Identification and characterization of a novel toxin-antitoxin module from Bacillus anthracis

Shivangi Agarwal, Shivani Agarwal, Rakesh Bhatnagar*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Comparative genome analysis of Bacillus anthracis revealed a pair of linked genes encoding pemK (K, killer protein) and pemI (I, inhibitory protein) homologous to pem loci of other organisms. Expression of PemK in Escherichia coli and Bacillus anthracis was bacteriostatic whereas the concomitant expression of PemI reversed the growth arrest. PemK expression effectively inhibited protein synthesis with no significant effect on DNA replication. Coexpression and interaction of these proteins confirmed it to be a Type II addiction module. Thermal denaturation analysis reflected poor conformational stability of PemI as compared to PemK. Circular dichroism analysis indicated that PemI contains twice the amount of β-sheets as PemK. Gel retardation assays demonstrated that PemI binds to its upstream DNA sequence. This study reports the first evidence of an active chromosome encoded toxin-antitoxin locus in B. anthracis.

Original languageEnglish (US)
Pages (from-to)1727-1734
Number of pages8
JournalFEBS Letters
Issue number9
StatePublished - May 1 2007


  • Addiction module
  • Bacillus anthracis
  • Plasmid inheritance
  • Post segregational killing
  • Toxin-antitoxin locus

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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