Extracytoplasmic adenylate cyclase of Bordetella pertussis.

Abstract

Soluble adenylate cyclase [EC 4.6.1.1] accumulates in the culture medium of exponentially growing B. pertussis (300-900 pmol of c[cyclic]AMP formed/min per ml of 24 hr culture supernatant). There is also an extracytoplasmic adenylate cyclase which enables the intact organisms to form [32P]cAMP from exogenous [.alpha.-32P]ATP (200-1200 nmol of cAMP formed/min per g wet weight of cells) and which comprises 20-45% of the total adenylate cyclase activity. Only 1.7 and 2.4% of the total cell malate dehydrogenase [EC 1.1.1.37] and alkaline phosphatase [EC 3.1.3.1], respectively, are detectable in the intact cell. Trypsin [from bovine pancreas] treatment of intact organisms destroys 96% of the extracytoplasmic adenylate cyclase, but does not reduce the total cell malate dehydrogenase or a small pool of intracellular adenylate cyclase. Four compartments of adenylate cyclase in B. pertussis are proposed: soluble enzyme in the culture supernatant (up to 20% of the total activity); enzyme associated with intact cells and measurable without cell disruption (20-45%) extracytoplasmic enzyme sensitive to trypsin, but not measurable in intact cells at standard substrate concentrations (40-60%); and intracellular enzyme (7-9%). The extracytoplasmic location of the B. pertussis enzyme appears to be unique.