Retromer-driven membrane tubulation separates endosomal recycling from Rab7/Ypt7-dependent fusion

Endosomes are the major protein-sorting hubs of the endocytic pathway. They sort proteins destined for degradation into internal vesicles while in parallel recycling receptors via tubular carriers back to the Golgi. Tubule formation depends on the Rab7/Ypt7-interacting retromer complex, consisting o...

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Bibliographic Details
Published in:Molecular biology of the cell 2017-03, Vol.28 (6), p.783-791
Main Authors: Purushothaman, Latha Kallur, Arlt, Henning, Kuhlee, Anne, Raunser, Stefan, Ungermann, Christian
Format: Article
Language:English
Subjects:
Biological Transport
Endosomes - metabolism
Endosomes - physiology
Golgi Apparatus - metabolism
Lysosomes - metabolism
Protein Transport - physiology
rab GTP-Binding Proteins - metabolism
rab GTP-Binding Proteins - physiology
Saccharomyces cerevisiae - metabolism
Saccharomyces cerevisiae Proteins - metabolism
Sorting Nexins - metabolism
Vacuoles - metabolism
Vesicular Transport Proteins - metabolism
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Summary:Endosomes are the major protein-sorting hubs of the endocytic pathway. They sort proteins destined for degradation into internal vesicles while in parallel recycling receptors via tubular carriers back to the Golgi. Tubule formation depends on the Rab7/Ypt7-interacting retromer complex, consisting of the sorting nexin dimer (SNX-BAR) and the trimeric cargo selection complex (CSC). Fusion of mature endosomes with the lysosome-like vacuole also requires Rab7/Ypt7. Here we solve a major problem in understanding this dual function of endosomal Rab7/Ypt7, using a fully reconstituted system, including purified, full-length yeast SNX-BAR and CSC, whose overall structure we present. We reveal that the membrane-active SNX-BAR complex displaces Ypt7 from cargo-bound CSC during formation of recycling tubules. This explains how a single Rab can coordinate recycling and fusion on endosomes.
ISSN:1059-1524
1939-4586
DOI:10.1091/mbc.E16-08-0582