The emergence of major cellular processes in evolution

Area of Science:

• Evolutionary biology
• Genomics
• Biochemistry

Background:

• Phylogenetic distribution of protein families across archaea, bacteria, and eukaryotes reveals cellular process evolution.
• Understanding the evolutionary status of archaea and the origin of eukaryotic cells remains a key challenge.

Purpose of the Study:

• To reconstruct the cellular processes present in the last universal ancestor (LUA).
• To test hypotheses regarding the evolutionary relationship between archaea and the LUA.
• To predict evolutionary trajectories based on genomic data.

Main Methods:

• Phylogenetic analysis of protein families across the three domains of life.
• Linking protein families to biochemical pathways to infer ancestral processes.
• Utilizing presence/absence of protein families as taxonomic traits.

Main Results:

• The LUA possessed complex metabolism, including amino acid, nucleotide, fatty acid, sugar, and coenzyme metabolism.
• Translation is highly conserved and similar to its primordial form.
• DNA replication, repair, and transcription show significant divergence, linked to the evolution of eukaryotes and bacteria.

Conclusions:

• Archaea are likely closer to the LUA than other extant life forms.
• Major cellular processes, including metabolism and translation, were established before the major evolutionary split.
• The LUA had an operonic genome organization and archaean-like transcription, with evidence persisting in modern cells.