In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 104, No. 27 ( 2007-07-03), p. 11501-11506
Abstract:
Glyoxysomes are a subclass of peroxisomes involved in lipid mobilization. Two distinct peroxisomal targeting signals (PTSs), the C-terminal PTS1 and the N-terminal PTS2, are defined. Processing of the PTS2 on protein import is conserved in higher eukaryotes. The cleavage site typically contains a Cys at P1 or P2. We purified the glyoxysomal processing protease (GPP) from the fat-storing cotyledons of watermelon ( Citrullus vulgaris ) by column chromatography, preparative native isoelectric focusing, and 2D PAGE. The GPP appears in two forms, a 72-kDa monomer and a 144-kDa dimer, which are in equilibrium with one another. The equilibrium is shifted on Ca 2+ removal toward the monomer and on Ca 2+ addition toward the dimer. The monomer is a general degrading protease and is activated by denatured proteins. The dimer constitutes the processing protease because the substrate specificity proven for the monomer (Φ-Arg/Lys↓) is different from the processing substrate specificity (Cys-Xxx↓/Xxx-Cys↓) found with the mixture of monomer and dimer. The Arabidopsis genome analysis disclosed three proteases predicted to be in peroxisomes, a Deg-protease, a pitrilysin-like metallopeptidase, and a Lon-protease. Specific antibodies against the peroxisomal Deg-protease from Arabidopsis (Deg15) identify the watermelon GPP as a Deg15. A knockout mutation in the DE G1 5 gene of Arabidopsis (At1g28320) prevents processing of the glyoxysomal malate dehydrogenase precursor to the mature form. Thus, the GPP/Deg15 belongs to a group of trypsin-like serine proteases with Escherichia coli DegP as a prototype. Nevertheless, the GPP/Deg15 possesses specific characteristics and is therefore a new subgroup within the Deg proteases.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.0704733104
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2007
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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