| Project/Area Number |
18570111
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural biochemistry
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| Research Institution | Kyushu University |
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Principal Investigator |
TAMURA Shigehiko Kyushu University, Faculty of Science, Associate Professor (90236753)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIKI Yukio Kyushu University, Faculty of Science, Professor (70261237)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥4,040,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥540,000)
Fiscal Year 2007: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | peroxisome / organelle / AAA protein / Peroxin / peroxisome biogenesis disorder / 変異部位解析 |
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| Research Abstract |
Two peroxins, Pexlp and Pex6p, of the AAA protein family are responsible for peroxisome biogenesis disorders (PBDs) such as Zellweger syndrome of complementation group 1 (CG1) and CG4, respectively. These peroxins were recruited to peroxisomal membrane by Pex26p and suggested to be involved in the export from peroxisomes of Pex5p, the soluble recycling receptor for PTS1 matrix proteins. Furthermore, we recently reported that Pexlp was present partly in cytosol without forming a Pexlp-Pex6p-Pex26p complex. However, the molecular mechanism of the recycling system for Pex5p is not well understood. Therefore we investigated the role of AAA peroxins on peroxisomal membrane as well as in the cytosol. Co-immunoprecipitation and pull-down assays showed that Pex26p is competent to bind to Pex14p associated with Pex5p. The Pex26p-Pex14p complex was dissociated by Pexlp and Pex6p in an ATP-dependent manner. Blue-Native gel analysis of the cytosolic fraction from HEK293 cells and recombinant protein showed that Pex1p is mostly in a homo-trimer. In the assays for Pex5p oligomer structure in CHO-K1 cells, cytosolic Pex5p showed both dimer and monomer forms, although cytosolic Pex5p from Pex1p-deficient ZP107 cells was predominantly in a monomer form. Taken together, Pexlp-Pex6p complexes are likely to modulate the interaction of Pex26p and Pex14p, presumably releasing Pex5p from Pex14p. Furthermore, homo-trimer of Pexlp complexes were suggested to be involved in the conversion from a monomer to a dimer of cytosolic Pex5p. We discussed the sequential role of AAA peroxins in peroxisomal protein import and Pex5p recycling.
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