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Vps27 recruits ESCRT machinery to endosomes during MVB sorting.

Katzmann DJ, Stefan CJ, Babst M, Emr SD - J. Cell Biol. (2003)

Bottom Line: A peptide sequence in this domain, PTVP, is involved in the function of Vps27 in the MVB pathway, the efficient endosomal recruitment of ESCRT-I, and is related to a motif in HIV-1 Gag protein that is capable of interacting with Tsg101, the mammalian homologue of Vps23.We propose that compartmental specificity for the MVB sorting reaction is the result of interactions of Vps27 with phosphatidylinositol 3-phosphate and ubiquitin.Vps27 subsequently recruits/activates ESCRT-I on endosomes, thereby facilitating sorting of ubiquitinated MVB cargoes.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular and Molecular Medicine, and Howard Hughes Medical Institute, University of California, San Diego School of Medicine, La Jolla, CA 92093-0688, USA.

ABSTRACT
Down-regulation (degradation) of cell surface proteins within the lysosomal lumen depends on the function of the multivesicular body (MVB) sorting pathway. The function of this pathway requires the class E vacuolar protein sorting (Vps) proteins. Of the class E Vps proteins, both the ESCRT-I complex (composed of the class E proteins Vps23, 28, and 37) and Vps27 (mammalian hepatocyte receptor tyrosine kinase substrate, Hrs) have been shown to interact with ubiquitin, a signal for entry into the MVB pathway. We demonstrate that activation of the MVB sorting reaction is dictated largely through interactions between Vps27 and the endosomally enriched lipid species phosphatidylinositol 3-phosphate via the FYVE domain (Fab1, YGL023, Vps27, and EEA1) of Vps27. ESCRT-I then physically binds to Vps27 on endosomal membranes via a domain within the COOH terminus of Vps27. A peptide sequence in this domain, PTVP, is involved in the function of Vps27 in the MVB pathway, the efficient endosomal recruitment of ESCRT-I, and is related to a motif in HIV-1 Gag protein that is capable of interacting with Tsg101, the mammalian homologue of Vps23. We propose that compartmental specificity for the MVB sorting reaction is the result of interactions of Vps27 with phosphatidylinositol 3-phosphate and ubiquitin. Vps27 subsequently recruits/activates ESCRT-I on endosomes, thereby facilitating sorting of ubiquitinated MVB cargoes.

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Identification of a region in Vps27 involved in the efficient recruitment of ESCRT-I to endosomes. Localization of Vps23-GFP in vps27Δ cells (MBY21; left column) or vps4Δ vps27Δ cells (DKY79; right column) expressing either wild-type or indicated mutant forms of Vps27 from a plasmid was observed by fluorescence and Normarski microscopy.
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fig5: Identification of a region in Vps27 involved in the efficient recruitment of ESCRT-I to endosomes. Localization of Vps23-GFP in vps27Δ cells (MBY21; left column) or vps4Δ vps27Δ cells (DKY79; right column) expressing either wild-type or indicated mutant forms of Vps27 from a plasmid was observed by fluorescence and Normarski microscopy.

Mentions: These interaction studies revealed that association of Vps27 and ESCRT-I did not require Vps27 NH2-terminal VHS and UIM domains, suggesting that COOH-terminal residues within Vps27 may be involved in this interaction. Accordingly, we constructed a series of deletions in the COOH-terminal domain of Vps27 and examined Vps23-GFP localization in vps27Δ mutant cells expressing various forms of Vps27 from a low copy plasmid. Truncation of Vps27 at residue 581 (Vps27Δ581–622) conferred a defect in Vps23-GFP localization, as Vps23-GFP was no longer efficiently recruited to punctate compartments but was mainly diffuse throughout the cytoplasm in vps27Δ580–622 mutant cells (Fig. 5, left column). In contrast, deletion of Vps27 residues 619–622 that comprise a candidate clathrin-binding motif had no effect on Vps23-GFP localization (unpublished data), suggesting that residues 581 to 618 in Vps27 control ESCRT-I localization.


Vps27 recruits ESCRT machinery to endosomes during MVB sorting.

Katzmann DJ, Stefan CJ, Babst M, Emr SD - J. Cell Biol. (2003)

Identification of a region in Vps27 involved in the efficient recruitment of ESCRT-I to endosomes. Localization of Vps23-GFP in vps27Δ cells (MBY21; left column) or vps4Δ vps27Δ cells (DKY79; right column) expressing either wild-type or indicated mutant forms of Vps27 from a plasmid was observed by fluorescence and Normarski microscopy.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172707&req=5

fig5: Identification of a region in Vps27 involved in the efficient recruitment of ESCRT-I to endosomes. Localization of Vps23-GFP in vps27Δ cells (MBY21; left column) or vps4Δ vps27Δ cells (DKY79; right column) expressing either wild-type or indicated mutant forms of Vps27 from a plasmid was observed by fluorescence and Normarski microscopy.
Mentions: These interaction studies revealed that association of Vps27 and ESCRT-I did not require Vps27 NH2-terminal VHS and UIM domains, suggesting that COOH-terminal residues within Vps27 may be involved in this interaction. Accordingly, we constructed a series of deletions in the COOH-terminal domain of Vps27 and examined Vps23-GFP localization in vps27Δ mutant cells expressing various forms of Vps27 from a low copy plasmid. Truncation of Vps27 at residue 581 (Vps27Δ581–622) conferred a defect in Vps23-GFP localization, as Vps23-GFP was no longer efficiently recruited to punctate compartments but was mainly diffuse throughout the cytoplasm in vps27Δ580–622 mutant cells (Fig. 5, left column). In contrast, deletion of Vps27 residues 619–622 that comprise a candidate clathrin-binding motif had no effect on Vps23-GFP localization (unpublished data), suggesting that residues 581 to 618 in Vps27 control ESCRT-I localization.

Bottom Line: A peptide sequence in this domain, PTVP, is involved in the function of Vps27 in the MVB pathway, the efficient endosomal recruitment of ESCRT-I, and is related to a motif in HIV-1 Gag protein that is capable of interacting with Tsg101, the mammalian homologue of Vps23.We propose that compartmental specificity for the MVB sorting reaction is the result of interactions of Vps27 with phosphatidylinositol 3-phosphate and ubiquitin.Vps27 subsequently recruits/activates ESCRT-I on endosomes, thereby facilitating sorting of ubiquitinated MVB cargoes.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular and Molecular Medicine, and Howard Hughes Medical Institute, University of California, San Diego School of Medicine, La Jolla, CA 92093-0688, USA.

ABSTRACT
Down-regulation (degradation) of cell surface proteins within the lysosomal lumen depends on the function of the multivesicular body (MVB) sorting pathway. The function of this pathway requires the class E vacuolar protein sorting (Vps) proteins. Of the class E Vps proteins, both the ESCRT-I complex (composed of the class E proteins Vps23, 28, and 37) and Vps27 (mammalian hepatocyte receptor tyrosine kinase substrate, Hrs) have been shown to interact with ubiquitin, a signal for entry into the MVB pathway. We demonstrate that activation of the MVB sorting reaction is dictated largely through interactions between Vps27 and the endosomally enriched lipid species phosphatidylinositol 3-phosphate via the FYVE domain (Fab1, YGL023, Vps27, and EEA1) of Vps27. ESCRT-I then physically binds to Vps27 on endosomal membranes via a domain within the COOH terminus of Vps27. A peptide sequence in this domain, PTVP, is involved in the function of Vps27 in the MVB pathway, the efficient endosomal recruitment of ESCRT-I, and is related to a motif in HIV-1 Gag protein that is capable of interacting with Tsg101, the mammalian homologue of Vps23. We propose that compartmental specificity for the MVB sorting reaction is the result of interactions of Vps27 with phosphatidylinositol 3-phosphate and ubiquitin. Vps27 subsequently recruits/activates ESCRT-I on endosomes, thereby facilitating sorting of ubiquitinated MVB cargoes.

Show MeSH