Exploring Caspase Mutations and Post-Translational Modification by Molecular Modeling Approaches

Apoptosis is a type of programmed cell death that eliminates damaged cells and controls the development and tissue homeostasis of multicellular organisms. Caspases, a family of cysteine proteases, play a key role in apoptosis initiation and execution. The maturation of caspases and their activity is fine-tuned by post-translational modifications in a highly dynamic fashion. To assess the effect of post-translational changes, potential sites are routinely mutated with residues persistent to any modifications. For example, the serine residue is replaced with alanine or aspartic acid. However, such substitutions could alter the caspase active site's conformation, leading to disturbances in catalytic activity and cellular functions. Moreover, mutations of other amino acid residues located in critical positions could also break the structure and functions of caspases and lead to apoptosis perturbation. To avoid the difficulties of employing mutated residues, molecular modeling approaches can be readily applied to estimate the potential effect of amino acid substitutions on caspase structure. The present protocol allows the modeling of both the wild-type caspase and its mutant forms with the biomolecular simulation package (Amber) and supercomputer facilities to test the effect of mutations on the protein structure and function.