Intracellular Sorting and Translocation of Proteins into Plant Peroxisomes

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9604501 Trelease Technical Compartmentation of metabolic pathways within cellular organelles is a major aspect of the regulatory mechanisms that operate within eukaryotic cells. Proper intracellular sorting and translocation of proteins into the correct organelle are essential components of subcellular compartmentation. Peroxisomes conduct a diverse array of metabolic functions which depend on the cell or tissue type in which they reside. The overall goal of the research is to experimentally define the means by which glyoxysomes (a specialized type of peroxisome) in plant cells acquire proteins from their site of synthesis in the cytosol. Experiments will be done with the well-characterized in-vivo protein import system, namely suspension-cultured tobacco BY-2 cells. Objective 1 will be to determine the C-terminal positioning and variation of amino acid residues which are sufficient for proper sorting of chimepic proteins to BY-2 glyoxysomes via the PTS1 pathway. Objective 2 will be to elucidate the positioning and variation of amino acid residues within a N-terminal nanopeptide which sorts proteins to glyoxysomes via the PTS2 pathway. In concert with these objectives, studies will be initiated to identify and characterize putative membrane proteins involved in translocation of proteins through the boundary membrane of plant glyoxysomes. Non-technical Plant cells contain an intracellular organelle termed peroxisome that functions in the metabolism of sugars and fatty acids. How the peroxisome is assembled has been a major controversy in cell biology. The mechanism of how proteins are directed to various subcellular compartments is through targeting sequences that are an intrinsic part of the protein. Dr. Trelease will conduct research to determine the exact sequences necessary to target proteins to be incorporated into peroxisomes. ***