Identification of type II toxin-antitoxin modules in Burkholderia pseudomallei

Type II toxinantitoxin (TA) systems are believed to be widely distributed amongst bacteria although their biological functions are not clear. We have identified eight candidate TA systems in the genome of the human pathogen Burkholderia pseudomallei. Five of these were located in genome islands. Of the candidate toxins, BPSL0175 (RelE1) or BPSS1060 (RelE2) caused growth to cease when expressed in Escherichia coli, whereas expression of BPSS0390 (HicA) or BPSS1584 (HipA) (in an E. coli Delta hipBA background) caused a reduction in the number of culturable bacteria. The cognate antitoxins could restore growth and culturability of cells.