Functional Analysis of Early-acting Peroxins in Matrix Protein Import

William Marsh Rice University, Houston TX

Investigators

Abstract

Peroxisomes are cellular compartments that house a variety of processes. In plants, peroxisomal enzymes catalyze numerous critical metabolic reactions, including fatty acid breakdown, certain photosynthesis-related reactions, and metabolism of several hormones. A distinguishing and remarkable feature of peroxisomes is their ability to import folded and even multimeric cargo proteins. Most proteins necessary for building peroxisomes (peroxins) are dedicated to importing peroxisomal enzymes from the cytoplasm, where the proteins are synthesized. A broad outline has emerged that describes how proteins are imported into animal, fungal, and plant peroxisomes. Whereas some elements of peroxisome biogenesis appear to be universal, other components display surprising variability. It is therefore critical to examine these import proteins in greater detail to define their roles in plants. This project will elucidate the molecular mechanisms of peroxisome protein import in plants by analyzing peroxin mutants in the reference plant Arabidopsis thaliana for peroxisome defective phenotypes, peroxisomal protein import, and receptor levels. Genetic and physical interactions among the peroxins will provide insight into how the peroxins work together. A genetic screen will provide a means to discover peroxins unique to plants or not yet discovered in other systems by taking advantage of, without being limited by, what is known in other systems. Characterizing plant peroxisomal protein import will reveal the roles of genes critical for the function and assembly of plant peroxisomes, and will reveal the divergent and conserved facets of this process among plants, animals, and fungi. In addition to investigating peroxisome functions, this research will provide undergraduate, graduate, and postdoctoral researchers with the broad interdisciplinary training bridging genomics, molecular genetics, cell biology, and biochemistry that will be essential to the emerging generation of scientists. Rice University and the PI are committed to training and educating both graduate and undergraduate students while continuing to foster the participation of individuals from underrepresented groups in research.