Predation between prokaryotes and the origin of eukaryotes

Abstract

Accumulating data suggest that the eukaryotic cell originated from a merger of two prokaryotes, an archaeal host and a bacterial endosymbiont. However, since prokaryotes are unable to perform phagocytosis, the means by which the endosymbiont entered its host is an enigma. We suggest that a predatory or parasitic interaction between prokaryotes provides a reasonable explanation for this conundrum. According to the model presented here, the host in this interaction was an anaerobic archaeon with a periplasm-like space. The predator was a small (facultative) aerobic alpha-proteobacterium, which penetrated and replicated within the host periplasm, and later became the mitochondria. Plausible conditions under which this interaction took place and circumstances that may have led to the contemporary complex eukaryotic cell are discussed.

Bdellovibrio and Like Organisms

“…Reduction in disease severity and systemic symptoms was significant. BALOs can also be employed as theoretical models for understanding the evolution of the eukaryotic cell (Davidov and Jurkevitch 2009;Guerrero et al 1986); they also are convenient empirical models for testing hypotheses pertaining to ecological and evolutionary theories (Gallet et al 2007(Gallet et al , 2009Wilkinson 2007).…”

Amoeba/Amoebal Symbiont Genetic Transfers: Lessons from Giant Virus Neighbours

“…and insects and nematodes hosts [88] . (16) Wolbachia bacteriophages are widespread, present high recombination rates and can be laterally transferred between different Wolbachia species [89] .…”

“…The most plausible primary endosymbiotic event was invasion of a prokaryote related to archaebacteria by another prokaryote related to alpha-proteobacteria and presenting Bdellovibrio -like bacteriovory ability, leading to the formation of mitochondria and to the first primitive eukaryotic cells [15][16][17] . It has been proposed that a phage also took part in the establishment of mitochondria in addition to the alpha-proteobacteria, since several mitochondrial genes involved in replication and transcription are related to the T-odd lineage of bacteriophages [18] .…”

Eukaryotic Origins: How and When Was the Mitochondrion Acquired?

“…Likewise, Midichloria mitochondrii, an a-proteobacterial endosymbiont of tick mitochondria (Sassera et al 2006;Montagna et al 2013), could be accounted for by this mechanism. However, although the case has been made for bacteriovory at the origin of the eukaryote cell (Davidov and Jurkevitch 2009), this mechanism fails to explain eukaryote origins for the simple reason that there are no documented instances of a bacterial predator invading archaeal cells, so it does not fit the criterion of cross-domain interaction nor crossdomain endosymbiosis (Table 1). This absence of archaeal prey is notable not only for cytoplasmic or periplasmic cell entry, but also applies to other known mechanisms of bacteriovory such as wolf pack predation by Myxococcus and epibiontic attachment by Vampirococcus (Martin 2002).…”