New components of the community-based DNA-repair mechanism in Sulfolobales

After exposure to ultraviolet (UV) light, Sulfolobus acidocaldarius cells aggregate in a species-specific manner to exchange DNA and repair double-strand breaks via homologous recombination. The formation of cell-cell interactions is mediated by Ups pili. DNA exchange subsequently occurs through the Crenarchaeal system for exchange of DNA (Ced), which imports DNA. To identify novel players in these processes, we investigated that several genes upregulated after UV exposure, by creating in-frame deletion mutants and performing cell aggregation and DNA exchange assays. This led to the identification of two novel components involved in the Ups and Ced systems: UpsC, a minor pilin of the Ups pili, and CedD, a VirD4-like ATPase essential for DNA import. Altogether, these findings provide new insights into the DNA damage response mechanisms in Sulfolobales.