Abstract:
pBSSB1 is a 27 kb non-bacteriophage-related linear plasmid first found in Salmonella enterica serovar Typhi (S. Typhi), but
the mechanism underlying the replication of pBSSB1 is currently unknown. Previous reports showed that the factor for
inversion stimulation (Fis) encoded by fis can affect the replication, transcription and other processes through binding DNA.
Here, a fis deletion mutant of S. Typhi (Dfis) was prepared through the homologous recombination mediated by suicide
plasmid and the loss of pBSSB1 in Dfis was observed surprisingly by pulsed field gel electrophoresis (PFGE). Subsequently,
the loss of pBSSB1 was verified by PCR and Southern blot. In addition, the motility of Dfis was deficient and the flagellin of
Dfis could not be detected by 2-dimensional polyacrylamide gel electrophoresis. All these results show that Fis is essential
for the stability of pBSSB1 and affects the motility of S. Typhi.
