Unveiling Novel Virulence Factors from Burkholderia cepacia Complex

The nematode Caenorhabditis elegans was used as an infection model to screen a random plasposon mutagenesis collection of 2500 mutants, derived from either Burkholderia cenocepacia K56-2 or J2315. This work focussed on the study of the P4A1 mutant derived from B. cenocepacia K56-2, carrying a Tn5 insertion interrupting the pbr gene, encoding a putative protein 50% identical to the stringent response regulator SocE of Myxococcus xanthus. Upstream of pbr, we identified two putative genes encoding proteins 97% and 91% identical, respectively, to the PhzD and PhzF from Pseudomonas chlororaphis, involved in phenazine biosynthesis. The sequencing analysis of the chromosomal regions flanking the Tn5 interrupted genes in three attenuated mutants derived from B. cenocepacia J2315, showed that the plasposon insertion occurred, respectively, in a 5S rRNA gene, in the region between the 5S rRNA encoding gene and the 23S rRNA encoding gene, or in a putative gene, encoding a conserved hypothetical protein of unknown function, exhibiting a significant structural similarity to the LysR family of transcription regulators.