Cell-free system composed of interdependent metabolic (Cetch cycle, pink) and genetic (Pure, blue) levels that recursively interact with one another. Pure produces the missing enzymes for CO2 fixation (i.e. Epi and Ecm) by transcription and translation (TX-TL) of Epi and Ecm genes; Cetch utilizes such enzymes for synthesizing glycine from CO2, thus sustaining protein production. Enzyme abbreviations Epi, Ecm, and RNAP stand for methylmalonyl-/ethylmalonyl-CoA epimerase, ethylmalonyl-CoA mutase, ...