Structure and Function of the Chromosome Replication Origin.

is the leading bacterial cause of foodborne infections worldwide. However, our understanding of its cell cycle is poor. We identified the probable origin of replication () - a key element for initiation of chromosome replication, which is also important for chromosome structure, maintenance and dynamics. The herein characterized is monopartite and contains (i) the DnaA box cluster, (ii) the DnaA-dependent DNA unwinding element (DUE) and (iii) binding sites for regulatory proteins. The cluster of five DnaA boxes and the DUE were found in the intergenic region. Binding of DnaA to this cluster of DnaA-boxes enabled unwinding of the DUE . However, it was not sufficient to sustain replication of minichromosomes, unless the cluster was extended by additional DnaA boxes located in the 3' end of . This suggests, that requires these boxes to initiate or to regulate replication of its chromosome. However, further detailed mutagenesis is required to confirm the role of these two boxes in initiation of chromosome replication and thus to confirm partial localization of within a coding region, which has not been reported thus far for any bacterial . DUE unwinding by DnaA was inhibited by Cj1509, an orphan response regulator and a homolog of HP1021, that has been previously shown to inhibit replication in . Thus, Cj1509 might play a similar role as a regulator of chromosome replication. This is the first systematic analysis of chromosome replication initiation in , and we expect that these studies will provide a basis for future research examining the structure and dynamics of the chromosome, which will be crucial for understanding the pathogens' life cycle and virulence.