1y0v
From Proteopedia
Crystal structure of anthrax edema factor (EF) in complex with calmodulin and pyrophosphate
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. [CALM_XENLA] Calmodulin mediates the control of a large number of enzymes, ion channels and other proteins by Ca(2+). Among the enzymes to be stimulated by the calmodulin-Ca(2+) complex are a number of protein kinases and phosphatases. 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 PubMedEdema factor (EF), a key anthrax exotoxin, has an anthrax protective antigen-binding domain (PABD) and a calmodulin (CaM)-activated adenylyl cyclase domain. Here, we report the crystal structures of CaM-bound EF, revealing the architecture of EF PABD. CaM has N- and C-terminal domains and each domain can bind two calcium ions. Calcium binding induces the conformational change of CaM from closed to open. Structures of the EF-CaM complex show how EF locks the N-terminal domain of CaM into a closed conformation regardless of its calcium-loading state. This represents a mechanism of how CaM effector alters the calcium affinity of CaM and uncouples the conformational change of CaM from calcium loading. Furthermore, structures of EF-CaM complexed with nucleotides show that EF uses two-metal-ion catalysis, a prevalent mechanism in DNA and RNA polymerases. A histidine (H351) further facilitates the catalysis of EF by activating a water to deprotonate 3'OH of ATP. Mammalian adenylyl cyclases share no structural similarity with EF and they also use two-metal-ion catalysis, suggesting the catalytic mechanism-driven convergent evolution of two structurally diverse adenylyl cyclases. Calcium-independent calmodulin binding and two-metal-ion catalytic mechanism of anthrax edema factor.,Shen Y, Zhukovskaya NL, Guo Q, Florian J, Tang WJ EMBO J. 2005 Mar 9;24(5):929-41. Epub 2005 Feb 17. PMID:15719022[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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