Protein Transport In and Out of Plant Peroxisomes

Bartel, Bonnie; Burkhart, Sarah E.; Fleming, Wendell A.

doi:10.1007/978-3-7091-1788-0_14

Cited by 10 publications

(20 citation statements)

References 94 publications

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“…pex2-1 and pex10-2 are the first alleles of PEX2 and PEX10 to emerge from forward genetic screens for peroxisome defects in Arabidopsis. The isolation of pex2-1, which lacks dramatic physiological defects, adds to growing evidence that microscopy-based screens (Mano et al, 2006;Goto et al, 2011;Burkhart et al, 2013) can identify peroxisome-defective mutants with physiological defects too subtle to emerge from more common screens for reduced b-oxidation (for review, see Bartel et al, 2014a).…”

Section: Discussionmentioning

confidence: 99%

Peroxisomal Ubiquitin-Protein Ligases Peroxin2 and Peroxin10 Have Distinct But Synergistic Roles in Matrix Protein Import and Peroxin5 Retrotranslocation in Arabidopsis

2014

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Peroxisomal matrix proteins carry peroxisomal targeting signals (PTSs), PTS1 or PTS2, and are imported into the organelle with the assistance of peroxin (PEX) proteins. From a microscopy-based screen to identify Arabidopsis (Arabidopsis thaliana) mutants defective in matrix protein degradation, we isolated unique mutations in PEX2 and PEX10, which encode ubiquitin-protein ligases anchored in the peroxisomal membrane. In yeast (Saccharomyces cerevisiae), PEX2, PEX10, and a third ligase, PEX12, ubiquitinate a peroxisome matrix protein receptor, PEX5, allowing the PEX1 and PEX6 ATP-hydrolyzing enzymes to retrotranslocate PEX5 out of the membrane after cargo delivery. We found that the pex2-1 and pex10-2 Arabidopsis mutants exhibited defects in peroxisomal physiology and matrix protein import. Moreover, the pex2-1 pex10-2 double mutant exhibited severely impaired growth and synergistic physiological defects, suggesting that PEX2 and PEX10 function cooperatively in the wild type. The pex2-1 lesion restored the unusually low PEX5 levels in the pex6-1 mutant, implicating PEX2 in PEX5 degradation when retrotranslocation is impaired. PEX5 overexpression altered pex10-2 but not pex2-1 defects, suggesting that PEX10 facilitates PEX5 retrotranslocation from the peroxisomal membrane. Although the pex2-1 pex10-2 double mutant displayed severe import defects of both PTS1 and PTS2 proteins into peroxisomes, both pex2-1 and pex10-2 single mutants exhibited clear import defects of PTS1 proteins but apparently normal PTS2 import. A similar PTS1-specific pattern was observed in the pex4-1 ubiquitin-conjugating enzyme mutant. Our results indicate that Arabidopsis PEX2 and PEX10 cooperate to support import of matrix proteins into plant peroxisomes and suggest that some PTS2 import can still occur when PEX5 retrotranslocation is slowed.

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Section: Discussionmentioning

confidence: 99%

Peroxisomal Ubiquitin-Protein Ligases Peroxin2 and Peroxin10 Have Distinct But Synergistic Roles in Matrix Protein Import and Peroxin5 Retrotranslocation in Arabidopsis

2014

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“…A reverse-genetic screen for EMBRYO-DEFECTIVE (EMB) genes identified two insertional mutations in PEX1 (emb2817-1 and emb2817-2) that confer embryos arresting at the preglobular stage (http://www.seedgenes.org/; Muralla et al, 2011). Although mutants in almost all predicted single-gene peroxins have been isolated in forward-genetic screens for peroxisomal defects in Arabidopsis (for review, see Bartel et al, 2014), viable pex1 mutants have not been reported in plants. Here, we describe two Arabidopsis mutants in PEX1, pex1-2 and pex1-3, that display distinct peroxisome-related defects and harbor missense mutations in the region encoding the PEX1 D2.…”

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“…At a cellular level, defects in peroxisomal size, positioning, and matrix protein import can be visualized by tagging GFP with a PTS, which also has formed the basis of screens for mutants with peroxisome defects (Mano et al, 2006;Burkhart et al, 2013;Rinaldi et al, 2016). Because PTS2 cleavage occurs after import, mutations in peroxin genes often impair PTS2 processing (for review, see Bartel et al, 2014). The PTS2-processing protease DEG15 is a PTS1 protein (Helm et al, 2007), and so PTS2-processing defects can reflect PTS1 and/or PTS2 import defects.…”

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“…Arabidopsis is an oilseed plant that catabolizes triacylglycerol stored in the seed to support early seedling growth. Because peroxisomes are the sole site of fatty acid b-oxidation in plants (for review, see Graham, 2008), pex mutants can display reduced growth that is ameliorated by supplementation with an alternative fixed carbon source such as Suc (for review, see Bartel et al, 2014). Because peroxisomes also house the b-oxidation of the auxin precursor indole-butyric acid (IBA) to the active auxin indole-3-acetic acid (Zolman et al, 2000;Strader et al, 2010), screening for IBA resistance can yield mutants defective in peroxisome biogenesis (for review, see Bartel et al, 2014).…”

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confidence: 99%

“…Because peroxisomes are the sole site of fatty acid b-oxidation in plants (for review, see Graham, 2008), pex mutants can display reduced growth that is ameliorated by supplementation with an alternative fixed carbon source such as Suc (for review, see Bartel et al, 2014). Because peroxisomes also house the b-oxidation of the auxin precursor indole-butyric acid (IBA) to the active auxin indole-3-acetic acid (Zolman et al, 2000;Strader et al, 2010), screening for IBA resistance can yield mutants defective in peroxisome biogenesis (for review, see Bartel et al, 2014). Such mutants often are also resistant to the synthetic IBA analog 2,4-dichlorophenoxybutyric acid (2,4-DB), which is similarly b-oxidized to the auxinic herbicide 2,4-dichlorophenoxyacetic acid (Wain and Wightman, 1954;Hayashi et al, 1998).…”

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The PEX1 ATPase Stabilizes PEX6 and Plays Essential Roles in Peroxisome Biology

et al. 2017

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A variety of metabolic pathways are sequestered in peroxisomes, conserved organelles that are essential for human and plant survival. Peroxin (PEX) proteins generate and maintain peroxisomes. The PEX1 ATPase facilitates recycling of the peroxisome matrix protein receptor PEX5 and is the most commonly affected peroxin in human peroxisome biogenesis disorders. Here, we describe the isolation and characterization of, to our knowledge, the first Arabidopsis (Arabidopsis thaliana) pex1 missense alleles: pex1-2 and pex1-3. pex1-2 displayed peroxisome-related defects accompanied by reduced PEX1 and PEX6 levels. These pex1-2 defects were exacerbated by growth at high temperature and ameliorated by growth at low temperature or by PEX6 overexpression, suggesting that PEX1 enhances PEX6 stability and vice versa. pex1-3 conferred embryo lethality when homozygous, confirming that PEX1, like several other Arabidopsis peroxins, is essential for embryogenesis. pex1-3 displayed symptoms of peroxisome dysfunction when heterozygous; this semidominance is consistent with PEX1 forming a heterooligomer with PEX6 that is poisoned by pex1-3 subunits. Blocking autophagy partially rescued PEX1/pex1-3 defects, including the restoration of normal peroxisome size, suggesting that increasing peroxisome abundance can compensate for the deficiencies caused by pex1-3 and that the enlarged peroxisomes visible in PEX1/pex1-3 may represent autophagy intermediates. Overexpressing PEX1 in wild-type plants impaired growth, suggesting that excessive PEX1 can be detrimental. Our genetic, molecular, and physiological data support the heterohexamer model of PEX1-PEX6 function in plants.

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A PEX5 missense allele preferentially disrupts PTS1 cargo import into Arabidopsis peroxisomes

et al. 2019

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The sorting of eukaryotic proteins to various organellar destinations requires receptors that recognize cargo protein targeting signals and facilitate transport into the organelle. One such receptor is the peroxin PEX 5, which recruits cytosolic cargo carrying a peroxisome‐targeting signal ( PTS ) type 1 ( PTS 1) for delivery into the peroxisomal lumen (matrix). In plants and mammals, PEX 5 is also indirectly required for peroxisomal import of proteins carrying a PTS 2 signal because PEX 5 binds the PTS 2 receptor, bringing the associated PTS 2 cargo to the peroxisome along with PTS 1 cargo. Despite PEX 5 being the PTS 1 cargo receptor, previously identified Arabidopsis pex5 mutants display either impairment of both PTS 1 and PTS 2 import or defects only in PTS 2 import. Here, we report the first Arabidopsis pex5 mutant with an exclusive PTS 1 import defect. In addition to markedly diminished GFP ‐ PTS 1 import and decreased pex5‐2 protein accumulation, this pex5‐2 mutant shows typical peroxisome‐related defects, including inefficient β‐oxidation and reduced growth. Growth at reduced or elevated temperatures ameliorated or exacerbated pex5‐2 peroxisome‐related defects, respectively, without markedly changing pex5‐2 protein levels. In contrast to the diminished PTS 1 import, PTS 2 processing was only slightly impaired and PTS 2‐ GFP import appeared normal in pex5‐2 . This finding suggests that even minor peroxisomal localization of the PTS 1 protein DEG 15, the PTS 2‐processing protease, is sufficient to maintain robust PTS 2 processing.

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Protein Transport In and Out of Plant Peroxisomes

Cited by 10 publications

References 94 publications

Peroxisomal Ubiquitin-Protein Ligases Peroxin2 and Peroxin10 Have Distinct But Synergistic Roles in Matrix Protein Import and Peroxin5 Retrotranslocation in Arabidopsis

Peroxisomal Ubiquitin-Protein Ligases Peroxin2 and Peroxin10 Have Distinct But Synergistic Roles in Matrix Protein Import and Peroxin5 Retrotranslocation in Arabidopsis

The PEX1 ATPase Stabilizes PEX6 and Plays Essential Roles in Peroxisome Biology

A PEX5 missense allele preferentially disrupts PTS1 cargo import into Arabidopsis peroxisomes

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