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BP: Fachverband Biologische Physik

BP 49: Physics of the Genesis of Life - Focus Session organized by Moritz Kreysing and Dieter Braun

BP 49.9: Vortrag

Donnerstag, 23. März 2017, 12:00–12:15, SCH A251

Origin of a folded repeat protein from an intrinsically disordered ancestor — •Hongbo Zhu, Edgardo Sepulveda, Marcus D Hartmann, Manjunatha Kogenaru, Reinhard Albrecht, Jörg Martin, and Andrei N Lupas — Max Planck Institute for Developmental Biology, Tuebingen, Germany

Life today depends entirely on proteins as catalysts, but this activity is dependent on the formation of defined three-dimensional structures (folding). As only few randomly synthesized polypeptide chains have a folded structure, folding was clearly a major obstacle in the evolution of DNA-protein-based lifeforms from simpler precursor forms. We have proposed that folded proteins resulted from the increasing complexity of a preselected, ancestral set of peptides, which supported RNA-based life and required the RNA to assume their active conformation. A dominant mechanism to increase complexity is repetition and we have attempted to recreate experimentally the path from an unstructured precursor to a folded protein by amplification. Specifically we used a fragment of the putatively ancient ribosomal protein S20 (RPS20), which is only structured in the context of the ribosomal RNA, to generate a wide-spread fold in living organisms today, the TPR fold. After computational optimization of the fragment, we obtained a native-like TPR fold with 2-5 point mutations, which were neutral in the parent organism, suggesting that they could have been sampled in the course of evolution. TPRs could thus have plausibly arisen by amplification from an ancestral peptide.