Cellular production of ade novomembrane cytochrome

Abstract

ABSTRACTHeme-containing integral membrane proteins are at the heart of many bioenergetic complexes and electron transport chains. The importance of these electron relay hubs across biology has inspired the design ofde novoproteins that recreate their core features within robust, versatile and tractable protein folds. To this end, we report here the computational design and in-cell production of a minimal diheme membrane cytochrome which successfully integrates into the cellular membrane of live bacteria. This synthetic construct emulates a four-helix bundle found in modern respiratory complexes but has no sequence homology to any polypeptide sequence found in nature. The twob-type hemes, which appear to be recruited from the endogenous heme pool, have distinct split redox potentials with values close to those of natural membrane-spanning cytochromes. The purified protein can engage in rapid biomimetic electron transport with small molecules, with other redox proteins, and with biologically-relevant diffusive electron carriers. We thus report an artificial membrane metalloprotein with the potential to serve as a functional module in electron transfer pathways in both synthetic protocells and living systems.