scholarly journals Molecular Requirements for Peroxisomal Targeting of Alanine-Glyoxylate Aminotransferase as an Essential Determinant in Primary Hyperoxaluria Type 1

PLoS Biology ◽  
2012 ◽  
Vol 10 (4) ◽  
pp. e1001309 ◽  
Author(s):  
Krisztián Fodor ◽  
Janina Wolf ◽  
Ralf Erdmann ◽  
Wolfgang Schliebs ◽  
Matthias Wilmanns
Keyword(s):  
Primary Hyperoxaluria ◽  
Primary Hyperoxaluria Type 1 ◽  
Primary Hyperoxaluria Type ◽  
Peroxisomal Targeting ◽  
Glyoxylate Aminotransferase ◽  
Hyperoxaluria Type

scholarly journals Mammalian alanine/glyoxylate aminotransferase 1 is imported into peroxisomes via the PTS1 translocation pathway. Increased degeneracy and context specificity of the mammalian PTS1 motif and implications for the peroxisome-to-mitochondrion mistargeting of AGT in primary hyperoxaluria type 1.

1995 ◽  
Vol 131 (1) ◽  
pp. 95-109 ◽  
Author(s):  
A Motley ◽  
M J Lumb ◽  
P B Oatey ◽  
P R Jennings ◽  
P A De Zoysa ◽  
...  
Keyword(s):  
Amino Acid ◽  
Primary Hyperoxaluria ◽  
Primary Hyperoxaluria Type 1 ◽  
Peroxisomal Protein ◽  
Primary Hyperoxaluria Type ◽  
Peroxisomal Targeting ◽  
Translocation Pathway ◽  
Glyoxylate Aminotransferase ◽  
Hyperoxaluria Type

Alanine/glyoxylate aminotransferase 1 (AGT) is peroxisomal in most normal humans, but in some patients with the hereditary disease primary hyperoxaluria type 1 (PH1), AGT is mislocalized to the mitochondria. In an attempt to identify the sequences in AGT that mediate its targeting to peroxisomes, and to determine the mechanism by which AGT is mistargeted in PH1, we have studied the intracellular compartmentalization of various normal and mutant AGT polypeptides in normal human fibroblasts and cell lines with selective deficiencies of peroxisomal protein import, using immunofluorescence microscopy after intranuclear microinjection of AGT expression plasmids. The results show that AGT is imported into peroxisomes via the peroxisomal targeting sequence type 1 (PTS1) translocation pathway. Although the COOH-terminal KKL of human AGT was shown to be necessary for its peroxisomal import, this tripeptide was unable to direct the peroxisomal import of the bona fide peroxisomal protein firefly luciferase or the reporter protein bacterial chloramphenicol acetyltransferase. An ill-defined region immediately upstream of the COOH-terminal KKL was also found to be necessary for the peroxisomal import of AGT, but again this region was found to be insufficient to direct the peroxisomal import of chloramphenicol acetyltransferase. Substitution of the COOH-terminal KKL of human AGT by the COOH-terminal tripeptides found in the AGTs of other mammalian species (SQL, NKL), the prototypical PTS1 (SKL), or the glycosomal PTS1 (SSL) also allowed peroxisomal targeting, showing that the allowable PTS1 motif in AGT is considerably more degenerate than, or at least very different from, that acceptable in luciferase. AGT possessing the two amino acid substitutions responsible for its mistargeting in PH1 (i.e., Pro11-->Leu and Gly170-->Arg) was targeted mainly to the mitochondria. However, AGTs possessing each amino acid substitution on its own were targeted normally to the peroxisomes. This suggests that Gly170-->Arg-mediated increased functional efficiency of the otherwise weak mitochondrial targeting sequence (generated by the Pro11-->Leu polymorphism) is not due to interference with the peroxisomal targeting or import of AGT.

Fetal liver alanine: Glyoxylate aminotransferase and the prenatal diagnosis of primary hyperoxaluria type 1

1989 ◽  
Vol 9 (4) ◽  
pp. 271-281 ◽  
Author(s):  
Christopher J. Danpure ◽  
Patricia R. Jennings ◽  
Richard J. Penketh ◽  
Pauline J. Wise ◽  
Penelope J. Cooper ◽  
...  
Keyword(s):  
Prenatal Diagnosis ◽  
Fetal Liver ◽  
Primary Hyperoxaluria ◽  
Primary Hyperoxaluria Type 1 ◽  
Primary Hyperoxaluria Type ◽  
Glyoxylate Aminotransferase ◽  
Hyperoxaluria Type

scholarly journals Identification of mutations associated with peroxisome-to-mitochondrion mistargeting of alanine/glyoxylate aminotransferase in primary hyperoxaluria type 1.

1990 ◽  
Vol 111 (6) ◽  
pp. 2341-2351 ◽  
Author(s):  
P E Purdue ◽  
Y Takada ◽  
C J Danpure
Keyword(s):  
Normal Population ◽  
Primary Hyperoxaluria ◽  
Alpha Helix ◽  
Primary Hyperoxaluria Type 1 ◽  
Peroxisomal Enzyme ◽  
Primary Hyperoxaluria Type ◽  
Oligonucleotide Hybridization ◽  
Glyoxylate Aminotransferase ◽  
Hyperoxaluria Type

We have previously shown that in some patients with primary hyperoxaluria type 1 (PH1), disease is associated with mistargeting of the normally peroxisomal enzyme alanine/glyoxylate aminotransferase (AGT) to mitochondria (Danpure, C.J., P.J. Cooper, P.J. Wise, and P.R. Jennings. J. Cell Biol. 108:1345-1352). We have synthesized, amplified, cloned, and sequenced AGT cDNA from a PH1 patient with mitochondrial AGT (mAGT). This identified three point mutations that cause amino acid substitutions in the predicted AGT protein sequence. Using PCR and allele-specific oligonucleotide hybridization, a range of PH1 patients and controls were screened for these mutations. This revealed that all eight PH1 patients with mAGT carried at least one allele with the same three mutations. Two were homozygous for this allele and six were heterozygous. In at least three of the heterozygotes, it appeared that only the mutant allele was expressed. All three mutations were absent from PH1 patients lacking mAGT. One mutation encoding a Gly----Arg substitution at residue 170 was not found in any of the control individuals. However, the other two mutations, encoding Pro----Leu and Ile----Met substitutions at residues 11 and 340, respectively, cosegregated in the normal population at an allelic frequency of 5-10%. In an individual homozygous for this allele (substitutions at residues 11 and 340) only a small proportion of AGT appeared to be rerouted to mitochondria. It is suggested that the substitution at residue 11 generates an amphiphilic alpha-helix with characteristics similar to recognized mitochondrial targeting sequences, the full functional expression of which is dependent upon coexpression of the substitution at residue 170, which may induce defective peroxisomal import.

scholarly journals Immunocytochemical localization of human hepatic alanine: glyoxylate aminotransferase in control subjects and patients with primary hyperoxaluria type 1.

1988 ◽  
Vol 36 (10) ◽  
pp. 1285-1294 ◽  
Author(s):  
P J Cooper ◽  
C J Danpure ◽  
P J Wise ◽  
K M Guttridge
Keyword(s):  
Enzyme Activity ◽  
Protein A ◽  
Primary Hyperoxaluria ◽  
Primary Hyperoxaluria Type 1 ◽  
Peroxisomal Membrane ◽  
Peroxisomal Enzyme ◽  
Primary Hyperoxaluria Type ◽  
Glyoxylate Aminotransferase ◽  
Hyperoxaluria Type

Primary hyperoxaluria type 1 (PH1) is an inherited disorder of glyoxylate metabolism caused by a deficiency of the hepatic peroxisomal enzyme alanine: glyoxylate aminotransferase (AGT; EC 2.6.1.44) [FEBS Lett (1986) 201:20]. The aim of the present study was to investigate the intracellular distribution of immunoreactive AGT protein, using protein A-gold immunocytochemistry, in normal human liver and in livers of PH1 patients with (CRM+) or without (CRM-) immunologically crossreacting enzyme protein. In all CRM+ individuals, which included three controls, a PH1 heterozygote and a PH1 homozygote immunoreactive AGT protein was confined to peroxisomes, where it was randomly dispersed throughout the peroxisomal matrix with no obvious association with the peroxisomal membrane. No AGT protein could be detected in the peroxisomes or other cytoplasmic compartments in the livers of CRM- PH1 patients (homozygotes). The peroxisomal labeling density in the CRM+ PH1 patient, who was completely deficient in AGT enzyme activity, was similar to that of the controls. In addition, in the PH1 heterozygote, who had one third normal AGT enzyme activity, peroxisomal labeling density was reduced to 50% of normal.

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