Communication of bacterial cells to each other, called quorum sensing, is an important mechanism to control their population. By "talking" to each other with chemical signals, bacterial cells can decide if the present conditions are favorable for their multiplication and formation of biofilms. Detection and inhibition of the quorum sensing provides novel possibilities for treating bacterial infections with theranostics (combination of diagnostics and therapy). This EAGER project addresses fundamental aspects of the quorum sensing analysis and its inhibition based on a nano-technological approach using molecular "machines" assembled on magnetic nanoparticles and activated at a distance with an external magnetic field. Success will open future biomedical applications and other potential applications in environmental studies (e.g., for the analysis and enhancement of water remediation efficiency) and homeland security (such as preventing bioterrorism).
Quorum sensing is a mechanism of gene regulation triggered by small molecules sensed by bacteria in order to control the density of bacterial population depending on available resources. Disruption of this mechanism using small molecules is a novel strategy to combat pathogenic bacteria. The importance and advantage of identifying such potential drugs is that by signaling bacteria with "disinformation", bacteria are not threatened, hence have no incentive to develop resistance to the drug (unlike with conventional antibiotics). Thus, these drugs are expected to be in the forefront of antibacterial treatments, when antibiotics could not be used anymore. The proposed research program will make use of a novel class of Magnetic Field-activated Molecular Machines that will be developed within the project framework. These new machines will be used as unique biosensor devices that will enter the cells and will report (upon magnetic stimulation) on the concentration of different genes in their transcribed form (mRNA) that are in charge of sensing between bacteria. The reporting signal will be fluorescent and will be quantified. The fluorescent signal will be an indication of the quantities of mRNA molecules that exist in the cells. This approach can be taken both for the quantification of multiple genes, but also for the screening of potential drugs (out of potential drug libraries) that inhibit the sensing of small molecules between bacteria. Since in vivo quantification of mRNA is considered a realistic representation of the state of cells at a given time point, this approach can be expected to be highly productive in the analysis of quorum sensing in bacteria and then its inhibition. The expected results will include novel quorum sensing inhibitors that may be used as new antibacterial reagents to fight Pseudomonas aeruginosa related infections (in the future other bacterial infections). Specific objectives include: (i) a proof of concept that the molecular machines described can enter bacterial cells and detect mRNAs, (ii) specific detection of mRNAs and their quantification, (iii) biosensing of low concentrations of mRNAs upon down regulation of quorum sensing in the presence of inhibitors, (iv) and the use of these molecular machines in high-throughput screens of quorum sensing inhibitors operating as novel anti-bacterial drugs.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
