design, Escherichia coli expression and characterization of a simplified, adaptable and functionally transparent single chain 4-α-helix transmembrane protein frame that binds multiple heme and light activatable porphyrins. Such man-made cofactor-binding oxidoreductases, designed from first principles with minimal reference to natural protein sequences, are known as maquettes. This design is an adaptable frame aiming to uncover core engineering principles governing bioenergetic transmembrane electron-transfer function and recapitulate protein archetypes proposed to represent the origins of photosynthesis. This article is part of a Special Issue entitled Biodesign for Bioenergetics — the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson.