Biotechnologie Kolloquium: Prof. Marc Bramkamp (Christian-Albrecht University of Kiel)

Gast: Prof. Marc Bramkamp (Christian-Albrecht University of Kiel)

Titel: A novel DNA damage-repair system DipABCD in Corynebacterium glutamicum

Zusammenfassung: The bacterial SOS response is a generalized mechanism that upon stress allows efficient DNA damage repair and pauses cell division to prevent the segregation of damaged chromosomes. In Corynebacterium glutamicum, a biotechnological workhorse and a model organism for the cell biology of Mycobacteriales, the SOS regulon comprises 48 genes, nearly half of which with unknown functions. We identified a new SOS-regulated operon dipABCD (DNA damage-induced proteins) and explored its role in DNA repair. CRISPRi-seq data and phenotypical assays confirmed that dip deletions affect other DNA repair and oxidative stress pathways. Through in vitro and in vivo approaches, we showed that the Dip system includes the GTP-regulated DNA nickase DipA and the helicase DipD that binds near DNA damage sites. Detailed characterization using various DNA damaging agents, suggest a role for the Dip system in double strand break repair. Although phenotpyes of a dip operon deletion are subtle, a mutant strain is outcompeted by the wild type rapidly under DNA-stress conditions. Single-molecule localization microscopy revealed that DipA influences the dynamics of the other Dip components, suggesting a functional interaction of the Dip components. Thus, the DNA nicking activity of DipA may be necessary for the DNA binding of other Dip proteins. Collectively, our findings point to a dedicated role for the Dip system in the repair of double strand DNA damage.