Wolbachia Prophage DNA Adenine Methyltransferase Genes in Different Drosophila-Wolbachia Associations

Wolbachia is an obligatory intracellular bacterium which often manipulates the reproduction of its insect and isopod hosts. In contrast, Wolbachia is an essential symbiont in filarial nematodes. Lately, Wolbachia has been implicated in genomic imprinting of host DNA through cytosine methylation. The importance of DNA methylation in cell fate and biology calls for in depth studing of putative methylation-related genes. We present a molecular and phylogenetic analysis of a putative DNA adenine methyltransferase encoded by a prophage in the Wolbachia genome. Two slightly different copies of the gene, met1 and met2, exhibit a different distribution over various Wolbachia strains. The met2 gene is present in the majority of strains, in wAu, however, it contains a frameshift caused by a 2 bp deletion. Phylogenetic analysis of the met2 DNA sequences suggests a long association of the gene with the Wolbachia host strains. In addition, our analysis provides evidence for previously unnoticed multiple infections, the detection of which is critical for the molecular elucidation of modification and/or rescue mechanism of cytoplasmic incompatibility

Insect lines and <i>Wolbachia</i> strains used in the present study.

<p>Insect lines and <i>Wolbachia</i> strains used in the present study.</p

Southern blot analysis of <i>met</i> genes using genomic DNA from different <i>Wolbachia</i> infected species.

<p>The blot was hybridized with a probe corresponding to the full length <i>met1</i> (<b>A</b>) and <i>met2</i> (<b>B</b>) genes from <i>w</i>Mel.</p

PCR primers used in the present study.

<p>PCR primers used in the present study.</p

PCR analysis of <i>met2</i> copies in <i>Wolbachia</i> strain <i>w</i>Tei.

<p>PCR was performed using primers met_102F and met_269R (<b>A</b>), met_1024R (<b>B</b>) or TeiB_1024R (<b>C</b>). Primers met_102F and met_269R detect both A-group- and B-group-like <i>met2</i>, met_1024R detects only A-group-like <i>met2</i>, while TeiB_1024R detects only B-group-like <i>met2</i>. M: 100 base pair molecular weight DNA marker (New England Biolabs).</p

Phylogenetic tree of <i>Wolbachia</i> based on <i>met</i> gene sequences.

<p>The tree was constructed by Maximum Likelihood analysis. Numbers on the nodes indicate bootstrap values.</p

Distribution of phage methyltransferases in <i>resc</i>+ and <i>resc</i>− <i>Wolbachia</i> strains.

<p>Distribution of phage methyltransferases in <i>resc</i>+ and <i>resc</i>− <i>Wolbachia</i> strains.</p