Tvp38, Tvp23, Tvp18 and Tvp15: Novel membrane proteins in the Tlg2-containing Golgi/endosome compartments of Saccharomyces cerevisiae
Department of Biotechnology, University of Tokyo, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan.Experimental Cell Research (Impact Factor: 3.25). 03/2007; 313(4):688-97. DOI: 10.1016/j.yexcr.2006.11.008
Four previously uncharacterized proteins (Tvp38, Tvp23, Tvp18 and Tvp15) were found in Tlg2-containing membrane by proteomic analysis of immunoisolated Golgi subcompartments of Saccharomyces cerevisiae (Inadome et al., Mol. Cell. Biol., 25 (2005) 7696-7710). Immunofluorescence double staining of HA-tagged Tvp proteins and myc-tagged tSNAREs supported that these proteins mainly localize in the Tlg2-containing compartments. Conserved sequences of Tvp38, Tvp23 and Tvp18 are found in higher eukaryotes, but these homologues have not been characterized yet. All Tvp proteins were nonessential for growth under laboratory conditions. Immunoprecipitation of Tvp proteins indicated that Tvp23, Tvp18 and Tvp15 are in an interactive network with Yip1-family proteins, Yip4 and Yip5. They may collectively assist in the effective maintenance/function of the late Golgi/endosomal compartments. Disruptions of tvp15 and tvp23 showed synthetic aggravation with ypt6 or ric1 null mutation. Processing of carboxypeptidase Y and alkaline phosphatase in tvp disruptants occurred as in the wild type.
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- "No distinct function could be allocated to any DedA or Tvp38 homolog thus far. The eukaryotic member of this family, Tvp38, was initially found in close association with proteins involved in vesicle fusion at the late-Golgi compartment  , suggesting an involvement of Tvp38 in membrane transport processes. Moreover, DedA homologs are crucial for virulence of pathogenic species and thus represent interesting candidates for novel drug targets . "
ABSTRACT: Membrane proteins of the DedA/Tvp38 protein family are involved in membrane integrity and virulence of pathogenic organisms. However, the structure and exact function of any member of this large protein family are still unclear. In the present study we analyzed the functional and structural properties of a DedA homolog. Purified YqjA variants from Escherichia coli are detectable in different oligomeric states and specific homo-interaction of YqjA monomers in the membrane were confirmed by formation of a disulfide bond in the C-terminal transmembrane helix. Moreover, alanine scanning mutagenesis exhibited different interaction sites crucial for YqjA activity vs. dimer formation. Copyright © 2015. Published by Elsevier B.V.
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- "In the multi-sequence alignment, selected parts of the amino acid sequences of Slr0305, Slr0509, Slr0232 and the chloroplast SNARE-associated protein At1g22850 of Arabidopsis thaliana (Khan et al., 2013) are shown. Other amino acid sequences used in the alignment are the Tvp38-protein of Saccharomyces cerevisiae (S288c) (Inadome et al., 2007) and the best characterized prokaryotic DedA-homologs YghB, YqjA, YdjX and YdjZ of E. coli (Doerrler et al., 2013). The multi-sequence alignment was performed using CLUSTAL 2.1 (Larkin et al., 2007; Goujon et al., 2010). "
ABSTRACT: Vesicle transfer processes in eukaryotes depend on specific proteins, which mediate the selective packing of cargo molecules for subsequent release out of the cells after vesicle fusion to the plasma membrane. The protein Tvp38 is conserved in yeasts and higher eukaryotes and potentially involved in vesicle transfer processes at the Golgi membrane. Members of the so-called "SNARE-associated proteins of the Tvp38-family" have also been identified in prokaryotes and those belong to the DedA protein family. Tvp38/DedA proteins are also conserved in cyanobacteria and chloroplasts. While only a single member of this family appears to be present in chloroplasts, cyanobacterial genomes typically encode multiple homologous proteins. Mainly based on our understanding of the DedA-homologous proteins of Escherichia coli, it appears likely that the function of these proteins in chloroplast and cyanobacteria involves stabilizing and organizing the structure of internal membrane systems.
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- "ins , yeast YIP4p interacts with TVP23p , the yeast ortholog of ECH ( Gendre et al . , 2011 ) , as demonstrated by Y2H ( Uetz et al . , 2000 ; Ito et al . , 2001 ) and co - IP ( Inadome et al . , 2007 ) . Moreover , ECH and YIP4 localizations are also conserved across species , as both TVP23p and YIP4p localize to the late Golgi / early endosome ( Inadome et al . , 2007 ) , which corresponds to the plant TGN . Thus , ECH and YIP4a / b localizations and interaction have been conserved through evolution between the organisms as distant as yeast and plants , indicating their functional impor - tance for vesicle trafficking ."
ABSTRACT: The secretion of cell wall polysaccharides through the trans-Golgi network (TGN) is required for plant cell elongation. However, the components mediating the post-Golgi secretion of pectin and hemicellulose, the two major cell wall polysaccharides, are largely unknown. We identified evolutionarily conserved YPT/RAB GTPase Interacting Protein 4a (YIP4a) and YIP4b (formerly YIP2), which form a TGN-localized complex with ECHIDNA (ECH) in Arabidopsis thaliana. The localization of YIP4 and ECH proteins at the TGN is interdependent and influences the localization of VHA-a1 and SYP61, which are key components of the TGN. YIP4a and YIP4b act redundantly, and the yip4a yip4b double mutants have a cell elongation defect. Genetic, biochemical, and cell biological analyses demonstrate that the ECH/YIP4 complex plays a key role in TGN-mediated secretion of pectin and hemicellulose to the cell wall in dark-grown hypocotyls and in secretory cells of the seed coat. In keeping with these observations, Fourier transform infrared microspectroscopy analysis revealed that the ech and yip4a yip4b mutants exhibit changes in their cell wall composition. Overall, our results reveal a TGN subdomain defined by ECH/YIP4 that is required for the secretion of pectin and hemicellulose and distinguishes the role of the TGN in secretion from its roles in endocytic and vacuolar trafficking.
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