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The origin of the eukaryotic cell
1Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada.
Trends in Biochemical Sciences
|May 1, 1996
Summary
The origin of eukaryotic cells likely involved an endosymbiotic event where a Gram-negative bacterium engulfed an archaebacterium. This fusion led to the chimera-like nucleus and endoplasmic reticulum, crucial for early cell evolution.
Area of Science:
- Evolutionary biology
- Molecular biology
- Cell biology
Background:
- Molecular sequence data offers insights into eukaryotic cell origins.
- Phylogenetic analyses suggest the eukaryotic nucleus is a chimera with contributions from eubacteria and archaebacteria.
Purpose of the Study:
- To investigate the evolutionary origin of eukaryotic cells using molecular sequence data.
- To elucidate the symbiotic event leading to the formation of the ancestral eukaryotic cell.
Main Methods:
- Global phylogenies of numerous protein sequences were analyzed.
- Gene duplication patterns of molecular chaperone proteins were examined.
Main Results:
- Phylogenetic data indicate a chimeric origin for the eukaryotic nucleus, with significant eubacterial and archaebacterial contributions.
- Gene duplication of molecular chaperones (hsp70, hsp90) coincided with nuclear envelope and endoplasmic reticulum formation.
Conclusions:
- The ancestral eukaryotic cell likely originated from an endosymbiotic event.
- A Gram-negative eubacterium engulfed an eocyte archaebacterium, forming the foundational eukaryotic cell.