14:55 〜 15:15
[BBG01-05] Evolution from simple peptides toward RNA polymerase –Structural biology views on the origin of life–
★Invited Papers
キーワード：タンパク質、生命の起源、構造生物学
In modern living systems, most biochemical functions are carried out by proteins with specific sequences and complex structures. However, it is still unclear how such elaborate molecular machines emerged on the ancient earth. Of particular interest is how RNA polymerase, the central protein of our gene expression system, emerged and evolved into its current gigantic form (~0.4 MDa). To understand such an ancient evolutionary process, we have been trying to experimentally reconstruct the evolutionary pathway from primitive peptides to modern RNA polymerases.
Recently, we have demonstrated simple cationic-hydrophobic peptides (e.g., K2V6) can form insoluble aggregates containing amyloid structures, capture RNA molecules on their surfaces in a size-dependent manner, and thus enhance RNA polymerization by an artificial ribozyme. Such simple peptides might have helped the accumulation and evolution of RNA on the ancient earth (Peiying Li et al., bioRxiv, 2021).
Then, we also reconstructed the ancient beta-barrel conserved at the core of RNA polymerase by homodimerization of a 43 a.a. peptide with only seven amino acid types (A, D, E, G, K, R, and V). The seven amino acids are encoded on a clearly defined area in the standard codon table (GNN and ARR), suggesting the core fold of RNA polymerase could have been synthesized by a primitive translation system (Sota Yagi et al., JACS, 2021).
Interestingly, the two richest amino acid types in the reconstructed beta-barrel were valine and lysine, which were also used to form the amyloid structures that enhance RNA polymerization by RNA. These results suggest a possible evolutionary pathway from simple peptide co-factors of ancient ribozymes to the modern proteinaceous RNA polymerase. Implications of this study for biomolecular evolution in a more general context (on the earth and also on other planets) will also be discussed.
Recently, we have demonstrated simple cationic-hydrophobic peptides (e.g., K2V6) can form insoluble aggregates containing amyloid structures, capture RNA molecules on their surfaces in a size-dependent manner, and thus enhance RNA polymerization by an artificial ribozyme. Such simple peptides might have helped the accumulation and evolution of RNA on the ancient earth (Peiying Li et al., bioRxiv, 2021).
Then, we also reconstructed the ancient beta-barrel conserved at the core of RNA polymerase by homodimerization of a 43 a.a. peptide with only seven amino acid types (A, D, E, G, K, R, and V). The seven amino acids are encoded on a clearly defined area in the standard codon table (GNN and ARR), suggesting the core fold of RNA polymerase could have been synthesized by a primitive translation system (Sota Yagi et al., JACS, 2021).
Interestingly, the two richest amino acid types in the reconstructed beta-barrel were valine and lysine, which were also used to form the amyloid structures that enhance RNA polymerization by RNA. These results suggest a possible evolutionary pathway from simple peptide co-factors of ancient ribozymes to the modern proteinaceous RNA polymerase. Implications of this study for biomolecular evolution in a more general context (on the earth and also on other planets) will also be discussed.