Influence of Disulfide Bonds on the Conformation of the Antifungal Protein from Oliver

The three-dimensional structure of a cysteine rich antifungal protein EAFP2 is found to be compact and extremely stable.The rigid nature of the protein is attributed to the presence of five disulfide bonds.However, the effect of individual disulfide bonds on the conformation has not been characterized.Thus, Molecular Dynamics (MD) simulations are used to explicate the influence of disulfide bonds on the conformation.In the present study, the cysteine residues in the native structure are mutated to alanine and the structural characteristics and conformational dynamics of the native and mutant structures are analyzed to better understand the effect of disulfide bonds on the tertiary structure.The simulated native and single mutant structures are found to posses similar conformations, indicating that loss of disulfide bond did not affect the tertiary structure conformation greatly.However, in the single mutant (C7A) structure, the N and C-terminal segments are found to be different.It is also interesting to note that the loss of disulfide bond between Cys35 and Cys39 actually resulted in a more compact structure.