| Protomitocondria |
| --- |
|  |
| Clasificación científica |
| 

|  |  |
| --- | --- |
| Dominio: | Bacteria |
| Filo: | Pseudomonadota |
| Clase: | Alphaproteobacteria |
| Orde: | *Rickettsiales* (?) |

 |

A **protomitocondria** é o hipotético endosimbionte bacteriano ancestral a partir do cal se pensa que descenden todas as mitocondrias dos eucariotas, despois dun episodio de simbioxénese que creou a capacidade de realizar a respiración celular aerobia nas células eucariotas.

Filoxenia
---------

As análises filoxenéticas dos poucos xenes que aínda están codificados polo xenoma das modernas mitocondrias suxiren unha orixe alfaproteobacteriana para este endosimbionte, nun antigo episodio de simbioxénese na historia evolutiva dos eucariotas. Aínda que se propuxo a orde *Rickettsiales* como grupo irmán alfaproteobacteriano das mitocondrias, non hai probas definitivas en canto cal foi o grupo de alfaproteobacterias a partir do cal xurdiron as mitocondrias. Martijn *et al* atoparon que as mitocondrias son un posible grupo irmán de todas as outras alfaproteobacterias. Ferla et al. inferiron a árbore filoxenética das Rickettsidae comparando as secuencias de ARNr 16S + ARNr 23S.


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| Alphaproteobacteria | 

|  |  |
| --- | --- |
| Magnetococcidae | *Magnetococcus marinus* |
|   |
|   | 

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Caulobacteridae | 

|  |  |
| --- | --- |
|   | Rhodospirillales, Sphingomonadales,  Rhodobacteraceae, Hyphomicrobiales etc. |
|   |
|   | Holosporales |
|   |

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|   |
| Rickettsidae | 

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Pelagibacterales | 

|  |  |
| --- | --- |
| Pelagibacteraceae | *Pelagibacter* |
|   |
|   | Subgrupos Ib, II, IIIa, IIIb, IV e V |
|   |

 |
|   |
| Rickettsiales | 

|  |  |
| --- | --- |
|   | Proto-mitochondria |
|   |
|   | 

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Anaplasmataceae | 

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   | 

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|   | 

|  |  |
| --- | --- |
|   | *Ehrlichia* |
|   |
|   | *Anaplasma* |
|   |

 |
|   |
|   | *Wolbachia* |
|   |

 |
|   |
|   | *Neorickettsia* |
|   |

 |
|   |
|   | 

|  |  |
| --- | --- |
| Midichloriaceae | *Midichloria* |
|   |
| Rickettsiaceae | 

|  |  |
| --- | --- |
|   | *Rickettsia* |
|   |
|   | *Orientia* |
|   |

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|   |

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|   |

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|   |

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|   |

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|   |

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|   |

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|   |

Metabolismo
-----------

Toni Gabaldón e Martijn Huynen (2003) reconstruíron o proteoma (o conxunto completo de proteínas expresado por un xenoma) e o metabolismo correspondente da protomitocondria comparando os xenomas existentes de alfaproteobacterias e eucariotas. Concluíron que este organismo era unha alfaproteobacteria aerobia que respiraba lípidos, glicerol e outros compostos proporcionados polo hóspede. Polo menos 630 familias de xenes derivadas deste organismo poden aínda atoparse nos 9 xenomas eucariotas analizados no estudo.

Notas
-----

1. ↑  Martijn, Joran; Vosseberg, Julian; Guy, Lionel; Offre, Pierre; Ettema, Thijs J. G. (2018). "Deep mitochondrial origin outside the sampled alphaproteobacteria". *Nature* **557** (7703): 101–105. Bibcode:2018Natur.557..101M. ISSN 0028-0836. PMID 29695865. doi:10.1038/s41586-018-0059-5.
2. ↑  Ferla, Mattep P.; Thrash, J. Cameron; Giovannoni, Stephen J.; Patrick, Wayne M. (2013). "New rRNA gene-based phylogenies of the Alphaproteobacteria provide perspective on major groups, mitochondrial ancestry and phylogenetic instability". *PLOS ONE* **8** (12): e83383. Bibcode:2013PLoSO...883383F. PMC 3859672. PMID 24349502. doi:10.1371/journal.pone.0083383.
3. ↑  Gabaldón, Toni; Huynen, Martijn A. (2003). "The proto-mitochondrial metabolism". *Science* **301** (5633): 690. PMID 12893934. doi:10.1126/science.1085463.

Véxase tamén
------------

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* Abioxénese
* Simbioxénese
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* Midichloria
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