Data/hora: 13/06/2024 01:20:37

Provedor de dados: | 5
País: | France
Título: | Découverte et caractérisation des premiers virus de Thermotogales (bactéries thermophiles et anaérobies) issus de sources hydrothermales océaniques profondes
Autores: | Loussouarn, Julien.
Data: | 2014-03-21
Ano: | 2014
Palavras-chave: | Sources hydrothermales océaniques profondes; Siphovirus; Plasmides; Piratage moléculaire; Plasmids; Molecular piracy; Deep sea hydrothermal vents; Thermotogales; Siphoviruses.
Resumo: | Our knowledge of the viral diversity associated to procaryotic microorganisms inhabiting the deep sea hydrothermal vents is still limited. Only few studies have focused on viral abundance and impact on microbial mortality within these ecosystems. A limited number of viruses from these environments were isolated and characterized. Two viruses, PAV1 and TPV1, associated to hyperthermophilic anaerobic Archaea, Thermococcales order, have ever been described in our laboratory. The topic of this phD thesis was to extend our investigation to other deep sea vent microorganisms in order to deepen our knowledge on the marine hydrothermal virosphere. We decided to focus more precisely on the bacterial order of Thermotogales. This order is composed of anaerobic chemoorganotrophic bacteria that are, for almost, hyper/thermophilic. They share the same ecological niche as the Thermococcales and are metabolically close. Numerous lateral gene transfers have contributed to the evolutionary history of the Thermotogales, implying the potential involvement of viruses. The presence of CRISPRs has also been reported in many genomes, suggesting that Thermotogales certainly are or have been exposed to viral infections. However, up till now, only 3 miniplasmids have been described within Thermotogales and no viruses.  Fifty strains of Thermotogales, mostly from the LM2E culture collection (Ifremer and “UBOCC”), were screened for the presence of potential bacteriovirus.  Extrachromosomal DNA elements, including two plasmids and seven bacterioviruses (Siphovirus-like), were discovered amongst strains belonging to both Thermosipho and Marinitoga genus. Preliminary studies were performed on these elements and one of the new virus-host systems was characterized in details. MPV1 (Marinitoga piezophila virus 1) is a temperate Siphovirus-like isolated from a piezophilic bacterium, it is the first bacteriovirus associated to the Thermotogales order. This host strain is piezophilic but easily cultivable at atmospheric pressure after several subcultures. Whether most experiments were performed at atmospheric pressure, the viral production appeared to be effective at hydrostatic pressure.  We reported the analyses of the complete sequence of the MPV1 genome (43.7 kb, extracted from purified virions) and its comparison to the provirus present in the sequenced genome of Marinitoga piezophila KA3. Analyses of the viral genome suggested a close evolutionary relationship of MPV1 to Firmicutes bacterioviruses .We also reported that this bacteriovirus shares its host with a circular extrachromosomal genetic element of 13.3 kb (pMP1). This ‘ménage à trois’ is surprising in the sense where the 13kb element, that contains 13 ORFs of mostly unknown function, uses the viral capsid to propagate. Therefore, it would likely correspond to a new example of molecular piracy.
Tipo: | Text
Idioma: | Francês

Identificador:

https://archimer.ifremer.fr/doc/00609/72137/70889.pdf

https://archimer.ifremer.fr/doc/00609/72137/

Editor: | Université de Bretagne Occidentale
Formato: | application/pdf

Fonte:

info:eu-repo/semantics/openAccess

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