title: Genomic context drives transcription of insertion sequences in the bacterial endosymbiont Wolbachia wVulC.
abstract: Transposable elements (TEs) are DNA pieces that are present in almost all the living world at variable genomic density. Due to their mobility and density, TEs are involved in a large array of genomic modifications. In eukaryotes, TE expression has been studied in detail in several species. In prokaryotes, studies of IS expression are generally linked to particular copies that induce a modification of neighboring gene expression. Here we investigated global patterns of IS transcription in the Alphaproteobacterial endosymbiont Wolbachia wVulC, using both RT-PCR and bioinformatic analyses. We detected several transcriptional promoters in all IS groups. Nevertheless, only one of the potentially functional IS groups possesses a promoter located upstream of the transposase gene, that could lead up to the production of a functional protein. We found that the majority of IS groups are expressed whatever their functional status. RT-PCR analyses indicate that the transcription of two IS groups lacking internal promoters upstream of the transposase start codon may be driven by the genomic environment. We confirmed this observation with the transcription analysis of individual copies of one IS group. These results suggest that the genomic environment is important for IS expression and it could explain, at least partly, copy number variability of the various IS groups present in the wVulC genome and, more generally, in bacterial genomes.
authors: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpin, 86073 Poitiers Cedex 9, France.
authors: Nicolas
authors: N
authors: Cerveau
authors: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpin, 86073 Poitiers Cedex 9, France.
authors: Clément
authors: C
authors: Gilbert
authors: Department of Biology, University of Copenhagen, 2200N Copenhagen, Denmark.
authors: Chao
authors: C
authors: Liu
authors: Department of Biology, University of Copenhagen, 2200N Copenhagen, Denmark.
authors: Roger A
authors: RA
authors: Garrett
authors: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpin, 86073 Poitiers Cedex 9, France.
authors: Pierre
authors: P
authors: Grève
authors: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpin, 86073 Poitiers Cedex 9, France.
authors: Didier
authors: D
authors: Bouchon
authors: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpin, 86073 Poitiers Cedex 9, France. Electronic address: richard.cordaux@univ-poitiers.fr.
authors: Richard
authors: R
authors: Cordaux
mesh_terms: D000818:Animals; D004251:DNA Transposable Elements; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D033321:Isopoda / Q000382:microbiology; D011401:Promoter Regions, Genetic; D013559:Symbiosis; D014158:Transcription, Genetic; D020577:Wolbachia / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements
keywords: Bacteria; Transcription; Transposable elements