Characterization of a novel plasmid, pSW, isolated from Salmonella enterica servar Typhimurium JOL401

Salmonella enterica serovar Typhimurium JOL401 was isolated from chicken in South Korea. A novel plasmid, pSW, harbored in JOL401, consists of 2,216 base pairs (bps) and three putative open reading frames (ORFs). pSW was 86 and 82% homologous to pSGI15 from Salmonella enterica and pJHCMW1 from Klebsiella pneumonia, respectively, both of which are ColE1-type plasmids that undergo theta-type replication. ORF1 of pSW exhibited 98% identity and 99% positive to ORF1 of pJHCMW1, which encodes a putative transmembrane protein. ORF2 of pSW was homologous to sequences that encode replication initiators in pSGI15 and pJHCMW1, exhibiting a high degree of homology to the putative replication initiator of pJHCMW1. Thus, ORF2 appeared to encode the pSW replication initiator. ORF3 of pSW, which exhibited similarity to ORF2 of pSGI15, remains undefined. Newly isolated pSW is a member of the ColE1-type family of plasmids and consists of three putative ORFs, of which one, ORF2, is a strong candidate for the gene encoding the pSW replication initiator.   Key words: pSW, plasmid, ColE1, replication initiator, pSGI15, pJHCMW1