D. radiodurans shifts nucleoid morphology and spatial distribution of proteins in response to ionizing radiation

The bacterium Deinococcus radiodurans is highly resistant to ionizing radiation (IR), surviving exposures up to 10 kGy. Unlike the vast majority of bacteria, in which DNA is diffuse and spread throughout the cell volume, D. radiodurans maintains its genomic material in a constitutively-condensed state. It is thought that D. radiodurans' highly organized and condensed nucleoid may help protect its genome from IR and other forms of stress. In this project, we use fluorescence confocal microscopy and computational image analysis to quantify the morphology of nucleoids and the spatial distributions of nucleoid-associated proteins, both before and after exposure to IR. In prior work we have shown that irradiation shifts the cell populations toward morphologies with more nucleoid condensation and away from morphologies associated with cell division (Cordova, Niese, AEM, 2024). Here, we build on this prior work by showing that spatial distributions of nucleoid-associated proteins reorganize after irradiation. Demonstrating links between protein dynamics and morphological changes. These results provide a framework for understanding how nucleoid structure and protein behavior contribute to radiation tolerance.