American Society of Plant Biologists
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Poster: Cell Biology

Abs # P03058: The role of the cytoskeleton on the synthesis and import of peroxisomal matrix proteins

Presenter: Dahodwala, Murtaza A       Contact Presenter
AuthorsDahodwala, Murtaza A (A)   Vickerman, Lori A (A)   Michelle, Freeman C (A)   Muench, Douglas G (A)  
Affiliations: (A): University of Calgary, Department of Biological Sciences

Eukaryotic cells are highly organized and dynamic. These essential features enable cells to be energetically efficient in the functional roles that they fulfill. For instance, many cellular proteins are non-randomly localized throughout the cell cytoplasm or are targeted to cellular organelles. Protein synthesis and localization often requires the localization of its cognate mRNA followed by localized translation into protein. This mRNA localization is often dependent on the cytoskeleton for mRNA movement and anchoring. In an effort to identify proteins that have a role in mRNA localization and/or anchoring of mRNAs to the cytoskeleton, a biochemical screen was performed to identify proteins that possess both RNA and microtubule binding activities. This screen identified the peroxisomal multifunctional protein (MFP), a peroxisomal matrix protein with up to four activities involved in the β-oxidation of fatty acids. Peroxisomal malate dehydrogenase (pMDH) was later shown also to possess microtubule and RNA binding activities. This evidence of the RNA and microtubule binding activities for MFP and pMDH have led us to propose a working model wherein these proteins bind to their cognate mRNAs and to microtubules in the cytoplasm, resulting in translational repression in an autoregulated manner. Peroxisomes then import microtubule-bound MFP and pMDH, thereby de-repressing the synthesis of MFP and pMDH. We have studied the synthesis and import rate of these proteins using fluorescent protein fusions and pulse-chase immunoprecipitation experiments in the presence of cytoskeleton destabilizing agents. The results of these experiments will be presented.

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