Characterization of ori and parS-like functions in secondary genome replicons in .

The mechanisms underlying multipartite genome maintenance and its functional significance in extraordinary radioresistance of are not well understood. The sequences upstream to operons in chrII () and MP () could stabilize an otherwise, non-replicative plasmid, in DnaA and cognate ParB proteins bound specifically with and elements. The Δ and Δ cells showed the reduced copy number of cognate replicons and radioresistance as compared with wild type. Fluorescent reporter-operator system inserted in chrI, chrII, and MP in wild type and mutants showed the presence of all three replicons in wild-type cells. Although chrI was present in all the Δ and Δ cells, nearly half of these cells had chrII and MP, respectively, and the other half had the reduced number of foci representing these replications. These results suggested that and elements contain both and -like functions and the secondary genome replicons (chrII and MP) are maintained independent of chrI and have roles in radioresistance of .