Name: Andrew Lang

Email: aslang@mun.ca

Author: Andrew Lang

Author affiliation: Memorial University of Newfoundland

Abstract title: Gene Transfer Agents - Rhodobacter and beyond

Absstract:

The bacterium Rhodobacter capsulatus produces an unusual genetic exchange vector called the Gene Transfer Agent (RcGTA). RcGTA morphologically resembles a tailed bacteriophage and transfers ~4-kb fragments of genomic DNA between R. capsulatus cells. The RcGTA particle is encoded in a ~15-kb cluster of genes in the R. capsulatus genome, and the production of RcGTA is controlled by at least two cellular regulatory systems: two-component phosphorelay signal transduction and quorum sensing. We are currently working to understand these cellular regulatory systems and identify the specific triggers that govern RcGTA production. Genome sequencing has shown that highly conserved RcGTA-like gene clusters are present in many other alpha-proteobacteria, most notably in almost all species within the order Rhodobacterales. This includes the Roseobacter clade, and species in this group are abundant in diverse marine environments. We have examined the diversity of GTA genes in several environments, and this demonstrates that marine systems contain a diverse collection of GTA genes that distribute throughout the different Rhodobacterales lineages. We have also been working with Rhodobacterales isolates and demonstrated that a number of strains, from multiple locations, express the GTA major capsid protein, providing evidence that the widespread conservation of GTA genes in the Rhodobacterales may represent functionally similar and active GTA systems in these important lineages.