Abstract 1195 Structure-activity relationship studies of human carboxylesterases using a fluorogenic ester library

Peroxisomes are organelles present in all eukaryotic cells that are tasked with many metabolic functions, such as oxidating fatty acids and synthesizing some types of phospholipids.Despite their key role in life, they remain understudied.Current methods to study peroxisomes typically involve genetically encoded fluorescent proteins that are targeted to the peroxisomes using targeting sequences or fusion with known peroxisomal proteins.One such tool is pmscarlet which uses a peroxisome targeting signal 1 (PTS-1) sequence to bind with PEX5, a cytosolic receptor for peroxisomal protein import, resulting in its accumulation in the peroxisomes.In this study, we report that expression of pmscarlet interferes with normal PEX5 activity, which can lead to its mislocalization outside of the peroxisomes.As this significantly limits the utility of using pmscarlet to study peroxisomal biochemistry, we are working on approaches to address this problem.Overcoming this challenge will produce better tools to study the peroxisomes resulting in a more complete understanding the role of peroxisomes in life.