Neutralization of Bacterial YoeB_Spn Toxicity and Enhanced Plant Growth in Arabidopsis thaliana via Co-Expression of the Toxin-Antitoxin Genes

Bacterial toxin-antitoxin (TA) systems have various cellular functions, including as part of the general stress response. The genome of the Gram-positive human pathogen Streptococcus pneumoniae harbors several putative TA systems, including yefM-yoeB_Spn, which is one of four systems that had been demonstrated to be biologically functional. Overexpression of the yoeB_Spn toxin gene resulted in cell stasis and eventually cell death in its native host, as well as in Escherichia coli. Our previous work showed that induced expression of a yoeB_Spn toxin-Green Fluorescent Protein (GFP) fusion gene apparently triggered apoptosis and was lethal in the model plant, Arabidopsis thaliana. In this study, we investigated the effects of co-expression of the yefM_Spn antitoxin and yoeB_Spn toxin-GFP fusion in transgenic A. thaliana. When co-expressed in Arabidopsis, the YefM_Spn antitoxin was found to neutralize the toxicity of YoeB_Spn-GFP. Interestingly, the inducible expression of both yefM_Spn antitoxin and yoeB_Spn toxin-GFP fusion in transgenic hybrid Arabidopsis resulted in larger rosette leaves and taller plants with a higher number of inflorescence stems and increased silique production. To our knowledge, this is the first demonstration of a prokaryotic antitoxin neutralizing its cognate toxin in plant cells. View Full-Text