Acyl-Homoserine Lactone-Based Quorum Sensing in Members of the Marine Bacterial Roseobacter Clade: Complex Cell-to-Cell Communication Controls Multiple Physiologies

When functioning in concert, bacterial populations are able to influence their local environment in ways unachievable by individual cells. Synchronous activities in bacteria can be accomplished through the use of quorum-sensing (QS) systems that employ small diffusible molecules to coordinate gene expression, principally in a cell density-dependent manner. The most commonly described QS signaling molecules in Gram-negative bacteria are N-acyl-homoserine lactones (AHLs). Members of the abundant marine Roseobacter lineage possess AHL-based QS systems and are environmentally relevant models for understanding the role of QS toward ecological success of these heterotrophic marine bacteria in the oceans. As reviewed here, recent studies indicate that the roles of QS in roseobacters are both varied and complex. An analysis of 78 publically available Roseobacter genomes demonstrates conservation of QS protein sequences as well as their gene organization among clade members. These findings support the hypothesis that QS is both conserved and widespread in this important group of bacteria.