Edema factor (EF)

Edema factor is a bacterial exotoxin enzyme secreted by Bacillus anthracis and is a principal virulence factor in anthrax disease. It is an adenylyl cyclase that becomes highly active upon binding to calmodulin inside host cells, converting ATP to cyclic AMP at rates much higher than mammalian enzymes. The resulting surge in cAMP disrupts immune cell function, impairs host defense mechanisms, and causes fluid accumulation (edema), favoring bacterial spread and survival. EF acts synergistically with protective antigen (forming "edema toxin") and is structurally distinct from mammalian adenylyl cyclases, which makes it a plausible therapeutic target for future anti-anthrax strategies[1][5][7].

Other names

Anthrax edema factorBacillus anthracis edema factorEF

Enzymatic conversion of ATP to cAMP upon activation by host calmodulin, leading to dysregulation of host cell signaling pathways[1][7] Forms part of "edema toxin" when combined with protective antigen (PA)[5] Requires entry into host cells via PA-mediated translocation[5][8]