The cytoplasmic structure hypothesis for ribosome assembly, vertical inheritance, and phylogeny

Area of Science:

• Evolutionary biology
• Molecular biology
• Synthetic biology

Background:

• Fundamental evolutionary questions involve life's divisions and gene transfer mechanisms.
• Two models exist: three superkingdoms (Archaea, Eubacteria, Eukarya) via vertical inheritance, or a prokaryotic/eukaryotic split with extensive horizontal gene transfer (HGT) in prokaryotes.
• Vertical inheritance preserves cellular information, while HGT primarily transfers DNA.

Purpose of the Study:

• To propose a hypothesis explaining constraints on HGT of the translation machinery.
• To suggest experimental approaches using synthetic biology to test these constraints.

Main Methods:

• The study is primarily theoretical, proposing a hypothesis based on existing knowledge of gene transfer and ribosome function.
• It suggests experiments for synthetic biology to validate the proposed mechanism.

Main Results:

• Hypothesizes that HGT of ribosomal genes is constrained by interactions between new ribosomal proteins and existing cytoplasmic structures (ribosomes).
• Proposes that ribosomes selectively enhance the assembly of homologous ribosomal proteins and inhibit non-homologous ones.
• Predicts that synthetic genomes' ability to establish hereditary continuity ('boot') will depend on the phylogenetic relatedness to the host cell's existing machinery.

Conclusions:

• Ribosome-mediated interactions act as a constraint on horizontal gene transfer, particularly for essential machinery like the translation apparatus.
• This constraint has implications for understanding the evolution of life's major divisions.
• Synthetic biology offers a powerful tool to experimentally investigate these evolutionary mechanisms.