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

Abstract

After exposure to 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 Ced system, which imports DNA. We investigated several genes that are upregulated after UV exposure to identify potential exporters in the Ced system. We created in-frame deletion mutants and performed cell aggregation and DNA exchange assays. This led to the discovery of two novel components of 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 data shed new light on the fascinating DNA damage response of Sulfolobales.