Activation of guanylate cyclase → ↑ cGMP

• Enterotoxigenic E. coli (ETEC): Heat-stable toxin

cAMP

Overactivate adenylate cyclase → ↑ cAMP

• Enterotoxigenic E. coli (ETEC): Heat-labile toxin

Activation of Gs protein → overactivation of adenylate cyclase → ↑ cAMP

• V. cholerae

Inhibition of Gi protein → adenylate cyclase disinhibition → cAMP accumulation

• B. pertussis

Edema factor (EF): binds to calcium and calmodulin and gains adenylate cyclase activity → ↑ cAMP

• B. anthracis