Phage DNA dynamics in cells with different fates.

Bacteriophage λ begins its infection cycle by ejecting its DNA into its host Escherichia coli cell, after which either a lytic or a lysogenic pathway is followed, resulting in different cell fates. In this study, using a new technique to monitor the spatiotemporal dynamics of the phage DNA in vivo, we found that the phage DNA moves via two distinct modes, localized motion and motion spanning the whole cell. One or the other motion is preferred, depending on where the phage DNA is ejected into the cell. By examining the phage DNA trajectories, we found the motion to be subdiffusive. Moreover, phage DNA motion is the same in the early phase of the infection cycle, irrespective of whether the lytic or lysogenic pathway is followed; hence, cell-fate decision-making appears not to be correlated with the phage DNA motion. However, after the cell commits to one pathway or the other, phage DNA movement slows during the late phase of the lytic cycle, whereas it remains the same during the entire lysogenic cycle. Throughout the infection cycle, phage DNA prefers the regions around the quarter positions of the cell.