Bacterial conjugation is a key mechanism of horizontal gene transfer, driving the spread of antimicrobial resistance (AMR) genes. This process relies on the Type IV secretion system (T4SS), a multi-protein complex embedded in the cell envelope of the donor cells. This secretion machinery mediates the unidirectional transfer of DNA from bacterial cells carrying conjugative plasmids to recipient cells. Despite significant progress in understanding T4SS-mediated DNA transfer, the precise structural dynamics of substrate translocation remains unclear.
In collaboration with the group of Dr. Debnath Ghosal at the University of Melbourne, we aim to elucidate the secretion pathway of conjugative plasmids in F-like T4SS. We develop reporter systems for the structural and dynamic characterization of the T4SS during active conjugation. Specifically, we generate translational and transcriptional fusion reporters designed to visualize the secretion machinery in its DNA transfer state. By integrating these reporters with fluorescence microscopy and cryo-electron tomography, we seek to resolve the structural transitions associated with DNA translocation through the T4SS and bacterial cell envelopes. By identifying key structural elements involved in DNA transfer, our work will advance the mechanistic understanding of bacterial conjugation. Ultimately, these insights may facilitate the development of novel strategies to disrupt conjugation, offering a potential means to mitigate the spread of AMR genes.
