Disclosed herein are nucleic acid sequences that encode pro-apoptotic polypeptides. Also disclosed are polypeptides encoded by these nucleic acid sequences, and antibodies, which immunospecifically-bind to the polypeptide, as well as derivatives, variants, mutants, or fragments of the aforementioned polypeptide, polynucleotide, or antibody. The invention further discloses therapeutic, diagnostic and research methods for diagnosis, treatment, and prevention of proliferative disorders and bacterial infections using the nucleic acids and proteins of the invention.