Tvp38, Tvp23, Tvp18 and Tvp15: novel membrane proteins in the Tlg2-containing Golgi/endosome compartments of Saccharomyces cerevisiae.
ABSTRACT 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.
- SourceAvailable from: Andreas Sjödin
[Show abstract] [Hide abstract]
- "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.The Plant Cell 07/2013; 25(7). DOI:10.1105/tpc.113.112482 · 9.58 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Ludox density gradients were used to enrich for Escherichia coli mutants with conditional growth defects and alterations in membrane composition. A temperature-sensitive mutant named Lud135 was isolated with mutations in two related, nonessential genes: yghB and yqjA. yghB harbors a single missense mutation (G203D) and yqjA contains a nonsense mutation (W92TGA) in Lud135. Both mutations are required for the temperature-sensitive phenotype: targeted deletion of both genes in a wild-type background results in a strain with a similar phenotype and expression of either gene from a plasmid restores growth at elevated temperatures. The mutant has altered membrane phospholipid levels, with elevated levels of acidic phospholipids, when grown under permissive conditions. Growth of Lud135 under nonpermissive conditions is restored by the presence of millimolar concentrations of divalent cations Ca(2+), Ba(2+), Sr(2+), or Mg(2+) or 300 to 500 mM NaCl but not 400 mM sucrose. Microscopic analysis of Lud135 demonstrates a dramatic defect at a late stage of cell division when cells are grown under permissive conditions. yghB and yqjA belong to the conserved and widely distributed dedA gene family, for which no function has been reported. The two open reading frames encode predicted polytopic inner membrane proteins with 61% amino acid identity. It is likely that YghB and YqjA play redundant but critical roles in membrane biology that are essential for completion of cell division in E. coli.Journal of bacteriology 08/2008; 190(13):4489-500. DOI:10.1128/JB.00414-08 · 2.69 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) proteins contribute to specific recognition between transport vesicles and target membranes and are required for fusion of membranes. The SNARE Vti1p is required for several transport steps between late Golgi, endosomes and the vacuole in the yeast Saccharomyces cerevisiae. Here, we identified the late Golgi membrane protein TVP23 as a multicopy suppressor of the growth defect in vti1-2 cells. By contrast, the growth defect in vti1-11 cells was not suppressed by TVP23 overexpression. Deletion of TVP23 aggravated the growth defect in vti1-2 cells. Genetic interactions between TVP23 and vti1-2 were not found in transport from the late Golgi via the late endosome to the vacuole or in transport from the Golgi directly to the vacuole. These results suggest that Tvp23p is not involved in forward transport from the late Golgi. Therefore retrograde traffic to the late Golgi was analysed. vti1-2 cells accumulated GFP (green fluorescent protein)-Snc1p within the cell, indicating that retrograde transport from the early endosome to the late Golgi was defective in these cells. Deletion of TVP23 in vti1-2 cells resulted in a synthetic defect in GFP-Snc1p recycling, whereas tvp23Delta cells had a slight defect. These results indicate that Tvp23p performs a partially redundant function in retrograde transport from the early endosome to the late Golgi. This transport step was unaffected in vti1-11 cells, providing an explanation for the allele-specific multicopy suppression by TVP23.Biochemical Journal 04/2009; 419(1):229-36. DOI:10.1042/BJ20081973 · 4.78 Impact Factor