dnaA gene sequences from Wolbachia pipientis support subdivision into supergroups and provide no evidence for recombination in the lineages infecting nematodes

摘要

Wolbachia pipientis is an intracellular bacterial endosymbiont of arthropods and filarial nematodes. Six main supergroups of W. pipientis have been described: supergroups A, B, E, and F encompass arthropod wolbachiae; supergroups C and D encompass nematode wolbachiae. The description of these six supergroups has been based on the analysis of only two genes (ftsZ and 16S rDNA) and before decisions are taken on the taxonomic status of the six supergroups, analysis of further genes is required. In addition, the branching order of the six supergroups is still unresolved. Sequence information from other genes is also needed to allow phylogenesis to be addressed through the analysis of a higher number of characters. Here we report sequences from a portionof the gene coding for the DNAA protein of W. pipientis, generated from the endosymbionts of 22 host species. Phytogenies based on dnaA gene sequences are congruent with the existence of at least six supergroups of W. pipientis. In addition, subtrees generated for nematode wolbachiae in supergroups C and D were compared to the trees based on the already available gene sequences (ftsZ, 16S rDNA and wsp). The congruence observed among the trees based on the different genes agrees with the hypothesis thatrecombination does not occur in nematode wolbachiae.