Overexpression analysis of sigZ of B. cereus ATCC 14579.. Bacillus cereus ATCC 14579

The Bacillus cereus ATCC 14579 alternative s factor sZ and its putative regulon have been characterized. sZ shows overall similarity with ECF s factors and sigZ constitutes an operon together with asfZ encoding its putative anti-s factor. Expression analysis revealed sigZ to be induced by an array of stresses, including exposure to ethanol, alkaline pH and heat shock, and a typical promoter binding site for the sigZ-operon was identified by 5’RACE. Phenotypic characterization of B. cereus ATCC 14579 and its sigZ-deletion strain revealed diminished growth performance and sporulation capacity. The sZ-regulon was successfully established by transcriptome analysis of a nisin inducible sigZ-overexpression strain. Overexpression of sigZ was shown to affect expression of 42 genes, including 33 genes encoding proteins located in the extracytoplasm. The identified sZ regulon contained genes encoding proteins situated in the extracytoplasm involved in cell surface modifications and transport. The regulation of genes encoding cell surface modification proteins implies sZ to be involved in the regulation of interaction of B. cereus ATCC 14579 with its environments, which includes human intestinal cells, possibly influencing its virulence status. Keywords: Comparative transcriptome study Overall design: Both an empty vector strain and an sigZ overexpressing strain were grown to an OD600 of ~0.5, after which 0.2 ng/ml nisin was added to both cultures. After 90 minutes from both cultures a sample was taken for RNA isolation. Comparisons performed were in duplicate with dye swap, the empty vector strain after 90 min nisin with the overexpressing strain after 90 min nisin.