Distinct features of multivesicular body-lysosome fusion revealed by a new cell-free content-mixing assay

When marked for degradation, surface receptor and transporter proteins are internalized and delivered to endosomes where they are packaged into intralumenal vesicles (ILVs). Many rounds of ILV formation create multivesicular bodies (MVBs) that fuse with lysosomes exposing ILVs to hydrolases for cata...

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Veröffentlicht in:bioRxiv
Hauptverfasser: Mahmoud Abdul Karim, Samyn, Dieter Ronny, Mattie, Sevan, Christopher Leonard Brett
Format: Paper
Sprache:Englisch
Veröffentlicht: Cold Spring Harbor Cold Spring Harbor Laboratory Press 27.10.2017
Cold Spring Harbor Laboratory
Ausgabe:1.2
Schlagworte:
Cell Biology
Cell fusion
Endosomes
Fusion protein
Lysosomes
SNAP receptors
Rab7
vacuole
ESCRT
Rab-GTPase
Pep12
SNARE
membrane fusion
Ypt7
Rab conversion
syntaxin
multivesicular body
MVB
endocytosis
lysosome
ISSN:2692-8205, 2692-8205
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Zusammenfassung:When marked for degradation, surface receptor and transporter proteins are internalized and delivered to endosomes where they are packaged into intralumenal vesicles (ILVs). Many rounds of ILV formation create multivesicular bodies (MVBs) that fuse with lysosomes exposing ILVs to hydrolases for catabolism. Despite being critical for protein degradation, the molecular underpinnings of MVB-lysosome fusion remain unclear, although machinery underlying other lysosome fusion events is implicated. But how then is specificity conferred? And how is MVB maturation and fusion coordinated for efficient protein degradation? To address these questions, we developed a cell-free MVB-lysosome fusion assay using S. cerevisiae as a model. After confirming that the Rab7 ortholog Ypt7 and the multisubunit tethering complex HOPS are required, we found that the Qa-SNARE Pep12 distinguishes this event from homotypic lysosome fusion. Mutations that impair MVB maturation block fusion by preventing Ypt7 activation, confirming that a Rab-cascade mechanism harmonizes MVB maturation with lysosome fusion.
Bibliographie:SourceType-Working Papers-1
ObjectType-Working Paper/Pre-Print-1
content type line 50
ISSN:2692-8205
2692-8205
DOI:10.1101/133074