Protein translocation machineries: How organelles bring in matrix proteins

Gunkel, Katja; Veenhuis, Marten; Klei, Ida J. van der

doi:10.1016/j.femsyr.2005.03.004

Cited by 6 publications

(5 citation statements)

References 55 publications

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“…The first, which remains undisputed and is of major importance to understand the mechanism of the PIM, was that newly synthesized peroxisomal proteins do not have to be unfolded to be translocated across the organelle membrane . The second was that most if not all peroxisomal proteins are imported into the organelle only after oligomerization in the cytosol , a generalization that is probably incorrect. Indeed, a growing number of observations suggest that many peroxisomal matrix proteins that are oligomeric in their native state actually arrive at the organelle matrix as monomers (reviewed in ).…”

Section: Pex5 As a Holdase‐like Proteinmentioning

confidence: 99%

“…One of the most remarkable properties of the PIM is its capacity to accept already oligomerized proteins as substrates (reviewed in ). Indeed, several studies have shown that when two interacting proteins are co‐expressed in the same cell, the existence of a PTS in one of those proteins is sufficient to ensure a peroxisomal localization for at least a fraction of the other protein .…”

Section: Pex5 As a Holdase‐like Proteinmentioning

confidence: 99%

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Protein transport into peroxisomes: Knowns and unknowns

et al. 2017

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Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and rapidly transported into the organelle by a complex machinery. The data gathered in recent years suggest that this machinery operates through a syringe-like mechanism, in which the shuttling receptor PEX5 - the "plunger" - pushes a newly synthesized protein all the way through a peroxisomal transmembrane protein complex - the "barrel" - into the matrix of the organelle. Notably, insertion of cargo-loaded receptor into the "barrel" is an ATP-independent process, whereas extraction of the receptor back into the cytosol requires its monoubiquitination and the action of ATP-dependent mechanoenzymes. Here, we review the main data behind this model.

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Section: Pex5 As a Holdase‐like Proteinmentioning

confidence: 99%

Section: Pex5 As a Holdase‐like Proteinmentioning

confidence: 99%

Protein transport into peroxisomes: Knowns and unknowns

et al. 2017

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“…Our current knowledge on oligomeric protein import into peroxisomes suggests that most of the peroxisomal matrix proteins assemble in the cytosol to mature to enzymatically active proteins prior to import [75,76]. Most likely, AO is an exception to this rule.…”

Section: Assembly Of Aomentioning

confidence: 99%

Alcohol oxidase: A complex peroxisomal, oligomeric flavoprotein

Ozimek

Veenhuis

Klei

2005

FEMS Yeast Research

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Alcohol oxidase (AO) is the key enzyme of methanol metabolism in methylotrophic yeast species. It catalyses the first step of methanol catabolism, namely its oxidation to formaldehyde with concomitant production of hydrogen peroxide. In its mature active form, AO is a molecule of high molecular mass (600 kDa) that consists of eight identical subunits, each of which carry one non-covalently bound flavin adenine nucleotide (FAD) molecule as the prosthetic group. In vivo, the protein is compartmentalized into special cell organelles, termed peroxisomes. AO is an abundant protein and its synthesis is strictly regulated by repression/derepression and induction mechanisms that occur at the transcriptional level. Various aspects of its sorting and assembly/activation render AO a unique protein. Recent developments of AO synthesis, sorting and assembly/activation are highlighted in this paper.

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“…The data supporting this idea are abundant and include (i) several studies showing that when two interacting proteins are expressed in the same cell, the presence of a single PTS in one of those proteins is sufficient to ensure targeting of at least a fraction of the other protein to the peroxisome [38][39][40][41][42][43][44] and (ii) pulse-chase analyses on yeasts suggesting that two peroxisomal matrix enzymes oligomerize in the cytosol prior to import [45,46]. Collectively, these data led to the generalization that most peroxisomal proteins oligomerize in the cytosol before import, a concept that can be found in many reviews and even in academic textbooks [15,[47][48][49][50][51]. However, it should be noted that all of the above cited studies focused on proteins that were overexpressed, either through the use of recombinant genes having strong promoters or, in the case of yeasts/fungi, by simply growing these organisms in special media that induce a dramatic proliferation of peroxisomes.…”

Section: Introductionmentioning

confidence: 99%

The peroxisomal protein import machinery displays a preference for monomeric substrates

et al. 2015

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Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and transported by the shuttling receptor PEX5 to the peroxisomal membrane docking/translocation machinery, where they are translocated into the organelle matrix. Under certain experimental conditions this protein import machinery has the remarkable capacity to accept already oligomerized proteins, a property that has heavily influenced current models on the mechanism of peroxisomal protein import. However, whether or not oligomeric proteins are really the best and most frequent clients of this machinery remain unclear. In this work, we present three lines of evidence suggesting that the peroxisomal import machinery displays a preference for monomeric proteins. First, in agreement with previous findings on catalase, we show that PEX5 binds newly synthesized (monomeric) acyl-CoA oxidase 1 (ACOX1) and urate oxidase (UOX), potently inhibiting their oligomerization. Second, in vitro import experiments suggest that monomeric ACOX1 and UOX are better peroxisomal import substrates than the corresponding oligomeric forms. Finally, we provide data strongly suggesting that although ACOX1 lacking a peroxisomal targeting signal can be imported into peroxisomes when co-expressed with ACOX1 containing its targeting signal, this import pathway is inefficient.

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Protein translocation machineries: How organelles bring in matrix proteins

Cited by 6 publications

References 55 publications

Protein transport into peroxisomes: Knowns and unknowns

Protein transport into peroxisomes: Knowns and unknowns

Alcohol oxidase: A complex peroxisomal, oligomeric flavoprotein

The peroxisomal protein import machinery displays a preference for monomeric substrates

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