Sprecher
Beschreibung
The idea that life can act as a guide to its own origins has gained in strength in recent years with experimental work demonstrating that a biomimetic protometabolism starting from H2 and CO2 is indeed favoured in the absence of genes and enzymes. I will present some of our own recent work, both modelling and experimental, which shows that (i) CO2 fixation can be driven by a pH gradient across Fe(Ni)S barriers; (ii) protocells composed of simple amphiphiles can be formed readily under these conditions and are stable across a wide pH range; (iii) FeS clusters with redox potentials in the range needed to reduce CO2 can form spontaneously in the presence of monomeric cysteine or short peptides; and (iv) protometabolic pathways catalysed by metal ions are capable of synthesising amino acids and nucleobases including uracil. Taken together, these findings suggest that protocells could feasibly grow autotrophically by CO2 fixation via the acetyl CoA pathway and reverse incomplete Krebs cycle. Modelling work indicates that positive feedbacks in autotrophic protocells could amplify flux through the system, facilitating nucleotide synthesis. I will end with some thoughts on the emergence of genetic information in autotrophically growing protocells.
