FlmA-FlmB toxin-antitoxin system

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Flmb SScons.png
Conserved secondary structure of flmB RNA.
Symbol FlmB
Other data
RNA type antisense RNA
Domain(s) E. coli, S. enterica
SO {{{SO}}}

The FlmA-FlmB toxin-antitoxin system consists of FlmB RNA (F leading-region maintenance B), a family of non-coding RNAs and the protein toxin FlmA. The FlmB RNA transcript is 100 nucleotides in length and is homologous to sok RNA from the hok/sok system and fulfills the identical function as a post-segregational killing (PSK) mechanism.[1][2]

flmB is found on the F-plasmid of Escherichia coli and Salmonella enterica. It is responsible for stabilising the plasmid. If the plasmid is not inherited, long-lived FlmA mRNA and protein will be highly toxic to the cell, possibly to the point of causing cell death.[2] Daughter cells which inherit the plasmid inherit the FlmB gene, coding for FlmB RNA which binds the leader sequence of FlmA mRNA and represses its translation.[1]

See also[edit]


  1. ^ a b Loh SM, Cram DS, Skurray RA (June 1988). "Nucleotide sequence and transcriptional analysis of a third function (Flm) involved in F-plasmid maintenance". Gene. 66 (2): 259–68. doi:10.1016/0378-1119(88)90362-9. PMID 3049248. 
  2. ^ a b Kobayashi M, Kurusu Y, Yukawa H (February 1991). "High-expression of a target gene and high-stability of the plasmid". Appl. Biochem. Biotechnol. 27 (2): 145–62. doi:10.1007/BF02921523. PMID 2029184. 

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