Cell cycle regulation in the hyperthermophilic crenarchaeon Sulfolobus acidocaldarius

Abstract

The regulation and co‐ordination of the cell cycle of the hyperthermophilic crenarchaeon Sulfolobus acidocaldarius was investigated with antibiotics. We provide evidence for a core regulation involving alternating rounds of chromosome replication and genome segregation. In contrast, multiple rounds of replication of the chromosome could occur in the absence of an intervening cell division event. Inhibition of the elongation stage of chromosome replication resulted in cell division arrest, indicating that pathways similar to checkpoint mechanisms in eukaryotes, and the SOS system of bacteria, also exist in archaea. Several antibiotics induced cell cycle arrest in the G₂ stage. Analysis of the run‐out kinetics of chromosome replication during the treatments allowed estimation of the minimal rate of replication fork movement in vivo to 250 bp s⁻¹. An efficient method for the production of synchronized Sulfolobus populations by transient daunomycin treatment is presented, providing opportunities for studies of cell cycle‐specific events. Possible targets for the antibiotics are discussed, including topoisomerases and protein glycosylation.