Cell cycle regulation in the hyperthermophilic crenarchaeon Sulfolobus acidocaldarius

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 c hromosome replication and genome segregation. In contrast, multiple rounds of replication of the chromosome could occur in the absence of an interveni ng cell division event. Inhibition of the elongation stage of chromosome re plication resulted in cell division arrest, indicating that pathways simila r to checkpoint mechanisms in eukaryotes, and the SOS system of bacteria, a lso exist in archaea. Several antibiotics induced cell cycle arrest in the G(2) stage. Analysis of the run-out kinetics of chromosome replication duri ng the treatments allowed estimation of the minimal rate of replication for k 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 even ts. Possible targets for the antibiotics are discussed, including topoisome rases and protein glycosylation.