CRISPR system acquisition and evolution of an obligate intracellular chlamydia-related bacterium

Claire Bertelli, Ousmane H. Cissé, Brigida Rusconi, Carole Kebbi-Beghdadi, Antony Croxatto, Alexander Goesmann, François Collyn, Gilbert Greub

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Recently, a new Chlamydia-related organism, Protochlamydia naegleriophila KNic, was discovered within a Naegleria amoeba. To decipher the mechanisms at play in the modeling of genomes from the Protochlamydia genus, we sequenced the full genome of Pr. naegleriophila, which includes a 2,885,090 bp chromosome and a 145,285 bp megaplasmid. For the first time within the Chlamydiales order, we describe the presence of a clustered regularly interspaced short palindromic repeats (CRISPR) system, the immune system of bacteria, located on the chromosome. It is composed of a small CRISPR locus comprising eight repeats and associated cas-cse genes of the subtype I-E. A CRISPR locus is also present within Chlamydia sp. Diamant, another Pr. naegleriophila strain, suggesting that the CRISPR system was acquired by a common ancestor of Pr. naegleriophila, after its divergence from Pr. amoebophila. Both nucleotide bias and comparative genomics approaches identified probable horizontal gene acquisitions within two and four genomic islands in Pr. naegleriophila KNic and Diamant genomes, respectively. The plasmid encodes an F-type conjugative system highly similar to 1) that found in the Pam100G genomic island of Pr. amoebophila UWE25 chromosome, as well as on the plasmid of Rubidus massiliensis and 2) to the three genes remaining in the chromosome of Parachlamydia acanthamoebae strains. Therefore, this conjugative system was likely acquired on an ancestral plasmid before the divergence of Parachlamydiaceae. Overall, this new complete Pr. naegleriophila genome sequence enables further investigation of the dynamic processes shaping the genomes of the family Parachlamydiaceae and the genus Protochlamydia.

Original languageEnglish
Pages (from-to)2376-2386
Number of pages11
JournalGenome Biology and Evolution
Issue number8
StatePublished - Aug 2016


  • Chlamydiales
  • Comparative genomics
  • Genomic island
  • Plasmid
  • T4SS


Dive into the research topics of 'CRISPR system acquisition and evolution of an obligate intracellular chlamydia-related bacterium'. Together they form a unique fingerprint.

Cite this