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Evidence that the intra-amoebal Legionella drancourtii acquired a sterol reductase gene from eukaryotes.

Moliner C, Raoult D, Fournier PE - BMC Res Notes (2009)

Bottom Line: L. drancourtii acquired a sterol delta-7 reductase-encoding gene of viridiplantae origin.The most parsimonious hypothesis is that this gene was initially acquired by a Chlamydiales ancestor parasite of plants.The role of the sterol delta-7 reductase in prokaryotes is as yet unknown but we speculate that it is involved in host cholesterol parasitism.

View Article: PubMed Central - HTML - PubMed

Affiliation: URMITE CNRS-IRD UMR 6236, Faculté de Médecine, 27 boulevard Jean Moulin, 13385 Marseille, Cedex 05, France. claire.moliner@univmed.fr

ABSTRACT

Background: Free-living amoebae serve as a natural reservoir for some bacteria that have evolved into "amoeba-resistant" bacteria. Among these, some are strictly intra-amoebal, such as Candidatus "Protochlamydia amoebophila" (Candidatus "P. amoebophila"), whose genomic sequence is available. We sequenced the genome of Legionella drancourtii (L. drancourtii), another recently described intra-amoebal bacterium. By comparing these two genomes with those of their closely related species, we were able to study the genetic characteristics specific to their amoebal lifestyle.

Findings: We identified a sterol delta-7 reductase-encoding gene common to these two bacteria and absent in their relatives. This gene encodes an enzyme which catalyses the last step of cholesterol biosynthesis in eukaryotes, and is probably functional within L. drancourtii since it is transcribed. The phylogenetic analysis of this protein suggests that it was acquired horizontally by a few bacteria from viridiplantae. This gene was also found in the Acanthamoeba polyphaga Mimivirus genome, a virus that grows in amoebae and possesses the largest viral genome known to date.

Conclusion: L. drancourtii acquired a sterol delta-7 reductase-encoding gene of viridiplantae origin. The most parsimonious hypothesis is that this gene was initially acquired by a Chlamydiales ancestor parasite of plants. Subsequently, its descendents transmitted this gene in amoebae to other intra-amoebal microorganisms, including L. drancourtii and Coxiella burnetii. The role of the sterol delta-7 reductase in prokaryotes is as yet unknown but we speculate that it is involved in host cholesterol parasitism.

No MeSH data available.


Related in: MedlinePlus

PCR amplification and RT-PCR of the sterol delta-7 reductase-encoding gene. Lanes 1 and 6: DNA molecular weight marker VI (Roche); lanes 2 and 4: DNA; lanes 3 and 5: RNA
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Figure 2: PCR amplification and RT-PCR of the sterol delta-7 reductase-encoding gene. Lanes 1 and 6: DNA molecular weight marker VI (Roche); lanes 2 and 4: DNA; lanes 3 and 5: RNA

Mentions: RT-PCR from L. drancourtii RNA produced a sequence of the expected size (Figure 2). The sequence obtained from the RT-PCR product was identical to that of the 7-dehydrocholesterol reductase-encoding gene of L. drancourtii (Figure 3), confirming that it was transcribed. A control PCR performed on the RNA sample proved that there was no DNA contamination.


Evidence that the intra-amoebal Legionella drancourtii acquired a sterol reductase gene from eukaryotes.

Moliner C, Raoult D, Fournier PE - BMC Res Notes (2009)

PCR amplification and RT-PCR of the sterol delta-7 reductase-encoding gene. Lanes 1 and 6: DNA molecular weight marker VI (Roche); lanes 2 and 4: DNA; lanes 3 and 5: RNA
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2667531&req=5

Figure 2: PCR amplification and RT-PCR of the sterol delta-7 reductase-encoding gene. Lanes 1 and 6: DNA molecular weight marker VI (Roche); lanes 2 and 4: DNA; lanes 3 and 5: RNA
Mentions: RT-PCR from L. drancourtii RNA produced a sequence of the expected size (Figure 2). The sequence obtained from the RT-PCR product was identical to that of the 7-dehydrocholesterol reductase-encoding gene of L. drancourtii (Figure 3), confirming that it was transcribed. A control PCR performed on the RNA sample proved that there was no DNA contamination.

Bottom Line: L. drancourtii acquired a sterol delta-7 reductase-encoding gene of viridiplantae origin.The most parsimonious hypothesis is that this gene was initially acquired by a Chlamydiales ancestor parasite of plants.The role of the sterol delta-7 reductase in prokaryotes is as yet unknown but we speculate that it is involved in host cholesterol parasitism.

View Article: PubMed Central - HTML - PubMed

Affiliation: URMITE CNRS-IRD UMR 6236, Faculté de Médecine, 27 boulevard Jean Moulin, 13385 Marseille, Cedex 05, France. claire.moliner@univmed.fr

ABSTRACT

Background: Free-living amoebae serve as a natural reservoir for some bacteria that have evolved into "amoeba-resistant" bacteria. Among these, some are strictly intra-amoebal, such as Candidatus "Protochlamydia amoebophila" (Candidatus "P. amoebophila"), whose genomic sequence is available. We sequenced the genome of Legionella drancourtii (L. drancourtii), another recently described intra-amoebal bacterium. By comparing these two genomes with those of their closely related species, we were able to study the genetic characteristics specific to their amoebal lifestyle.

Findings: We identified a sterol delta-7 reductase-encoding gene common to these two bacteria and absent in their relatives. This gene encodes an enzyme which catalyses the last step of cholesterol biosynthesis in eukaryotes, and is probably functional within L. drancourtii since it is transcribed. The phylogenetic analysis of this protein suggests that it was acquired horizontally by a few bacteria from viridiplantae. This gene was also found in the Acanthamoeba polyphaga Mimivirus genome, a virus that grows in amoebae and possesses the largest viral genome known to date.

Conclusion: L. drancourtii acquired a sterol delta-7 reductase-encoding gene of viridiplantae origin. The most parsimonious hypothesis is that this gene was initially acquired by a Chlamydiales ancestor parasite of plants. Subsequently, its descendents transmitted this gene in amoebae to other intra-amoebal microorganisms, including L. drancourtii and Coxiella burnetii. The role of the sterol delta-7 reductase in prokaryotes is as yet unknown but we speculate that it is involved in host cholesterol parasitism.

No MeSH data available.


Related in: MedlinePlus