The Functional Specialization of Exomer as a Cargo Adaptor During the Evolution of Fungi

Anton, Carlos; Taubas, Javier Valdez; Roncero, César

doi:10.1534/genetics.118.300767

Cited by 10 publications

(21 citation statements)

References 61 publications

(13 reference statements)

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“…Notably, in S. cerevisiae, there are two forms of AP-1 that share the same large (Apl2 and Apl4) and small (Aps1) subunits, but distinct medium subunits (Apm1 or Apm2) that seem to confer differential cargo recognition and sorting (Valdivia et al 2002;Renard et al 2010;Whitfield et al 2016). Additionally, in fission yeast, the AP-1 complex seems to co-operate with the exomer, a nonessential, fungal-specific heterotetrameric complex assembled at the trans-Golgi network, for the delivery of a distinct set of proteins to the plasma membrane (Hoya et al 2017;Anton et al 2018).…”

Section: Discussionmentioning

confidence: 99%

Secretory Vesicle Polar Sorting, Endosome Recycling and Cytoskeleton Organization Require the AP-1 Complex in Aspergillus nidulans

2018

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The AP-1 complex is essential for membrane protein traffic via its role in the pinching-off and sorting of secretory vesicles (SVs) from the -Golgi and/or endosomes. While its essentiality is undisputed in metazoa, its role in simpler eukaryotes seems less clear. Here, we dissect the role of AP-1 in the filamentous fungus and show that it is absolutely essential for growth due to its role in clathrin-dependent maintenance of polar traffic of specific membrane cargoes toward the apex of growing hyphae. We provide evidence that AP-1 is involved in both anterograde sorting of RabE-labeled SVs and RabA/B-dependent endosome recycling. Additionally, AP-1 is shown to be critical for microtubule and septin organization, further rationalizing its essentiality in cells that face the challenge of cytoskeleton-dependent polarized cargo traffic. This work also opens a novel issue on how nonpolar cargoes, such as transporters, are sorted to the eukaryotic plasma membrane.

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Section: Discussionmentioning

confidence: 99%

Secretory Vesicle Polar Sorting, Endosome Recycling and Cytoskeleton Organization Require the AP-1 Complex in Aspergillus nidulans

2018

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“…Notably, in S. cerevisiae , there are two forms of AP-1 which share the same large (Apl2 and Apl4) and small (Aps1) subunits, but distinct medium subunits (Apm1 or Apm2) that seem to confer differential cargo recognition and sorting (Valdivia et al, 2002; Renard et al, 2010; Whitfield et al, 2016). Additionally, in yeast, the AP-1 complex seems to co-operate with the exomer, a non-essential, fungal-specific heterotetrameric complex assembled at the trans-Golgi network, for the delivery of a distinct set of proteins to the plasma membrane (Hoya et al, 2017; Anton et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Apart from the COPI and COPII vesicle coat adaptors that mediate traffic between the ER and the early Golgi compartment (Lee et al, 2004; Zanetti et al, 2011), of particular importance are the heterotetrameric AP (formally named after Assembly Polypeptide and later as Adaptor Protein) complexes, comprising of two large subunits (also called adaptins; β-adaptin and γ- or α-adaptin), together with a medium-sized (μ) and a small (σ) subunit (Robinson 2004; 2015). Other adaptors, some of which display similarity to AP subunits, like the GGAs, epsin-related proteins, or components of the exomer and retromer complexes are also critical for the sorting of specific cargoes (Bonifacino 2004; 2014; Robinson 2015; Spang 2015; Anton et al, 2018). Importantly, the various cargo sorting routes are often overlapping and might share common adaptors (Hoya et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

The AP-1 complex is essential for fungal growth via its role in secretory vesicle polar sorting, endosomal recycling and cytoskeleton organization

Μαρτζούκου¹,

Diallinas²,

Amillis³

2018

Preprint

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The AP-1 complex is essential for membrane protein traffic via its role in the pinching-off and sorting of secretory vesicles from the trans-Golgi and/or endosomes. While its essentiality is undisputed in metazoa, its role in model simpler eukaryotes seems less clear. Here we dissect the role of AP-1 in the filamentous fungus Aspergillus nidulans and show that it is absolutely essential for growth due to its role in clathrin-dependent maintenance of polar traffic of specific membrane cargoes towards the apex of growing hyphae. We provide evidence that AP-1 is involved in both anterograde sorting of RabERab11-labeled secretory vesicles and RabA/BRab5- dependent endosome recycling. Additionally, AP-1 is shown to be critical for microtubule and septin organization, further rationalizing its essentiality in cells that face the challenge of cytoskeleton-dependent polarized cargo traffic. This work also opens a novel issue on how non-polar cargoes, such as transporters, are sorted to the eukaryotic plasma membrane.

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“…17,21,24 However, our recent work, based on the evolutionary characterization of exomer function across the fungi kingdom, suggests that exomer may have additional functions. 29 More importantly, S. cerevisiae exomer mutants showed multiple phenotypes that cannot be explained by known cargoes of exomer such as sensitivity to ammonium. 21,29 In an effort to better understand the functionality of exomer, we first confirmed the ammonium sensitivity of the exomer mutant chs5∆ by showing that this mutant grew poorly in YEPD supplemented with 0.2 mol/L ammonium (Figure 1A).…”

Section: Exomer Mutants Show Ammonium Sensitivity Due To the Reduced Uptake Of Tryptophanmentioning

confidence: 99%

Exomer complex regulates protein traffic at the TGN through differential interactions with cargos and clathrin adaptor complexes

et al. 2021

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Protein sorting at the trans-Golgi network (TGN) usually requires the assistance of cargo adaptors. However, it remains to be examined how the same complex can mediate both the export and retention of different proteins or how sorting complexes interact among themselves. In Saccharomyces cerevisiae, the exomer complex is involved in the polarized transport of some proteins from the TGN to the plasma membrane (PM). Intriguingly, exomer and its cargos also show a sort of functional relationship with TGN clathrin adaptors that is still unsolved. Here, using a wide range of techniques, including time-lapse and BIFC microscopy, we describe new molecular implications of the exomer complex in protein sorting and address its different layers of functional interaction with clathrin adaptor complexes. Exomer mutants show impaired amino acid uptake because it facilitates not only the polarized delivery of amino acid permeases to the PM but also participates in their endosomal traffic. We propose a model for exomer where it modulates the recruitment of TGN clathrin adaptors directly or indirectly through the Arf1 function. Moreover, we describe an in vivo competitive relationship between the exomer and AP-1 complexes for the model cargo Chs3. These results highlight a broad role for exomer in 2 of 26 | ANTON-PLAGARO eT AL.

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The Functional Specialization of Exomer as a Cargo Adaptor During the Evolution of Fungi

Cited by 10 publications

References 61 publications

Secretory Vesicle Polar Sorting, Endosome Recycling and Cytoskeleton Organization Require the AP-1 Complex in Aspergillus nidulans

Secretory Vesicle Polar Sorting, Endosome Recycling and Cytoskeleton Organization Require the AP-1 Complex in Aspergillus nidulans

The AP-1 complex is essential for fungal growth via its role in secretory vesicle polar sorting, endosomal recycling and cytoskeleton organization

Exomer complex regulates protein traffic at the TGN through differential interactions with cargos and clathrin adaptor complexes

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