Artificial import substrates reveal an omnivorous peroxisomal importomer

Yang, Jing; Pieuchot, Laurent; Jedd, Gregory

doi:10.1111/tra.12607

Cited by 12 publications

(12 citation statements)

References 56 publications

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“…Furthermore, we detected targeting of GFP-Mfe2 and PTS2-GFP to peroxisomes upon expression of the Pex5b NTD in the absence of the full-length protein ( Figure 5 ). The capability of the peroxisomal import machinery to translocate large oligomeric cargo has been described ( Walton et al, 1995 ; Yang et al, 2018 ). It will be interesting to establish how interactions at different sites of Pex5 proteins influence import of bigger complexes and import kinetics.…”

Section: Discussionmentioning

confidence: 99%

Two Pex5 Proteins With Different Cargo Specificity Are Critical for Peroxisome Function in Ustilago maydis

Ast

Bäcker

Bittner

et al. 2022

Front. Cell Dev. Biol.

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Peroxisomes are dynamic multipurpose organelles with a major function in fatty acid oxidation and breakdown of hydrogen peroxide. Many proteins destined for the peroxisomal matrix contain a C-terminal peroxisomal targeting signal type 1 (PTS1), which is recognized by tetratricopeptide repeat (TPR) proteins of the Pex5 family. Various species express at least two different Pex5 proteins, but how this contributes to protein import and organelle function is not fully understood. Here, we analyzed truncated and chimeric variants of two Pex5 proteins, Pex5a and Pex5b, from the fungus Ustilago maydis. Both proteins are required for optimal growth on oleic acid-containing medium. The N-terminal domain (NTD) of Pex5b is critical for import of all investigated peroxisomal matrix proteins including PTS2 proteins and at least one protein without a canonical PTS. In contrast, the NTD of Pex5a is not sufficient for translocation of peroxisomal matrix proteins. In the presence of Pex5b, however, specific cargo can be imported via this domain of Pex5a. The TPR domains of Pex5a and Pex5b differ in their affinity to variations of the PTS1 motif and thus can mediate import of different subsets of matrix proteins. Together, our data reveal that U. maydis employs versatile targeting modules to control peroxisome function. These findings will promote our understanding of peroxisomal protein import also in other biological systems.

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Section: Discussionmentioning

confidence: 99%

Two Pex5 Proteins With Different Cargo Specificity Are Critical for Peroxisome Function in Ustilago maydis

Ast

Bäcker

Bittner

et al. 2022

Front. Cell Dev. Biol.

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“…There are no indications for its synthesis in these organelles. It is probably "piggyback" imported in association with the positively charged matrix proteins through the transient pores formed by peroxins which have the ability to transport proteins, even when folded, in multimeric form or with bound, large artificial ligands (Häusler et al, 1996;Meinecke et al, 2010;Yang et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Lipids for growing and proliferating peroxisomes are provided by the vesicular transport from the ER, but may also be delivered via not yet wellstudied non-vesicular routes involving contact sites between the organelles and the ER (Jansen and Van der Klei, 2019). The import of peroxisomal and glycosomal matrix proteins can occur by translocation of fully folded proteins and even multimeric complexes (Yang et al, 2018). This process starts in the cytosol by recognition of a peroxisomal-targeting signal (PTS), in most cases either a sequence motif at the C-terminus (PTS1) or one near the N-terminus (PTS2), in newly synthesized proteins by either of two cytosolic receptors of the peroxin family.…”

Section: Biogenesis Of Glycosomesmentioning

confidence: 99%

Structure, Properties, and Function of Glycosomes in Trypanosoma cruzi

Quiñones

Acosta

Gonçalves

et al. 2020

Front. Cell. Infect. Microbiol.

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Glycosomes are peroxisome-related organelles that have been identified in kinetoplastids and diplonemids. The hallmark of glycosomes is their harboring of the majority of the glycolytic enzymes. Our biochemical studies and proteome analysis of Trypanosoma cruzi glycosomes have located, in addition to enzymes of the glycolytic pathway, enzymes of several other metabolic processes in the organelles. These analyses revealed many aspects in common with glycosomes from other trypanosomatids as well as features that seem specific for T. cruzi. Their enzyme content indicates that T. cruzi glycosomes are multifunctional organelles, involved in both several catabolic processes such as glycolysis and anabolic ones. Specifically discussed in this minireview are the cross-talk between glycosomal metabolism and metabolic processes occurring in other cell compartments, and the importance of metabolite translocation systems in the glycosomal membrane to enable the coordination between the spatially separated processes. Possible mechanisms for metabolite translocation across the membrane are suggested by proteins identified in the organelle's membrane-homologs of the ABC and MCF transporter families-and the presence of channels as inferred previously from the detection of channel-forming proteins in glycosomal membrane preparations from the related parasite T. brucei. Together, these data provide insight in the way in which different parts of T. cruzi metabolism, although uniquely distributed over different compartments, are integrated and regulated. Moreover, this information reveals opportunities for the development of drugs against Chagas disease caused by these parasites and for which currently no adequate treatment is available.

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“…Interestingly, weak protein-protein interactions are sufficient to support piggyback import. Indeed, blue native gels failed to show interaction between the mammalian SOD and CCS partners (24) and synthetic substrates designed to evaluate the import of proteins showed dissociation constants (K d ) differing over three orders of magnitude, with even an apparent K d of ∼6×10 −3 M allowing the detection of piggyback import (52). Despite several attempts, we did not observe any interaction between UGP and PEPCK using co-immunoprecipitation or native gels, suggesting that these interactions are weak and transient.…”

Section: Discussionmentioning

confidence: 99%

The trypanosome UDP-glucose pyrophosphorylase is imported by piggybacking into glycosomes where unconventional sugar nucleotide synthesis takes place

Villafraz

Baudouin

Mazet

et al. 2021

Preprint

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Glycosomes are peroxisome-related organelles of trypanosomatid parasites containing metabolic pathways usually present in the cytosol of other eukaryotes, such as glycolysis and biosynthesis of sugar nucleotides. UDP-glucose pyrophosphorylase (UGP), the enzyme responsible for the synthesis of the sugar nucleotide UDP-glucose, is localised in the cytosol and glycosomes of the bloodstream and procyclic trypanosomes, despite the absence of any known peroxisomal targeting signal (PTS1 and PTS2). The questions we addressed here are (i) is the unusual glycosomal biosynthetic pathway of sugar nucleotide functional and (ii) how the PTS-free UGP is imported into glycosomes? We showed that UGP is imported into glycosomes by piggybacking on the glycosomal PTS1-containing phosphoenolpyruvate carboxykinase (PEPCK) and identified the domains involved in the UGP/PEPCK interaction. Proximity ligation assays revealed that this interaction occurs in 3-10% of glycosomes, suggesting that these correspond to organelles competent for protein import. We also showed that UGP is essential for growth of trypanosomes and that both the glycosomal and cytosolic metabolic pathways involving UGP are functional, since the lethality of the knock-down UGP mutant cell line (RNAiUGP) was rescued by expressing a recoded UGP in the organelle (RNAiUGP/EXPrUGP-GPDH). Our conclusion was supported by targeted metabolomic analyses (IC-HRMS) showing that UDP-glucose is no longer detectable in the RNAiUGP mutant, while it is still produced in cells expressing UGP exclusively in the cytosol (PEPCK null mutant) or glycosomes (RNAiUGP/EXPrUGP-GPDH). Trypanosomatids are the only known organisms to have selected functional peroxisomal (glycosomal) sugar nucleotide biosynthetic pathways in addition to the canonical cytosolic ones.

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Artificial import substrates reveal an omnivorous peroxisomal importomer

Cited by 12 publications

References 56 publications

Two Pex5 Proteins With Different Cargo Specificity Are Critical for Peroxisome Function in Ustilago maydis

Two Pex5 Proteins With Different Cargo Specificity Are Critical for Peroxisome Function in Ustilago maydis

Structure, Properties, and Function of Glycosomes in Trypanosoma cruzi

The trypanosome UDP-glucose pyrophosphorylase is imported by piggybacking into glycosomes where unconventional sugar nucleotide synthesis takes place

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