DNA methylation enhances cooperative disentanglement by the Hfq nucleoid-associated protein

The Hfq protein is not only a mediator of RNA metabolism but also a key structural element involved in nucleic acid shaping. Its ability to compact and organize DNA, as well as its influence on the dynamics of various DNA-related processes, makes Hfq a central player in the regulation of bacterial chromosomal architecture and function. We previously demonstrated that different DNA methylation states affect Hfq binding and mobility. In this study, we show that Hfq, through its C-terminal region, can influence a DNA entangled/disentangled transition and examine the impact of DNA methylation on this previously uncharacterized function of Hfq. This discovery provides new insights into the role of Hfq in DNA transactions, with potential implications for essential cellular processes such as recombination and replication. Furthermore, this study demonstrates that Synchrotron Radiation Linear Dichroism (SRLD) is a powerful tool that can follow cooperative vs non-cooperative protein induced DNA structural transitions.