Origin and evolution of eukaryotic compartmentalization
The origin of eukaryotic compartmentalization stands as a major conundrum in biology. Current evidence indicates that the last eukaryotic common ancestor (LECA) already possessed many eukaryotic hallmarks, including a complex subcellular organization. The lack of evolutionary intermediates challenge...
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| Formato: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Recursos: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/397755 |
| Acesso em linha: | http://hdl.handle.net/10803/397755 |
| Access Level: | acceso abierto |
| Palavra-chave: | Evolution Eukaryotes Organelles Endosymbiosis Evolución Eucariotas Orgánulos Endosimbiosis 576 |
| Resumo: | The origin of eukaryotic compartmentalization stands as a major conundrum in biology. Current evidence indicates that the last eukaryotic common ancestor (LECA) already possessed many eukaryotic hallmarks, including a complex subcellular organization. The lack of evolutionary intermediates challenges the elucidation of the relative order of emergence of eukaryotic traits. Central in the discussion is the exogenous origin of mitochondria, ubiquitous eukaryotic organelles derived from an α-proteobacterial endosymbiont. Different hypotheses disagree on whether mitochondria were acquired early or late during eukaryogenesis. Similarly, the nature and complexity of the receiving host are debated, with models ranging from a simple prokaryotic host to an already complex proto-eukaryote. In this thesis, I have used phylogenomic methods to address different questions on the origin and evolution of subcellular compartmentalization in Eukaryotes. We provide evidence for extensive retargeting of proteins between the different compartments, and suggest an evolutionary link between mitochondria and peroxisomes. We focus on the evolution of calcium homeostasis in mitochondria and reveal strong co-evolution patterns among the components of the recently identified mitochondrial calcium uniporter complex. Through alternative methodologies we analyze the phylogenetic signal carried by LECA-inferred gene families. Our analyses indicate that the ancestral eukaryotic proteome is a composite of genes originating from different prokaryotic sources. Finally, our work provides strong support for the late acquisition of mitochondria by a complex host. Altogether, our findings shed light on long-standing questions on the origin of Eukaryotes and provide new grounds for further advancements, as new data become available. |
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