Evidence for a Putative Caspase-3-Like Protein in Stenotrophomonas maltophilia and Pseudomonas aeruginosa

Abstract

The process of apoptosis, or programmed cell death, involves proteolytic cascades mediated by caspase proteins. One protein that plays a central role in the induction of apoptosis, is caspase-3, a cysteinyl aspartate-specific protease. Although apoptosis is often characterized as a eukaryotic process, recent studies have demonstrated evidence for prokaryotic programmed cell death and have identified the presence of a caspase-3-like protein in Xanthomonas campestris. Therefore, in this study we tested for the presence of a caspase-3- like protein in a broad range of bacteria, including Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Bacillus subtilis, and Escherichia coli strains. We found evidence for both the expression of a caspase-3-like protein, as well as caspase-3 enzymatic activity in both Stenotrophomonas maltophilia and Pseudomonas aeruginosa. However, due to the preliminary nature of these studies, additional experiments are necessary to conclude that the presence and activity of a caspase-3-like protein are directly related to the process of apoptosis in prokaryotes.