PhD ceremony Mr. M. Ajon: Type IV pili dependent DNA repair in sulfolobales

PhD ceremony: Mr. M. Ajon, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Type IV pili dependent DNA repair in sulfolobales

Promotor(s): prof. A.J.M. Driessen

Faculty: Mathematics and Natural Sciences

Sulfolobus species are hyperthermophilic Crenarchaeota that live in extremely hot and acidic environments. Maintenance of the genomic integrity under such conditions is crucial for cellular viability. The thesis of Matgorzata Ajon describes a novel UV-inducible DNA exchange system present in these organisms. Upon UV stress, Sulfolobus species show a highly induced transcription of the so-called ups-gene cluster (UV-inducible pili operon of Sulfolobus). The ups-operon is involved in type IV pili formation and cellular aggregation of UV-irradiated cells. Furthermore, chromosomal DNA exchange increases the survival rates of Sulfolobus cells under DNA damaging conditions. It is suggested that the ups system is involved in DNA transfer within a population of Sulfolobus cells and that this process is needed to repair UV-damaged DNA via homologous recombination.