PprA Protein Is Involved in Chromosome Segregation via Its Physical and Functional Interaction with DNA Gyrase in Irradiated Deinococcus radiodurans Bacteria

Alice Devigne (1, 2) , Philippe Guérin (3) , Johnny Lisboa (2) , Sophie Quevillon-Cheruel (4, 2) , J. Armengaud (3) , Suzanne Sommer (2, 1) , Claire Bouthier de La Tour (2, 1) , Pascale Servant (2, 1)

1 RBA - Radiorésistance des bactéries et des archées
2 I2BC - Institut de Biologie Intégrative de la Cellule
3 LI2D - Laboratoire Innovations technologiques pour la Détection et le Diagnostic
4 FAAM - Fonction et Architecture des Assemblages Macromoléculaires

PprA, a radiation-induced Deinococcus-specific protein, was previously shown to be required for cell survival and accurate chromosome segregation after exposure to ionizing radiation. Here, we used an in vivo approach to determine, by shotgun proteomics, putative PprA partners coimmunoprecipitating with PprA when cells were exposed to gamma rays. Among them, we found the two subunits of DNA gyrase and, thus, chose to focus our work on characterizing the activities of the deinococcal DNA gyrase in the presence or absence of PprA. Loss of PprA rendered cells hypersensitive to novobiocin, an inhibitor of the B subunit of DNA gyrase. We showed that treatment of bacteria with novobiocin resulted in induction of the radiation desiccation response (RDR) regulon and in defects in chromosome segregation that were aggravated by the absence of PprA. In vitro, the deinococcal DNA gyrase, like other bacterial DNA gyrases, possesses DNA negative supercoiling and decatenation activities. These two activities are inhibited in vitro by novobiocin and nalidixic acid, whereas PprA specifically stimulates the decatenation activity of DNA gyrase. Together, these results suggest that PprA plays a major role in chromosome decatenation via its interaction with the deinococcal DNA gyrase when D. radiodurans cells are recovering from exposure to ionizing radiation.

Mots clés: Deinococcus radiodurans; PprA; DNA gyrase; DNA decatenation

Domaines: Sciences du Vivant [q-bio]

Alice Devigne, Philippe Guérin, Johnny Lisboa, Sophie Quevillon-Cheruel, J. Armengaud, et al.. PprA Protein Is Involved in Chromosome Segregation via Its Physical and Functional Interaction with DNA Gyrase in Irradiated Deinococcus radiodurans Bacteria. MSphere, 2016, ⟨10.1128/mSphere.00036-15⟩. ⟨hal-01412363⟩