"Temperature regulation of the anthrax toxin genes in Bacillus subtilis"

MANSILLA MC; DE MENDOZA D

Iguazú, Argentina

Congreso; XL Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2004

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Anthrax, a potentially fatal disease of animals and man, is caused by the Gram-positive endospore-forming bacterium Bacillus anthracis. The anthrax toxin, one of its major virulence determinants, is a tri-partite molecule composed of a cell binding protein, termed protective antigen, the lethal factor and the edema factor. The toxin genes, pagA, cya and lef, are coordinately regulated at the level of transcription and are induced by bicarbonate and increase in temperature, but the mechanism of thermal regulation remains unsolved. Using pagA-lacZ transcriptional fusions we determined that expression of the protective antigen responds to temperature and to signals of stationary phase in a B. subtilis background, in the presence of the B. anthracis regulator AtxA. We also confirmed that transcription of the ORFs 90, 126 and lef coded in pOX1 is atxA-dependent, as had been observed in microarrays experiments, but only ORFs 90 and lef show temperature-dependent expression in a B. subtilis background. Since this effect is not mediated by an increase of AtxA protein, some other factor must be involved, and an homolog of this putative co-regulator of toxin genes transcription must be present in B. subtilis. We proved that the DesKR two-component system that senses temperature in this bacteria is not playing this role.