Important News: Communicative & Integrative Biology will be indexed at PubMed Central!

Email this page

Print this page

Opinion Article

Origin of eukaryotes as a symbiosis of parasitic α-proteobacteria in the periplasm of two-membrane-bounded sexual prekaryotes

Matej Vesteg and Juraj Krajčovič

This is an open-access article

 Download PDF

If the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.

The last universal common ancestor (LUCA) might have been either prokaryotic- or eukaryotic-like. Nevertheless, the universally distributed components suggest rather LUCA consistent with the pre-cell theory of Kandler. The hypotheses for the origin of eukaryotes are briefly summarized. The models under which prokaryotes or their chimeras were direct ancestors of eukaryotes are criticized. It is proposed that the pre-karyote (a host entity for α-proteobacteria) was a remnant of pre-cellular world, and was unlucky to have evolved fusion prohibiting cell surface, and thus could have evolved sex. The DNA damage checkpoint pathway could have represented the only pre-karyotic checkpoint control allowing division only when DNA was completely replicated without mistakes. The fusion of two partially diploid (in S-phase blocked) pre-karyotes might have represented another repair strategy. After completing replication of both haploid sets, DNA damage checkpoint would allow two subsequent rounds of fission. Alternatively, pre-karyote might have possessed two membranes inherited from LUCA. Under this hypothesis symbiotic α-proteobacterial ancestors of mitochondria might have ancestrally been selfish parasites of pre-karyote intermembrane space whose infection might have been analogous to infection of G--bacterial periplasm by Bdellovibrio sp. It is suggested that eukaryotic plasma membrane might be derived from pre-karyote outer membrane and nuclear/ER membrane might be derived from pre-karyote inner membrane. Thus the nucleoplasm might be derived from pre-karyote cytoplasm and eukaryotic cytoplasm might be homologous to pre-karyote periplasm.

Authors

Matej Vesteg

Comenius University, Institute of Cell Biology

Juraj Krajčovič

Comenius University, Institute of Cell Biology

This is an open-access article

 Download PDF

If the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.