title: E3 ubiquitin ligase SP1 regulates peroxisome biogenesis in Arabidopsis.
abstract: Peroxisomes are ubiquitous eukaryotic organelles that play pivotal roles in a suite of metabolic processes and often act coordinately with other organelles, such as chloroplasts and mitochondria. Peroxisomes import proteins to the peroxisome matrix by peroxins (PEX proteins), but how the function of the PEX proteins is regulated is poorly understood. In this study, we identified the Arabidopsis RING (really interesting new gene) type E3 ubiquitin ligase SP1 [suppressor of plastid protein import locus 1 (ppi1) 1] as a peroxisome membrane protein with a regulatory role in peroxisome protein import. SP1 interacts physically with the two components of the peroxisome protein docking complex PEX13-PEX14 and the (RING)-finger peroxin PEX2. Loss of SP1 function suppresses defects of the pex14-2 and pex13-1 mutants, and SP1 is involved in the degradation of PEX13 and possibly PEX14 and all three RING peroxins. An in vivo ubiquitination assay showed that SP1 has the ability to promote PEX13 ubiquitination. Our study has revealed that, in addition to its previously reported function in chloroplast biogenesis, SP1 plays a role in peroxisome biogenesis. The same E3 ubiquitin ligase promotes the destabilization of components of two distinct protein-import machineries, indicating that degradation of organelle biogenesis factors by the ubiquitin-proteasome system may constitute an important regulatory mechanism in coordinating the biogenesis of metabolically linked organelles in eukaryotes.
authors: Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824.
authors: Ronghui
authors: R
authors: Pan
authors: Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824.
authors: John
authors: J
authors: Satkovich
authors: Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824; huji@msu.edu.|Plant Biology Department, Michigan State University, East Lansing, MI 48824.
authors: Jianping
authors: 0000-0002-4635-4299
authors: J
authors: Hu
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D001678:Organelle Biogenesis; D000074401:Peroxins / Q000235:genetics / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D000074401:Peroxins; D044767:Ubiquitin-Protein Ligases
keywords: E3 ubiquitin ligase; SP1; peroxin; peroxisome biogenesis; protein import