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  1. Article ; Online: Yeast vacuole fusion: a model system for eukaryotic endomembrane dynamics.

    Ostrowicz, Clemens W / Meiringer, Christoph T A / Ungermann, Christian

    Autophagy

    2007  Volume 4, Issue 1, Page(s) 5–19

    Abstract: Vesicular transport in eukaryotic cells is concluded with the consumption of the vesicle at the target membrane. This fusion process relies on Rabs, tethers and SNAREs. Powerful in vitro fusion systems using isolated organelles were crucial to obtain ... ...

    Abstract Vesicular transport in eukaryotic cells is concluded with the consumption of the vesicle at the target membrane. This fusion process relies on Rabs, tethers and SNAREs. Powerful in vitro fusion systems using isolated organelles were crucial to obtain insights into the underlying mechanism of membrane fusion- from the initiation of fusion to lipid bilayer mixing. Among these systems, yeast vacuoles turned out to be particularly useful as they can be manipulated biochemically and genetically. Studies relying on this organelle have revealed insights into the connection of vacuole fusion to endomembrane biogenesis. A number of fusion factors were identified and characterized over the last several years, and placed into the fusion cascade. Within this review, we will present and discuss the current state of our knowledge on vacuole fusion.
    MeSH term(s) Endosomes/metabolism ; Golgi Apparatus/metabolism ; Intracellular Membranes/metabolism ; Membrane Fusion/physiology ; Membrane Lipids/metabolism ; SNARE Proteins/metabolism ; Saccharomyces cerevisiae/cytology ; Saccharomyces cerevisiae Proteins/metabolism ; Vacuoles/metabolism ; trans-Golgi Network/metabolism
    Chemical Substances Membrane Lipids ; SNARE Proteins ; Saccharomyces cerevisiae Proteins
    Language English
    Publishing date 2007-09-12
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2454135-7
    ISSN 1554-8635 ; 1554-8627
    ISSN (online) 1554-8635
    ISSN 1554-8627
    DOI 10.4161/auto.5054
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Vps41 phosphorylation and the Rab Ypt7 control the targeting of the HOPS complex to endosome-vacuole fusion sites.

    Cabrera, Margarita / Ostrowicz, Clemens W / Mari, Muriel / LaGrassa, Tracy J / Reggiori, Fulvio / Ungermann, Christian

    Molecular biology of the cell

    2009  Volume 20, Issue 7, Page(s) 1937–1948

    Abstract: Membrane fusion depends on multisubunit tethering factors such as the vacuolar HOPS complex. We previously showed that the vacuolar casein kinase Yck3 regulates vacuole biogenesis via phosphorylation of the HOPS subunit Vps41. Here, we link the ... ...

    Abstract Membrane fusion depends on multisubunit tethering factors such as the vacuolar HOPS complex. We previously showed that the vacuolar casein kinase Yck3 regulates vacuole biogenesis via phosphorylation of the HOPS subunit Vps41. Here, we link the identified Vps41 phosphorylation site to HOPS function at the endosome-vacuole fusion site. The nonphosphorylated Vps41 mutant (Vps41 S-A) accumulates together with other HOPS subunits on punctate structures proximal to the vacuole that expand in a class E mutant background and that correspond to in vivo fusion sites. Ultrastructural analysis of this mutant confirmed the presence of tubular endosomal structures close to the vacuole. In contrast, Vps41 with a phosphomimetic mutation (Vps41 S-D) is mislocalized and leads to multilobed vacuoles, indicative of a fusion defect. These two phenotypes can be rescued by overproduction of the vacuolar Rab Ypt7, revealing that both Ypt7 and Yck3-mediated phosphorylation modulate the Vps41 localization to the endosome-vacuole junction. Our data suggest that Vps41 phosphorylation fine-tunes the organization of vacuole fusion sites and provide evidence for a fusion "hot spot" on the vacuole limiting membrane.
    MeSH term(s) Adaptor Protein Complex 3/metabolism ; Amino Acid Sequence ; Casein Kinase I/metabolism ; Cell Membrane Structures/metabolism ; Cell Membrane Structures/ultrastructure ; Endosomes/metabolism ; Endosomes/ultrastructure ; GTPase-Activating Proteins/metabolism ; Membrane Fusion ; Molecular Sequence Data ; Multiprotein Complexes/metabolism ; Mutant Proteins/metabolism ; Mutation/genetics ; Phosphorylation ; Protein Transport ; Saccharomyces cerevisiae/cytology ; Saccharomyces cerevisiae/ultrastructure ; Saccharomyces cerevisiae Proteins/chemistry ; Saccharomyces cerevisiae Proteins/metabolism ; Vacuoles/metabolism ; Vacuoles/ultrastructure ; Vesicular Transport Proteins/chemistry ; Vesicular Transport Proteins/metabolism ; rab GTP-Binding Proteins/metabolism
    Chemical Substances Adaptor Protein Complex 3 ; GTPase-Activating Proteins ; Multiprotein Complexes ; Mutant Proteins ; Saccharomyces cerevisiae Proteins ; VPS41 protein, S cerevisiae ; Vesicular Transport Proteins ; Casein Kinase I (EC 2.7.11.1) ; YCK3 protein, S cerevisiae (EC 2.7.11.1) ; YPT7 protein, S cerevisiae (EC 3.6.1.-) ; rab GTP-Binding Proteins (EC 3.6.5.2)
    Language English
    Publishing date 2009-02-04
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1098979-1
    ISSN 1939-4586 ; 1059-1524
    ISSN (online) 1939-4586
    ISSN 1059-1524
    DOI 10.1091/mbc.E08-09-0943
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 2853: Show issues Location:
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    Zs.MO 410: Show issues

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  3. Article: The CORVET tethering complex interacts with the yeast Rab5 homolog Vps21 and is involved in endo-lysosomal biogenesis.

    Peplowska, Karolina / Markgraf, Daniel F / Ostrowicz, Clemens W / Bange, Gert / Ungermann, Christian

    Developmental cell

    2007  Volume 12, Issue 5, Page(s) 739–750

    Abstract: The dynamic equilibrium between vesicle fission and fusion at Golgi, endosome, and vacuole/lysosome is critical for the maintenance of organelle identity. It depends, among others, on Rab GTPases and tethering factors, whose function and regulation are ... ...

    Abstract The dynamic equilibrium between vesicle fission and fusion at Golgi, endosome, and vacuole/lysosome is critical for the maintenance of organelle identity. It depends, among others, on Rab GTPases and tethering factors, whose function and regulation are still unclear. We now show that transport among Golgi, endosome, and vacuole is controlled by two homologous tethering complexes, the previously identified HOPS complex at the vacuole and a novel endosomal tethering (CORVET) complex, which interacts with the Rab GTPase Vps21. Both complexes share the four class C Vps proteins: Vps11, Vps16, Vps18, and Vps33. The HOPS complex, in addition, contains Vps41/Vam2 and Vam6, whereas the CORVET complex has the Vps41 homolog Vps8 and the (h)Vam6 homolog Vps3. Strikingly, the CORVET and HOPS complexes can interconvert; we identify two additional intermediate complexes, both consisting of the class C core bound to Vam6-Vps8 or Vps3-Vps41. Our data suggest that modular assembled tethering complexes define organelle biogenesis in the endocytic pathway.
    MeSH term(s) Endosomes/metabolism ; Lysosomes/metabolism ; Multiprotein Complexes/metabolism ; Mutation/genetics ; Protein Binding ; Saccharomyces cerevisiae/cytology ; Saccharomyces cerevisiae/metabolism ; Saccharomyces cerevisiae Proteins/metabolism ; Sequence Homology, Amino Acid ; Vacuoles/metabolism ; Vesicular Transport Proteins/metabolism ; rab GTP-Binding Proteins/metabolism ; rab5 GTP-Binding Proteins/metabolism
    Chemical Substances Multiprotein Complexes ; Saccharomyces cerevisiae Proteins ; VPS3 protein, S cerevisiae ; VPS8 protein, S cerevisiae ; Vesicular Transport Proteins ; VPS21 protein, S cerevisiae (EC 3.6.1.-) ; rab GTP-Binding Proteins (EC 3.6.5.2) ; rab5 GTP-Binding Proteins (EC 3.6.5.2)
    Language English
    Publishing date 2007-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2054967-2
    ISSN 1878-1551 ; 1534-5807
    ISSN (online) 1878-1551
    ISSN 1534-5807
    DOI 10.1016/j.devcel.2007.03.006
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 5742: Show issues Location:
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    Zs.MG 76: Show issues

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  4. Article: Defined Subunit Arrangement and Rab Interactions Are Required for Functionality of the HOPS Tethering Complex

    Ostrowicz, Clemens W / Bröcker, Cornelia / Ahnert, Franziska / Nordmann, Mirjana / Lachmann, Jens / Peplowska, Karolina / Perz, Angela / Auffarth, Kathrin / Engelbrecht-Vandré, Siegfried / Ungermann, Christian

    Traffic. 2010 Oct., v. 11, no. 10

    2010  

    Abstract: Within the endomembrane system of eukaryotic cells, multisubunit tethering complexes together with their corresponding Rab-GTPases coordinate vesicle tethering and fusion. Here, we present evidence that two homologous hexameric tethering complexes, the ... ...

    Abstract Within the endomembrane system of eukaryotic cells, multisubunit tethering complexes together with their corresponding Rab-GTPases coordinate vesicle tethering and fusion. Here, we present evidence that two homologous hexameric tethering complexes, the endosomal CORVET (Class C core vacuole/endosome transport) and the vacuolar HOPS (homotypic vacuole fusion and protein sorting) complex, have similar subunit topologies. Both complexes contain two Rab-binding proteins at one end, and the Sec1/Munc18-like Vps33 at the opposite side, suggesting a model on membrane bridging via Rab-GTP and SNARE binding. In agreement, HOPS activity can be reconstituted using purified subcomplexes containing the Rab and Vps33 module, but requires all six subunits for activity. At the center of HOPS and CORVET, the class C proteins Vps11 and Vps18 connect the two parts, and Vps11 binds both HOPS Vps39 and CORVET Vps3 via the same binding site. As HOPS Vps39 is also found at endosomes, our data thus suggest that these tethering complexes follow defined but distinct assembly pathways, and may undergo transition by simple subunit interchange.
    Keywords hops ; vacuoles
    Language English
    Dates of publication 2010-10
    Size p. 1334-1346.
    Publisher Blackwell Publishing Ltd
    Publishing place Oxford, UK
    Document type Article
    ZDB-ID 1483852-7
    ISSN 1600-0854 ; 1398-9219
    ISSN (online) 1600-0854
    ISSN 1398-9219
    DOI 10.1111/j.1600-0854.2010.01097.x
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Defined subunit arrangement and rab interactions are required for functionality of the HOPS tethering complex.

    Ostrowicz, Clemens W / Bröcker, Cornelia / Ahnert, Franziska / Nordmann, Mirjana / Lachmann, Jens / Peplowska, Karolina / Perz, Angela / Auffarth, Kathrin / Engelbrecht-Vandré, Siegfried / Ungermann, Christian

    Traffic (Copenhagen, Denmark)

    2010  Volume 11, Issue 10, Page(s) 1334–1346

    Abstract: Within the endomembrane system of eukaryotic cells, multisubunit tethering complexes together with their corresponding Rab-GTPases coordinate vesicle tethering and fusion. Here, we present evidence that two homologous hexameric tethering complexes, the ... ...

    Abstract Within the endomembrane system of eukaryotic cells, multisubunit tethering complexes together with their corresponding Rab-GTPases coordinate vesicle tethering and fusion. Here, we present evidence that two homologous hexameric tethering complexes, the endosomal CORVET (Class C core vacuole/endosome transport) and the vacuolar HOPS (homotypic vacuole fusion and protein sorting) complex, have similar subunit topologies. Both complexes contain two Rab-binding proteins at one end, and the Sec1/Munc18-like Vps33 at the opposite side, suggesting a model on membrane bridging via Rab-GTP and SNARE binding. In agreement, HOPS activity can be reconstituted using purified subcomplexes containing the Rab and Vps33 module, but requires all six subunits for activity. At the center of HOPS and CORVET, the class C proteins Vps11 and Vps18 connect the two parts, and Vps11 binds both HOPS Vps39 and CORVET Vps3 via the same binding site. As HOPS Vps39 is also found at endosomes, our data thus suggest that these tethering complexes follow defined but distinct assembly pathways, and may undergo transition by simple subunit interchange.
    MeSH term(s) Endosomes/metabolism ; GTP-Binding Protein alpha Subunits/chemistry ; GTP-Binding Protein alpha Subunits/metabolism ; Protein Interaction Domains and Motifs ; Saccharomyces cerevisiae/metabolism ; Saccharomyces cerevisiae Proteins/chemistry ; Saccharomyces cerevisiae Proteins/metabolism ; Vacuoles/metabolism ; Vesicular Transport Proteins/metabolism ; rab GTP-Binding Proteins/chemistry ; rab GTP-Binding Proteins/metabolism
    Chemical Substances GTP-Binding Protein alpha Subunits ; Saccharomyces cerevisiae Proteins ; Vesicular Transport Proteins ; rab GTP-Binding Proteins (EC 3.6.5.2)
    Language English
    Publishing date 2010-10
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1483852-7
    ISSN 1600-0854 ; 1398-9219
    ISSN (online) 1600-0854
    ISSN 1398-9219
    DOI 10.1111/j.1600-0854.2010.01097.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Factor H and atypical hemolytic uremic syndrome: mutations in the C-terminus cause structural changes and defective recognition functions.

    Józsi, Mihály / Heinen, Stefan / Hartmann, Andrea / Ostrowicz, Clemens W / Hälbich, Steffi / Richter, Heiko / Kunert, Anja / Licht, Christoph / Saunders, Rebecca E / Perkins, Stephen J / Zipfel, Peter F / Skerka, Christine

    Journal of the American Society of Nephrology : JASN

    2006  Volume 17, Issue 1, Page(s) 170–177

    Abstract: Atypical hemolytic uremic syndrome is a disease that is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Mutations in the complement regulator factor H are associated with the inherited form of the disease, ... ...

    Abstract Atypical hemolytic uremic syndrome is a disease that is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Mutations in the complement regulator factor H are associated with the inherited form of the disease, and >60% of the mutations are located within the C terminus of factor H. The C-terminus of factor H, represented by short consensus repeat 19 (SCR19) and SCR20, harbors multiple functions; consequently, this study aimed to examine the functional effects of clinically reported mutations in these SCR. Mutant factor H proteins (W1157R, W1183L, V1197A, R1210C, R1215G, and P1226S) were recombinantly expressed and functionally characterized. All six mutant proteins showed severely reduced heparin, C3b, C3d, and endothelial cell binding. By peptide spot analyses, four linear regions that are involved in heparin, C3b, and C3d binding were localized in SCR19 and SCR20. A three-dimensional homology model of the two domains suggests that these four regions form a common binding site across both domains. In addition, this structural model identifies two types of residues: Type A residues are positioned on the SCR surface and are represented by mutants W1157R, W1183L, R1210C, and R1215G; and type B residues are buried within the SCR structure and affect mutations V1197A and P1226S. Mutations of both types of residue result in the same functional defects, namely the reduced binding of factor H to surface-attached C3b molecules and reduced complement regulatory activity at the cell surfaces. The buried type B mutations seem to affect ligand interaction of factor H more severely than the surface-exposed mutations.
    MeSH term(s) Amino Acid Sequence ; Animals ; Cells, Cultured ; Complement C3b/metabolism ; Complement C3d/metabolism ; Complement Factor H/chemistry ; Complement Factor H/genetics ; Complement Factor H/physiology ; Endothelial Cells/metabolism ; Hemolytic-Uremic Syndrome/genetics ; Heparin/metabolism ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Spodoptera
    Chemical Substances Complement C3b (80295-43-8) ; Complement C3d (80295-45-0) ; Complement Factor H (80295-65-4) ; Heparin (9005-49-6)
    Language English
    Publishing date 2006-01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1085942-1
    ISSN 1533-3450 ; 1046-6673
    ISSN (online) 1533-3450
    ISSN 1046-6673
    DOI 10.1681/ASN.2005080868
    Database MEDical Literature Analysis and Retrieval System OnLINE

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