Structural highlights
Function
[CYAA_BACAN] One of the three proteins composing the anthrax toxin, the agent which infects many mammalian species and that may cause death. EF is a calmodulin-dependent adenylyl cyclase that, when associated with PA, causes edema. EF is not toxic by itself and it is required for the survival of germinated spores within macrophages at the early stages of infection. Provokes dramatic elevation of intracellular cAMP levels in the host.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Edema factor (EF) and CyaA are calmodulin (CaM)-activated adenylyl cyclase exotoxins involved in the pathogenesis of anthrax and whooping cough, respectively. Using spectroscopic, enzyme kinetic and surface plasmon resonance spectroscopy analyses, we show that low Ca(2+) concentrations increase the affinity of CaM for EF and CyaA causing their activation, but higher Ca(2+) concentrations directly inhibit catalysis. Both events occur in a physiologically relevant range of Ca(2+) concentrations. Despite the similarity in Ca(2+) sensitivity, EF and CyaA have substantial differences in CaM binding and activation. CyaA has 100-fold higher affinity for CaM than EF. CaM has N- and C-terminal globular domains, each binding two Ca(2+) ions. CyaA can be fully activated by CaM mutants with one defective C-terminal Ca(2+)-binding site or by either terminal domain of CaM while EF cannot. EF consists of a catalytic core and a helical domain, and both are required for CaM activation of EF. Mutations that decrease the interaction of the helical domain with the catalytic core create an enzyme with higher sensitivity to Ca(2+)-CaM activation. However, CyaA is fully activated by CaM without the domain corresponding to the helical domain of EF.
Physiological calcium concentrations regulate calmodulin binding and catalysis of adenylyl cyclase exotoxins.,Shen Y, Lee YS, Soelaiman S, Bergson P, Lu D, Chen A, Beckingham K, Grabarek Z, Mrksich M, Tang WJ EMBO J. 2002 Dec 16;21(24):6721-32. PMID:12485993[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Shen Y, Lee YS, Soelaiman S, Bergson P, Lu D, Chen A, Beckingham K, Grabarek Z, Mrksich M, Tang WJ. Physiological calcium concentrations regulate calmodulin binding and catalysis of adenylyl cyclase exotoxins. EMBO J. 2002 Dec 16;21(24):6721-32. PMID:12485993
