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
The simplest model of quorum sensing requires a single constitutively expressed signaling molecule. In reality, bacterial quorum-sensing are part of a large regulatory networks, often with multiple quorum-sensing systems interlocked with other environmental sensors. A continuous effort of our group is to understand the implication of such complexity and the evolutionary and ecological forces that guide it
Quorum-sensing in mobile genetic elements
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.
Control of microbial populations may shed new light on the problem of division of labor between bacteria. Down the road, it 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 systems which will regulate spatially structured populations and communities at the single cell level.
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.
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.
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.
Current funding agencies: