The Anthrax Protective Antigen (PA63) Bound Conformation of a Peptide Inhibitor of the Binding of Lethal Factor to PA63: As Determined by trNOESY NMR and Molecular Modelling
WALTER REED ARMY INST OF RESEARCH WASHINGTON DC DIV OF EXPERIMENTAL THERAPEUTICS
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Anthrax protective antigen PA is one of the three proteins produced by the gram positive bacteria Bacillus anthracis collectively known as the anthrax toxin. The role played by PA in anthrax intoxication is to transport the two enzymes lethal factor LF and edema factor EF into the cell. Collier and co-workers reported the isolation of two peptides via phage display that bind to the PA63 heptamer and inhibit its interaction with LF and EF, and thereby prevent the transport of LF and EF into the cell. One of these peptides was selected for structural investigation on the basis of its ability to prevent the binding of LF to the PA63 heptamer bundle. Two dimensional trNOESY experiments coupled with NOE restrained simulated annealing calculations were used to determine the PA63-bound conformation of P1. On binding to PA63, P1 adopts a helical conformation involving residues 3-9 while the C- and N-terminal residues exhibit dynamic fraying.
- Atomic and Molecular Physics and Spectroscopy
- Medicine and Medical Research