Import of the Peroxisomal Targeting Signal Type 2 Protein 3-Ketoacyl-Coenzyme A Thiolase into Glyoxysomes1
AUTOR(ES)
Johnson, Tanya L.
FONTE
The American Society for Plant Biologists
RESUMO
Most peroxisomal matrix proteins possess a carboxy-terminal tripeptide targeting signal, termed peroxisomal targeting signal type 1 (PTS1), and follow a relatively well-characterized pathway of import into the organelle. The peroxisomal targeting signal type 2 (PTS2) pathway of peroxisomal matrix protein import is less well understood. In this study, we investigated the mechanisms of PTS2 protein binding and import using an optimized in vitro assay to reconstitute the transport events. The import of the PTS2 protein thiolase differed from PTS1 protein import in several ways. Thiolase import was slower than typical PTS1 protein import. Competition experiments with both PTS1 and PTS2 proteins revealed that PTS2 protein import was inhibited by addition of excess PTS2 protein, but it was enhanced by the addition of PTS1 proteins. Mature thiolase alone, lacking the PTS2 signal, was not imported into peroxisomes, confirming that the PTS2 signal is necessary for thiolase import. In competition experiments, mature thiolase did not affect the import of a PTS1 protein, but it did decrease the amount of radiolabeled full-length thiolase that was imported. This is consistent with a mechanism by which the mature protein competes with the full-length thiolase during assembly of an import complex at the surface of the membrane. Finally, the addition of zinc to PTS2 protein imports increased the level of thiolase bound and imported into the organelles.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=300750Documentos Relacionados
- A novel, cleavable peroxisomal targeting signal at the amino-terminus of the rat 3-ketoacyl-CoA thiolase.
- (+)-Abscisic Acid Metabolism, 3-Ketoacyl-Coenzyme A Synthase Gene Expression, and Very-Long-Chain Monounsaturated Fatty Acid Biosynthesis in Brassica napus Embryos1
- Oilseed isocitrate lyases lacking their essential type 1 peroxisomal targeting signal are piggybacked to glyoxysomes.
- Human peroxisomal 3-oxoacyl-coenzyme A thiolase deficiency.
- Internal targeting signal of the BCS1 protein: a novel mechanism of import into mitochondria.