Bordetella pertussis Autoregulates Pertussis Toxin Production through the Metabolism of Cysteine JOHN A. BOGDAN,* JAVIER NAZARIO-LARRIEU, JAWAD SARWAR, PETER ALEXANDER, AND M. S. BLAKE Baxter Healthcare Corporation, Columbia, Maryland 21046-2358 Received 11 April 2001/Returned for modification 22 May 2001/Accepted 7 August 2001
Pertussis toxin (Ptx) expression and secretion in Bordetella pertussis are regulated by a two-component signal transduction system encoded by the bvg regulatory locus. However, it is not known whether the metabolic pathways and growth state of the bacterium influence synthesis and secretion of Ptx and other virulence factors. We have observed a reduction in the concentration of Ptx per optical density unit midway in fermentation. Studies were conducted to identify possible factors causing this reduction and to develop culture conditions that optimize Ptx expression. Medium reconstitution experiments demonstrated that spent medium and a fraction of this medium containing components with a molecular weight of
