RT Journal Article
SR Electronic
T1 Molecular Analysis of the Interaction of Anthrax Adenylyl Cyclase Toxin, Edema Factor, with 2′(3′)-<em>O</em>-(<em>N</em>-(methyl)anthraniloyl)-Substituted Purine and Pyrimidine Nucleotides
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 693
OP 703
DO 10.1124/mol.108.052340
VO 75
IS 3
A1 Hesham M. Taha
A1 Jennifer Schmidt
A1 Martin Göttle
A1 Srividya Suryanarayana
A1 Yuequan Shen
A1 Wei-Jen Tang
A1 Andreas Gille
A1 Jens Geduhn
A1 Burkhard König
A1 Stefan Dove
A1 Roland Seifert
YR 2009
UL http://molpharm.aspetjournals.org/content/75/3/693.abstract
AB Bacillus anthracis causes anthrax disease and exerts its deleterious effects by the release of three exotoxins: lethal factor, protective antigen, and edema factor (EF), a highly active calmodulin-dependent adenylyl cyclase (AC). However, conventional antibiotic treatment is ineffective against either toxemia or antibiotic-resistant strains. Thus, more effective drugs for anthrax treatment are needed. Previous studies from our laboratory showed that mammalian membranous AC (mAC) exhibits broad specificity for purine and pyrimidine nucleotides ( Mol Pharmacol:-886, 2006 ). Here, we investigated structural requirements for EF inhibition by natural purine and pyrimidine nucleotides and nucleotides modified with N-methylanthraniloyl (MANT)- or anthraniloyl groups at the 2′(3′)-O-ribosyl position. MANT-CTP was the most potent EF inhibitor (Ki, 100 nM) among 16 compounds studied. MANT-nucleotides inhibited EF competitively. Activation of EF by calmodulin resulted in effective fluorescence resonance energy transfer (FRET) from tryptophan and tyrosine residues located in the vicinity of the catalytic site to MANT-ATP, but FRET to MANT-CTP was only small. Mutagenesis studies revealed that Phe586 is crucial for FRET to MANT-ATP and MANT-CTP and that the mutations N583Q, K353A, and K353R differentially alter the inhibitory potencies of MANT-ATP and MANT-CTP. Docking approaches relying on crystal structures of EF indicate similar binding modes of the MANT nucleotides with subtle differences in the region of the nucleobases. In conclusion, like mAC, EF accommodates both purine and pyrimidine nucleotides. The unique preference of EF for the base cytosine offers an excellent starting point for the development of potent and selective EF inhibitors. The American Society for Pharmacology and Experimental Therapeutics