Crystallization and preliminary X-ray study of the edema factor exotoxin adenylyl cyclase domain from Bacillus anthracis in the presence of its activator, calmodulin

Acta Crystallogr D Biol Crystallogr. 2001 Dec;57(Pt 12):1881-4. doi: 10.1107/s0907444901014937. Epub 2001 Nov 21.


Edema factor from Bacillus anthracis is a 92 kDa secreted adenylyl cyclase exotoxin and is activated by the host-resident protein calmodulin. Calmodulin is a ubiquitous intracellular calcium sensor in eukaryotes and activates edema factor nearly 1000-fold upon binding. While calmodulin has many known effectors, including kinases, phosphodiesterases, motor proteins, channels and type 1 adenylyl cyclases, no structures of calmodulin in complex with a functional enzyme have been solved. The crystallization and initial experimental phasing of crystals containing a complex of edema factor adenylyl cyclase domain and calmodulin are reported here. The edema factor-calmodulin complex crystallizes in three different space groups. A native data set in the I222 space group has been collected to 2.7 A and the self-rotation function solution suggests three edema factor-calmodulin complexes in each asymmetric unit. Initial 4 A phases were obtained by selenomethionyl MAD in combination with two heavy-atom derivatives. These phases were successfully extended to 2.7 A using NCS averaging.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenylyl Cyclases / chemistry*
  • Adenylyl Cyclases / metabolism
  • Antigens, Bacterial
  • Bacillus anthracis / chemistry*
  • Bacillus anthracis / enzymology
  • Bacterial Toxins
  • Calmodulin / chemistry*
  • Crystallization
  • Crystallography, X-Ray
  • Models, Molecular
  • Protein Conformation


  • Antigens, Bacterial
  • Bacterial Toxins
  • Calmodulin
  • anthrax toxin
  • Adenylyl Cyclases