DynaTweezers · Elucidating the Molecular Mechanisms of Bacterial Gene Silencing using Tethered Particles and Optical Tweezing

DynaTweezers: Elucidating the Molecular Mechanisms of Bacterial Gene Silencing using Tethered Particles and Optical Tweezing

The rise of bacterial resistance to antimicrobial medication is a growing concern and each year an increasing number of hospitals report encountering bacteria resistant to all known antibiotics. Enteric (intestinal) bacteria in particular, have been identified as a reservoir for antibiotic resistant genes. An alarming example are bacteria that produce a single enzyme that can render the bacteria resistant to dozens of frontline antibiotics. The spread of antimicrobial resistance, both within bacteria species and between species, is greatly accelerated by the process of horizontal gene-transfer. Horizontal gene-transfer is a mechanism by which bacteria incorporate genetic elements obtained from other organisms into their own chromosome, and plays a major role in spreading virulence genes and antimicrobial-resistance genes. Getting new DNA from other organisms can allow the bacteria to adapt rapidly to external conditions. This can increase their fitness, or can decrease their fitness if harmful genes are expressed. To protect themselves from foreign (Xenogeneic) DNA, bacteria have developed an immune system based on proteins that bind to the bacterial DNA, the nucleoid: nucleoid associated proteins (NAPs). NAPs find and silence the expression of genetic material acquired from other organisms. However, how this silencing works is still unclear. The aim of my work is to clarify the molecular mechanisms by which NAPs (and related co-regulatory) proteins interact with DNA to silence the expression of this DNA. Several mechanisms have been hypothesized, based on experimental observations, but it is unclear which mechanism is dominant/correct and under which conditions. Understanding the mechanism by which NAPs silence the expression of genetic material may facilitate the development of medication with the specific aim of repressing or reverting antimicrobial resistance and virulence gene expression in bacteria. My work therefore aims to figure out how this works exactly. I develop a new biophysical method with a basis in well-established techniques to characterize these silencing mechanisms. Applying this technique, I can systematically characterize the effect that NAPs have on the transcription of specific DNA sequences, under a variety of local conditions to further our understanding of how Xenogeneic gene silencing occurs.

Data: CORDIS, © European Union