Genome sequencing and comparative analysis of Wolbachia strain wAlbA reveals Wolbachia-associated plasmids are common

Area of Science:

• Microbiology
• Genomics
• Symbiosis

Background:

• Wolbachia are maternally-inherited bacteria in arthropods, often inducing reproductive manipulation via cytoplasmic incompatibility (CI).
• Prophage regions in Wolbachia genomes encode cif genes essential for CI, but the prevalence of other genetic elements like plasmids is unclear.
• Previous research identified a plasmid in Wolbachia strain wPip, but its commonality across Wolbachia species remained unknown.

Purpose of the Study:

• To investigate the prevalence and genetic content of plasmids in Wolbachia strains.
• To characterize the genome of Wolbachia strain wAlbA from Aedes albopictus.
• To explore the potential role of plasmids in Wolbachia-host interactions and CI.

Main Methods:

• Sequencing the complete genome of Wolbachia strain wAlbA after removing the co-infecting wAlbB strain.
• Bioinformatic analysis of publicly available Wolbachia genome datasets to identify plasmids and chromosomal islands.
• Comparative analysis of plasmid-encoded genes, including homologues of cif genes.

Main Results:

• The wAlbA genome is associated with two novel plasmids.
• Plasmids and related chromosomal islands were identified in over 20% of analyzed Wolbachia genome datasets.
• These plasmids encode accessory genes, including phage-related genes and potential host-interaction factors, with divergent cif gene homologues found on both Wolbachia- and Rickettsia-associated plasmids.

Conclusions:

• Plasmids are a common feature of Wolbachia genomes, not just limited to specific strains.
• The presence of accessory genes on these plasmids suggests diverse functions, potentially impacting host-symbiont interactions and CI.
• This research provides crucial insights for developing genetic tools for Wolbachia manipulation and understanding their symbiotic roles.