Full expression of Bacillus anthracis toxin gene in the presence of bicarbonate requires a 2.7-kb-long atxA mRNA that contains a terminator structure.
Bacillus anthracis toxin gene expression requires AtxA, a virulence regulator that also activates capsule gene transcription and controls expression of more than a hundred genes. Here we report that atxA mRNA is 2.7-kb-long and ends, after a 500 nt-long 3' untranslated region, with a stem loop structure followed by a run of U's. The presence of this structure stabilizes atxA mRNA and is necessary for AtxA maximal accumulation, full expression of the PA toxin gene, pagA and optimal PA accumulation. This structure displays terminator activity independently of its orientation when cloned between an inducible promoter and a reporter gene. The 3.6-kb-long DNA fragment carrying both AtxA promoters and the terminator is sufficient for full expression of pagA in the presence of bicarbonate. No pXO1-encoded element other than the DNA fragment encompassing the 2.7 kb atxA transcript and the pagA promoter is required for bicarbonate induction of pagA transcription.
Bertin
Marine
M
Institut Pasteur, Unité Toxines et Pathogénie Bactérienne, CNRS, URA 2172, 28 rue du Dr Roux, 75724 Paris Cedex 15, France. marine.bertin@pasteur.fr
Château
Alice
A
Fouet
Agnès
A
D000942:Antigens, Bacterial / Q000235:genetics* / Q000378:metabolism; D001408:Bacillus anthracis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D001639:Bicarbonates / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D055029:Inverted Repeat Sequences; D009690:Nucleic Acid Conformation; D013728:Terminator Regions, Genetic; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
C082932:ATXA protein, Bacillus anthracis; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D001639:Bicarbonates; D015534:Trans-Activators; C030325:anthrax toxin