The long term objective of this research is to understand the biogenesis of peroxisomes in molecular detail. Peroxisomes are nearly ubiquitous in eukaryotic cells an have essential functions, including fatty acid catabolism an the first steps in plasmalogen biosynthesis. Peroxisomes grow by the posttranslational import of newly-synthesized proteins. Three types of targeting information may direct proteins to peroxisomes: noncleaved C-terminal tripeptides (typically SKL), N-terminal cleaved oligopeptides, or internal topogenic domains. Import involves receptors (one for SKL identified) and a translocation apparatus that requires ATP hydrolysis. New peroxisomes from by division of preexisting ones. Several fatal inherited disorders (Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum disease) are cause by defective peroxisome biogenesis; peoxisomal membranes assemble, but the import of matrix proteins does not occur. Peroxisomes in S. cerevisiae and are required for growth on, fatty acids. We developed a positive selection procedure with which we have identified novel mutants that are defective in peroxisome biogenesis (peb). Two apparently lack peroxisomes and resemble Zellweger syndrome. Two have clusters of normal-looking peroxisomes which are selectively defective in the import of subsets of peroxisomal proteins. The data imply the existence of three branches in the peroxisomal import pathway (or three pathways). We have cloned and sequenced a previously unknown gene that complements one of the new mutants. We have also purified peroxisomes of S. cerevisiae and established as in vitro import system with them.
The specific aims, in brief, are; A. Clone and analyze the genes required for peroxisome biogenesis that are defective in our peb mutants. B. Determine the properties, intracellular locations and functions of the peroxisome biogenesis gene products. C. Analyze the cellular defects in the mutants. D. Investigate the topological and functional relationships between proteins that participate in peroxisome assembly. E. Identify and characterize the corresponding human genes, if possible. F. Isolate additional mutants with new properties. These studies should provide fundamental new information about an intriguing problem in cell biology, peroxisome biogenesis, for which limited molecular information is yet available. They may also shed light on several human diseases in which peroxisome assembly in defective.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK019394-18
Application #
2137313
Study Section
Molecular Cytology Study Section (CTY)
Project Start
1976-05-01
Project End
1998-12-31
Budget Start
1995-01-01
Budget End
1995-12-31
Support Year
18
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Mount Sinai School of Medicine
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
City
New York
State
NY
Country
United States
Zip Code
10029
Nair, Devi M; Purdue, P Edward; Lazarow, Paul B (2004) Pex7p translocates in and out of peroxisomes in Saccharomyces cerevisiae. J Cell Biol 167:599-604
Lazarow, Paul B (2003) Peroxisome biogenesis: advances and conundrums. Curr Opin Cell Biol 15:489-97
Yang, X; Purdue, P E; Lazarow, P B (2001) Eci1p uses a PTS1 to enter peroxisomes: either its own or that of a partner, Dci1p. Eur J Cell Biol 80:126-38
Purdue, P E; Lazarow, P B (2001) Peroxisome biogenesis. Annu Rev Cell Dev Biol 17:701-52
Purdue, P E; Lazarow, P B (2001) Pex18p is constitutively degraded during peroxisome biogenesis. J Biol Chem 276:47684-9
Santos, M J; Henderson, S C; Moser, A B et al. (2000) Peroxisomal ghosts are intracellular structures distinct from lysosomal compartments in Zellweger syndrome: a confocal laser scanning microscopy study. Biol Cell 92:85-94
Purdue, P E; Skoneczny, M; Yang, X et al. (1999) Rhizomelic chondrodysplasia punctata, a peroxisomal biogenesis disorder caused by defects in Pex7p, a peroxisomal protein import receptor: a minireview. Neurochem Res 24:581-6
Purdue, P E; Yang, X; Lazarow, P B (1998) Pex18p and Pex21p, a novel pair of related peroxins essential for peroxisomal targeting by the PTS2 pathway. J Cell Biol 143:1859-69
Purdue, P E; Zhang, J W; Skoneczny, M et al. (1997) Rhizomelic chondrodysplasia punctata is caused by deficiency of human PEX7, a homologue of the yeast PTS2 receptor. Nat Genet 15:381-4
Zhang, J W; Lazarow, P B (1996) Peb1p (Pas7p) is an intraperoxisomal receptor for the NH2-terminal, type 2, peroxisomal targeting sequence of thiolase: Peb1p itself is targeted to peroxisomes by an NH2-terminal peptide. J Cell Biol 132:325-34

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