Intracellular Bacteria in the Blue-Green Alga Pleurocapsa minor

Wujek, Daniel E.

doi:10.2307/3225953

Cited by 44 publications

(25 citation statements)

References 8 publications

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“…For decades, traditional models have focused on phagocytosis and predation as the central, overarching and decisive evolutionary achievement in the prokaryoteto-eukaryote transition (Cavalier-Smith 1975, while overlooking the circumstance that the predatory lifestyle has indeed evolved on many different occasions among the prokaryotes, and each time it has brought forth highly effective predatory prokaryotic forms that invade, not engulf, their prey (Davidov & Jurkevitch 2009). One reason that phagocytosis was seen by some as so absolutely essential to the eukaryotic condition was based on the argument that without phagocytosis, it would not be possible for a prokaryote to take up residence within another cell (Cavalier-Smith 2002), but that argument is deflated by clear examples of prokaryotes living within other prokaryotes (Wujek 1979;von Dohlen et al 2001).…”

Section: What Pre-existing Cell Compartments Did the Host For The Orimentioning

confidence: 99%

Evolutionary origins of metabolic compartmentalization in eukaryotes

Martin

2010

Phil. Trans. R. Soc. B

186

136

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Many genes in eukaryotes are acquisitions from the free-living antecedents of chloroplasts and mitochondria. But there is no evolutionary 'homing device' that automatically directs the protein product of a transferred gene back to the organelle of its provenance. Instead, the products of genes acquired from endosymbionts can explore all targeting possibilities within the cell. They often replace pre-existing host genes, or even whole pathways. But the transfer of an enzymatic pathway from one compartment to another poses severe problems: over evolutionary time, the enzymes of the pathway acquire their targeting signals for the new compartment individually, not in unison. Until the whole pathway is established in the new compartment, newly routed individual enzymes are useless, and their genes will be lost through mutation. Here it is suggested that pathways attain novel compartmentation variants via a 'minor mistargeting' mechanism. If protein targeting in eukaryotic cells possesses enough imperfection such that small amounts of entire pathways continuously enter novel compartments, selectable units of biochemical function would exist in new compartments, and the genes could become selected. Dual-targeting of proteins is indeed very common within eukaryotic cells, suggesting that targeting variation required for this minor mistargeting mechanism to operate exists in nature.

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Section: What Pre-existing Cell Compartments Did the Host For The Orimentioning

confidence: 99%

Evolutionary origins of metabolic compartmentalization in eukaryotes

Martin

2010

Phil. Trans. R. Soc. B

186

136

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“…Gene transfer from organelles sets eukaryotes apart from prokaryotes, which in contrast to eukaryotes lack organelles descended from free-living prokaryotes. That is not to say that no prokaryotes harbour prokaryotic endosymbionts, for there are two such examples known (Wujek 1979 (Dolezal et al 2006) and secondary plastids (Hempel et al 2007), in which case it would qualify as an organelle, or not, in which case it is best called an endosymbiont (Theissen & Martin 2006).…”

Section: Including Eukaryotes In the Networkmentioning

confidence: 99%

Getting a better picture of microbial evolution en route to a network of genomes

Dagan

Martin

2009

Phil. Trans. R. Soc. B

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Most current thinking about evolution is couched in the concept of trees. The notion of a tree with recursively bifurcating branches representing recurrent divergence events is a plausible metaphor to describe the evolution of multicellular organisms like vertebrates or land plants. But if we try to force the tree metaphor onto the whole of the evolutionary process, things go badly awry, because the more closely we inspect microbial genomes through the looking glass of gene and genome sequence comparisons, the smaller the amount of the data that fits the concept of a bifurcating tree becomes. That is mainly because among microbes, endosymbiosis and lateral gene transfer are important, two mechanisms of natural variation that differ from the kind of natural variation that Darwin had in mind. For such reasons, when it comes to discussing the relationships among all living things, that is, including the microbes and all of their genes rather than just one or a select few, many biologists are now beginning to talk about networks rather than trees in the context of evolutionary relationships among microbial chromosomes. But talk is not enough. If we were to actually construct networks instead of trees to describe the evolutionary process, what would they look like? Here we consider endosymbiosis and an example of a network of genomes involving 181 sequenced prokaryotes and how that squares off with some ideas about early cell evolution.

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“…These are bacteria living inside a bacterial cell ( Figure 5). This is the only example that we know of, of bacteria inside a free-living bacterial cell 15 . There's plenty of bacteria inside eukaryotic cells which are large and complex and often engulf cells like bacteria for a living; but bacteria don't do that.…”

Section: Molecular Frontiers Journalmentioning

confidence: 98%

Origin of the Eukaryotic Cell

Lane¹

2017

Mol. Front. J.

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All complex life on Earth is composed of ‘eukaryotic’ cells. Eukaryotes arose just once in 4 billion years, via an endosymbiosis — bacteria entered a simple host cell, evolving into mitochondria, the ‘powerhouses’ of complex cells. Mitochondria lost most of their genes, retaining only those needed for respiration, giving eukaryotes ‘multi-bacterial’ power without the costs of maintaining thousands of complete bacterial genomes. These energy savings supported a substantial expansion in nuclear genome size, and far more protein synthesis from each gene.

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Intracellular Bacteria in the Blue-Green Alga Pleurocapsa minor

Cited by 44 publications

References 8 publications

Evolutionary origins of metabolic compartmentalization in eukaryotes

Evolutionary origins of metabolic compartmentalization in eukaryotes

Getting a better picture of microbial evolution en route to a network of genomes

Origin of the Eukaryotic Cell

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