Identification of a toxin coding fragment in pBSSB1, a linear plasmid from Salmonella enterica serovar Typhi that can stabilize a multicopy plasmid

• Published in: Asian Pacific Journal of Tropical Biomedicine
• Main Authors: Sunjukta Ahsan, David Summers
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wolters Kluwer Medknow Publications 2018
• Subjects: linear plasmid; pbssb2; salmonella enterica serovar typhi; Arctic medicine. Tropical medicine; RC955-962; Biology (General); QH301-705.5; Arctic
• Online Access: https://doi.org/10.4103/2221-1691.237080; https://doaj.org/article/b5e1b38b5c7541dd84420864bf32c9f1

Objective: To identify the region conferring stability to pBSSB2 (a linear plasmid, pBSSB1, containing a kanamycin cassette), which is unique to Indonesian isolates of Salmonella enterica serovar Typhi. Methods: The open reading frame (ORF) 009 was identified as a toxin coding gene in the plasmid through introduction of translational termination codons in the ORF. Results: The stability function was located in a fragment that spanned nucleotides 5 766 to 6 828 in the linear plasmid genetic map. Ectopic expression of ORF009 in pBAD18 vector indicated ORF009 codes for a toxin. This fragment could stabilize plasmid pUC18 previously destabilized through mutation of the pcnB (plasmid copy number control) gene that codes for polyA polymerase. Majority of the cells expressing ORF009 were non-viable according to phase contrast microscopy. Conclusions: This study demonstrated that a linear plasmid fragment that carries a gene encoding a toxin possibly conferred stability to the parent plasmid. It was able to stabilize a multicopy plasmid of Escherichia coli.