Bacterial quorum sensing
Quorum sensing is a process of chemical communication that bacteria use to monitor cell density and coordinate cooperative behaviors. Quorum sensing relies on the secretion of small signal molecules and expression of cognate receptor pairs. Quorum sensing has evolved independently multiple times and show patterns of both evolutionary convergence and divergence, allowing us to use it as a model system of simple sociality.
Our lab is studying quorum-sensing systems from a multi-disciplinary view by combining approaches from microbiology, systems biology and evolutionary biology. As model organisms we use the species Bacillus subtilis and Pseudomonas aeruginosa - arguably the best studied model organisms for Gram-positive and Gram-negative quorum-sensing systems.
Some of the specific questions we are interested in include:
Design principles of bacterial quorum-sensing networks
While the simplest model of quorum sensing requires a single constitutively expressed signaling molecule. Many bacteria, however, have multiple signaling systems which are often interlinked in complex regulatory networks. We study why cells use multiple quorum-sensing systems and what the design principles behind their interactions are.
Divergence of bacterial quorum-sensing specificity
Gram-positive bacteria, which use peptides as signaling molecules, often show very high level of divergence of their receptor-signal pairs. We use a variety of tools to probe the evolutionary divergence of specificity. We try to understand what selects for the maintenance of multiple different specificity groups, what processes underlies the co-evolution of receptor and signaling molecule, what can be inferred from the molecular patterns of diversity, and what structural features potentiate differentiation at the molecular level.
Control of microbial populations may allow better design of metabolic applications in biotechnology and microbiome regulation in medical and agricultural applications.
Our recent identification of short-range communication in bacteria allows us to create novel synthetic control system to control spatially structured populations at the single cell level.
Evolution of resistance to quorum-sensing inhibition
Quorum-sensing mediates virulence in a variety of pathogenic bacteria, making it a potential target for the design of specific drugs. The social nature of quorum sensing may lead to a different evolutionary path for resistant strains than that of antibiotic resistance. We combine in-lab evolution, genetics and theoretical analysis to study the evolution of quorum-sensing inhibition resistance.
Quorum-sensing and the evolution of interaction between host and mobile-element
Quorum-sensing has been shown to guide the transmission of plasmids, integrative and conjugative elements and phages. We combine quantitative analysis, genetics, microscopy and modeling to understand the interplay between communication systems, mobile elements and bacteria.
Quorum-sensing and biofilm development
We study the regulation of biofilm formation by quorum-sensing systems and the way by which the biofilm environment modulates quorum-sensing signal transduction.
Current funding agencies: