title: Expression of the Streptococcus pneumoniae yoeB chromosomal toxin gene causes cell death in the model plant Arabidopsis thaliana.
abstract: BACKGROUND
  Bacterial toxin-antitoxin systems usually comprise of a pair of genes encoding a stable toxin and its cognate labile antitoxin and are located in the chromosome or in plasmids of several bacterial species. Chromosomally-encoded toxin-antitoxin systems are involved in bacterial stress responses and activation of the toxins usually leads to cell death or dormancy. Overexpression of the chromosomally-encoded YoeB toxin from the yefM-yoeB toxin-antitoxin locus of the Gram-positive bacterium Streptococcus pneumoniae has been shown to cause cell death in S. pneumoniae as well as E. coli.
  
  
  RESULTS
  Induction of a YoeB-GFP fusion protein using a 17-β-estradiol-inducible plant expression system in Arabidopsis thaliana Col 0, was lethal in all T2 progeny. Examination of plants by fluorescent confocal microscopy showed GFP fluorescence in all parts of the leaves at 24 hours after 17-β-estradiol induction, continuing up to plant death. Quantitative RT-PCR analysis revealed that the expression of the yoeB toxin gene peaked at 3 days after induction with 17-β-estradiol, coinciding with the onset of visible effects on the plants. Moreover, we detected DNA laddering in the transgenic plants at 24 hours after yoeB induction, indicative of apoptosis.
  
  
  CONCLUSIONS
  Expression of the YoeB toxin from Streptococcus pneumoniae is lethal in Arabidopsis. We believe this is the first report of a toxin from a bacterial toxin-antitoxin system functioning in plants. The results presented here mark an important milestone towards the development of a cell ablation based bio-containment strategy, which may be useful for functional studies and for the control of spread of transgenic plants.
authors.affiliation: Centre for Research in Biotechnology for Agriculture (CEBAR) and Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia. afung87@gmail.com.
authors.forename: Fauziah Abu
authors.initials: FA
authors.lastname: Bakar
authors.affiliation: Biomedical Research Centre, Faculty of Medicine, Universiti Sultan Zainal Abidin, Medical Campus, 20400, Kuala Terengganu, Malaysia. chewchieng@gmail.com.
authors.forename: Chew Chieng
authors.initials: CC
authors.lastname: Yeo
authors.affiliation: Centre for Research in Biotechnology for Agriculture (CEBAR) and Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia. jennihari@um.edu.my.
authors.forename: Jennifer Ann
authors.initials: JA
authors.lastname: Harikrishna
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004958:Estradiol / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D013296:Streptococcus pneumoniae / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D004958:Estradiol