scholarly journals Interactions between Syntaxins Identify at Least Five SNARE Complexes within the Golgi/Prevacuolar System of the Arabidopsis Cell

2001 ◽  
Vol 12 (12) ◽  
pp. 3733-3743 ◽  
Author(s):  
Anton A. Sanderfoot ◽  
Valya Kovaleva ◽  
Diane C. Bassham ◽  
Natasha V. Raikhel
Keyword(s):  
Single Gene ◽  
Adaptor Protein ◽  
Gene Families ◽  
Snare Complex ◽  
Transport Vesicles ◽  
Protein Receptors ◽  
Member Gene ◽  
Model Plant Arabidopsis Thaliana ◽  
Prevacuolar Compartment ◽  
Golgi Network

The syntaxin family of soluble N-ethyl maleimide sensitive factor adaptor protein receptors (SNAREs) is known to play an important role in the fusion of transport vesicles with specific organelles. Twenty-four syntaxins are encoded in the genome of the model plant Arabidopsis thaliana. These 24 genes are found in 10 gene families and have been reclassified as syntaxins of plants (SYPs). Some of these gene families have been previously characterized, with the SYP2-type syntaxins being found in the prevacuolar compartment (PVC) and the SYP4-type syntaxins on thetrans-Golgi network (TGN). Here we report on two previously uncharacterized syntaxin groups. The SYP5 group is encoded by a two-member gene family, whereas SYP61 is a single gene. Both types of syntaxins are localized to multiple compartments of the endomembrane system, including the TGN and the PVC. These two groups of syntaxins form SNARE complexes with each other, and with other Arabidopsis SNAREs. On the TGN, SYP61 forms complexes with the SNARE VTI12 and either SYP41 or SYP42. SYP51 and SYP61 interact with each other and with VTI12, most likely also on the TGN. On the PVC, a SYP5-type syntaxin interacts specifically with a SYP2-type syntaxin, as well as the SNARE VTI11, forming a SNARE complex likely involved in TGN-to-PVC trafficking.

scholarly journals Interaction of the conserved oligomeric Golgi complex with t-SNARE Syntaxin5a/Sed5 enhances intra-Golgi SNARE complex stability

2007 ◽  
Vol 179 (6) ◽  
pp. 1179-1192 ◽  
Author(s):  
Anna Shestakova ◽  
Elena Suvorova ◽  
Oleksandra Pavliv ◽  
Galimat Khaidakova ◽  
Vladimir Lupashin
Keyword(s):  
Mammalian Cells ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Snare Complex ◽  
Yeast Cells ◽  
Cog Complex ◽  
Transport Vesicles ◽  
Protein Receptors ◽  
Conserved Oligomeric Golgi

Tethering factors mediate initial interaction of transport vesicles with target membranes. Soluble N-ethylmaleimide–sensitive fusion protein attachment protein receptors (SNAREs) enable consequent docking and membrane fusion. We demonstrate that the vesicle tether conserved oligomeric Golgi (COG) complex colocalizes and coimmunoprecipitates with intra-Golgi SNARE molecules. In yeast cells, the COG complex preferentially interacts with the SNARE complexes containing yeast Golgi target (t)-SNARE Sed5p. In mammalian cells, hCog4p and hCog6p interact with Syntaxin5a, the mammalian homologue of Sed5p. Moreover, fluorescence resonance energy transfer reveals an in vivo interaction between Syntaxin5a and the COG complex. Knockdown of the mammalian COG complex decreases Golgi SNARE mobility, produces an accumulation of free Syntaxin5, and decreases the steady-state levels of the intra-Golgi SNARE complex. Finally, overexpression of the hCog4p N-terminal Syntaxin5a-binding domain destabilizes intra-Golgi SNARE complexes, disrupting the Golgi. These data suggest that the COG complex orchestrates vesicular trafficking similarly in yeast and mammalian cells by binding to the t-SNARE Syntaxin5a/Sed5p and enhancing the stability of intra-Golgi SNARE complexes.

scholarly journals Yeast Golgi-localized, γ-Ear–containing, ADP-Ribosylation Factor-binding Proteins Are but Adaptor Protein-1 Is Not Required for Cell-free Transport of Membrane Proteins from the Trans-Golgi Network to the Prevacuolar Compartment

2008 ◽  
Vol 19 (11) ◽  
pp. 4826-4836 ◽  
Author(s):  
Mohamed E. Abazeed ◽  
Robert S. Fuller
Keyword(s):  
Binding Proteins ◽  
Adaptor Protein ◽  
Early Endosome ◽  
Dominant Negative ◽  
Factor Binding ◽  
Trans Golgi Network ◽  
Direct Pathway ◽  
Prevacuolar Compartment ◽  
Golgi Network ◽  
Adp Ribosylation Factor

Golgi-localized, γ-Ear–containing, ADP-ribosylation factor-binding proteins (GGAs) and adaptor protein-1 (AP-1) mediate clathrin-dependent trafficking of transmembrane proteins between the trans-Golgi network (TGN) and endosomes. In yeast, the vacuolar sorting receptor Vps10p follows a direct pathway from the TGN to the late endosome/prevacuolar compartment (PVC), whereas, the processing protease Kex2p partitions between the direct pathway and an indirect pathway through the early endosome. To examine the roles of the Ggas and AP-1 in TGN–PVC transport, we used a cell-free assay that measures delivery to the PVC of either Kex2p or a chimeric protein (K-V), in which the Vps10p cytosolic tail replaces the Kex2p tail. Either antibody inhibition or dominant-negative Gga2p completely blocked K-V transport but only partially blocked Kex2p transport. Deletion of APL2, encoding the β subunit of AP-1, did not affect K-V transport but partially blocked Kex2p transport. Residual Kex2p transport seen with apl2Δ membranes was insensitive to dominant-negative Gga2p, suggesting that the apl2Δ mutation causes Kex2p to localize to a compartment that precludes Gga-dependent trafficking. These results suggest that yeast Ggas facilitate the specific and direct delivery of Vps10p and Kex2p from the TGN to the PVC and that AP-1 modulates Kex2p trafficking through a distinct pathway, presumably involving the early endosome.

scholarly journals Dual Roles of the Mammalian GARP Complex in Tethering and SNARE Complex Assembly at the trans-Golgi Network

2009 ◽  
Vol 29 (19) ◽  
pp. 5251-5263 ◽  
Author(s):  
F. Javier Pérez-Victoria ◽  
Juan S. Bonifacino
Keyword(s):  
Retrograde Transport ◽  
Terminal Region ◽  
Snare Complex ◽  
Dual Roles ◽  
Vesicle Tethering ◽  
Transport Vesicles ◽  
Initial Interaction ◽  
Golgi Network ◽  
Garp Complex

ABSTRACT Tethering factors and SNAREs control the last two steps of vesicular trafficking: the initial interaction and the fusion, respectively, of transport vesicles with target membranes. The Golgi-associated retrograde protein (GARP) complex regulates retrograde transport from endosomes to the trans-Golgi network (TGN). Although GARP has been proposed to function as a tethering factor at the TGN, direct evidence for such a role is still lacking. Herein we report novel and specific interactions of the mammalian GARP complex with SNAREs that participate in endosome-to-TGN transport, namely, syntaxin 6, syntaxin 16, and Vamp4. These interactions depend on the N-terminal regions of Vps53 and Vps54 and the SNARE motif of the SNAREs. We show that GARP functions upstream of the SNAREs, regulating their localization and assembly into SNARE complexes. However, interactions of GARP with SNAREs are insufficient to promote retrograde transport, because deletion of the C-terminal region of Vps53 precludes GARP function without affecting GARP-SNARE interactions. Finally, we present in vitro data consistent with a tethering role for GARP, which is disrupted by deletion of the Vps53 C-terminal region. These findings indicate that GARP orchestrates retrograde transport from endosomes to the TGN by promoting vesicle tethering and assembly of SNARE complexes in consecutive, independent steps.

scholarly journals AtVPS45 Complex Formation at thetrans-Golgi Network

2000 ◽  
Vol 11 (7) ◽  
pp. 2251-2265 ◽  
Author(s):  
Diane C. Bassham ◽  
Anton A. Sanderfoot ◽  
Valentina Kovaleva ◽  
Haiyan Zheng ◽  
Natasha V. Raikhel
Keyword(s):  
Secretory Pathway ◽  
Gene Families ◽  
Immunogold Electron Microscopy ◽  
Fusion Reactions ◽  
Attachment Protein ◽  
Sensitive Factor ◽  
Protein Receptors ◽  
Target Membrane ◽  
Functional Complexity ◽  
Golgi Network

The Sec1p family of proteins are thought to be involved in the regulation of vesicle fusion reactions through interaction with t-SNAREs (target soluble N-ethylmaleimide–sensitive factor attachment protein receptors) at the target membrane. AtVPS45 is a member of this family from Arabidopsis thaliana that we now demonstrate to be present on the trans-Golgi network (TGN), where it colocalizes with the vacuolar cargo receptor AtELP. Unlike yeast Vps45p, AtVPS45 does not interact with, or colocalize with, the prevacuolar t-SNARE AtPEP12. Instead, AtVPS45 interacts with two t-SNAREs, AtTLG2a and AtTLG2b, that show similarity to the yeast t-SNARE Tlg2p. AtTLG2a and -b each colocalize with AtVPS45 at the TGN; however, AtTLG2a is in a different region of the TGN than AtTLG2b by immunogold electron microscopy. Therefore, we propose that complexes containing AtVPS45 and either AtTLG2a or -b define functional subdomains of the TGN and may be required for different trafficking events. Among other Arabidopsis SNAREs, AtVPS45 antibodies preferentially coprecipitate AtVTI1b over the closely related isoform AtVTI1a, implying that AtVTI1a and AtVTI1b also have distinct functions within the cell. These data point to a functional complexity within the plant secretory pathway, where proteins encoded by gene families have specialized functions, rather than functional redundancy.

scholarly journals Participation of the Syntaxin 5/Ykt6/GS28/GS15 SNARE Complex in Transport from the Early/Recycling Endosome to the Trans-Golgi Network

2004 ◽  
Vol 15 (9) ◽  
pp. 4011-4022 ◽  
Author(s):  
Guihua Tai ◽  
Lei Lu ◽  
Tuan Lao Wang ◽  
Bor Luen Tang ◽  
Bruno Goud ◽  
...  
Keyword(s):  
Snare Complex ◽  
Recycling Endosome ◽  
Trans Golgi Network ◽  
B Subunit ◽  
Protein Receptors ◽  
Transport Assay ◽  
Golgi Network ◽  
Kinetics Of ◽  
Kinetics Of Inhibition

An in vitro transport assay, established with a modified Shiga toxin B subunit (STxB) as a marker, has proved to be useful for the study of transport from the early/recycling endosome (EE/RE) to the trans-Golgi network (TGN). Here, we modified this assay to test antibodies to all known soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) that have been shown to localize in the Golgi and found that syntaxin 5, GS28, Ykt6, and GS15 antibodies specifically inhibited STxB transport. Because syntaxin 5, GS28, Ykt6, and GS15 exist as a unique SNARE complex, our observation indicates that these four SNAREs function as a complex in EE/RE-TGN transport. The importance of GS15 in EE/RE-TGN transport was further demonstrated by a block in recombinant STxB transport in HeLa cells when GS15 expression was knocked down by its small interfering iRNA. Morphological analyses showed that some GS15 and Ykt6 were redistributed from the Golgi to the endosomes when the recycling endosome was perturbed by SNX3-overexpression, suggesting that GS15 and Ykt6 might cycle between the endosomes and the Golgi apparatus. Further studies indicated that syntaxin 5 and syntaxin 16 exerted their role in EE/RE-TGN transport in an additive manner. The kinetics of inhibition exhibited by syntaxin 16 and syntaxin 5 antibodies is similar.

scholarly journals TheSaccharomyces cerevisiaev-SNARE Vti1p Is Required for Multiple Membrane Transport Pathways to the Vacuole

1999 ◽  
Vol 10 (6) ◽  
pp. 1719-1732 ◽  
Author(s):  
Gabriele Fischer von Mollard ◽  
Tom H. Stevens
Keyword(s):  
Alkaline Phosphatase ◽  
Membrane Traffic ◽  
Snare Complex ◽  
Eukaryotic Cells ◽  
Biosynthetic Pathways ◽  
Snare Protein ◽  
Transport Pathways ◽  
Transport Vesicles ◽  
Prevacuolar Compartment ◽  
Retrograde Traffic

The interaction between v-SNAREs on transport vesicles and t-SNAREs on target membranes is required for membrane traffic in eukaryotic cells. Here we identify Vti1p as the first v-SNARE protein found to be required for biosynthetic traffic into the yeast vacuole, the equivalent of the mammalian lysosome. Certain vti1-tsyeast mutants are defective in alkaline phosphatase transport from the Golgi to the vacuole and in targeting of aminopeptidase I from the cytosol to the vacuole. VTI1 interacts genetically with the vacuolar t-SNARE VAM3, which is required for transport of both alkaline phosphatase and aminopeptidase I to the vacuole. The v-SNARE Nyv1p forms a SNARE complex with Vam3p in homotypic vacuolar fusion; however, we find that Nyv1p is not required for any of the three biosynthetic pathways to the vacuole. v-SNAREs were thought to ensure specificity in membrane traffic. However, Vti1p also functions in two additional membrane traffic pathways: Vti1p interacts with the t-SNAREs Pep12p in traffic from the TGN to the prevacuolar compartment and with Sed5p in retrograde traffic to the cis-Golgi. The ability of Vti1p to mediate multiple fusion steps requires additional proteins to ensure specificity in membrane traffic.

scholarly journals Binding of cargo sorting signals to AP-1 enhances its association with ADP ribosylation factor 1–GTP

2008 ◽  
Vol 180 (3) ◽  
pp. 467-472 ◽  
Author(s):  
Intaek Lee ◽  
Balraj Doray ◽  
Jennifer Govero ◽  
Stuart Kornfeld
Keyword(s):  
Adaptor Protein ◽  
Adenosine Diphosphate ◽  
Core Domain ◽  
Transport Vesicles ◽  
Sorting Signals ◽  
Stable Association ◽  
Golgi Network ◽  
Adp Ribosylation Factor ◽  
Prevailing View ◽  
Cargo Sorting

The adaptor protein AP-1 is the major coat protein involved in the formation of clathrin-coated vesicles at the trans-Golgi network. The prevailing view is that AP-1 recruitment involves coincident binding to multiple low-affinity sites comprising adenosine diphosphate ribosylation factor 1 (Arf-1)–guanosine triphosphate (GTP), cargo sorting signals, and phosphoinositides. We now show that binding of cargo signal peptides to AP-1 induces a conformational change in its core domain that greatly enhances its interaction with Arf-1–GTP. In addition, we provide evidence for cross talk between the dileucine and tyrosine binding sites within the AP-1 core domain such that binding of a cargo signal to one site facilitates binding to the other site. The stable association of AP-1 with Arf-1–GTP, which is induced by cargo signals, would serve to provide sufficient time for adaptor polymerization and clathrin recruitment while ensuring the packaging of cargo molecules into the forming transport vesicles.

scholarly journals Cargo Sorting at the trans-Golgi Network for Shunting into Specific Transport Routes: Role of Arf Small G Proteins and Adaptor Complexes

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 531 ◽  
Author(s):  
Jing Zhi Anson Tan ◽  
Paul Anthony Gleeson
Keyword(s):  
G Proteins ◽  
Adaptor Protein ◽  
Coat Proteins ◽  
Transport Pathway ◽  
Trans Golgi Network ◽  
Transport Vesicles ◽  
Different Populations ◽  
The Individual ◽  
Golgi Network ◽  
Small G Proteins

The trans-Golgi network (TGN) is responsible for selectively recruiting newly synthesized cargo into transport carriers for delivery to their appropriate destination. In addition, the TGN is responsible for receiving and recycling cargo from endosomes. The membrane organization of the TGN facilitates the sorting of cargoes into distinct populations of transport vesicles. There have been significant advances in defining the molecular mechanism involved in the recognition of membrane cargoes for recruitment into different populations of transport carriers. This machinery includes cargo adaptors of the adaptor protein (AP) complex family, and monomeric Golgi-localized γ ear-containing Arf-binding protein (GGA) family, small G proteins, coat proteins, as well as accessory factors to promote budding and fission of transport vesicles. Here, we review this literature with a particular focus on the transport pathway(s) mediated by the individual cargo adaptors and the cargo motifs recognized by these adaptors. Defects in these cargo adaptors lead to a wide variety of diseases.

scholarly journals The Plant Vesicle-associated SNARE AtVTI1a Likely Mediates Vesicle Transport from theTrans-Golgi Network to the Prevacuolar Compartment

1999 ◽  
Vol 10 (7) ◽  
pp. 2251-2264 ◽  
Author(s):  
Haiyan Zheng ◽  
Gabriele Fischer von Mollard ◽  
Valentina Kovaleva ◽  
Tom H. Stevens ◽  
Natasha V. Raikhel
Keyword(s):  
Transport Process ◽  
Subcellular Fractionation ◽  
Amino Acid Identity ◽  
Yeast Protein ◽  
Alternative Pathways ◽  
Trans Golgi Network ◽  
Cell Extracts ◽  
Transport Vesicles ◽  
Prevacuolar Compartment ◽  
Golgi Network

Membrane traffic in eukaryotic cells relies on recognition between v-SNAREs on transport vesicles and t-SNAREs on target membranes. Here we report the identification of AtVTI1a and AtVTI1b, twoArabidopsis homologues of the yeast v-SNARE Vti1p, which is required for multiple transport steps in yeast. AtVTI1a and AtVTI1b share 60% amino acid identity with one another and are 32 and 30% identical to the yeast protein, respectively. By suppressing defects found in specific strains of yeast vti1temperature-sensitive mutants, we show that AtVTI1a can substitute for Vti1p in Golgi-to-prevacuolar compartment (PVC) transport, whereas AtVTI1b substitutes in two alternative pathways: the vacuolar import of alkaline phosphatase and the so-called cytosol-to-vacuole pathway used by aminopeptidase I. Both AtVTI1a and AtVTI1b are expressed in all major organs of Arabidopsis. Using subcellular fractionation and immunoelectron microscopy, we show that AtVTI1a colocalizes with the putative vacuolar cargo receptor AtELP on the trans-Golgi network and the PVC. AtVTI1a also colocalizes with the t-SNARE AtPEP12p to the PVC. In addition, AtVTI1a and AtPEP12p can be coimmunoprecipitated from plant cell extracts. We propose that AtVTI1a functions as a v-SNARE responsible for targeting AtELP-containing vesicles from the trans-Golgi network to the PVC, and that AtVTI1b is involved in a different membrane transport process.

scholarly journals Cargo sorting zones in the trans-Golgi network visualized by super-resolution confocal live imaging microscopy in plants

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yutaro Shimizu ◽  
Junpei Takagi ◽  
Emi Ito ◽  
Yoko Ito ◽  
Kazuo Ebine ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
High Speed ◽  
Super Resolution ◽  
Adaptor Protein ◽  
Transport Proteins ◽  
3D Localization ◽  
Golgi Network ◽  
Distinct Distribution ◽  
Vacuolar Trafficking ◽  
Cargo Sorting

AbstractThe trans-Golgi network (TGN) has been known as a key platform to sort and transport proteins to their final destinations in post-Golgi membrane trafficking. However, how the TGN sorts proteins with different destinies still remains elusive. Here, we examined 3D localization and 4D dynamics of TGN-localized proteins of Arabidopsis thaliana that are involved in either secretory or vacuolar trafficking from the TGN, by a multicolor high-speed and high-resolution spinning-disk confocal microscopy approach that we developed. We demonstrate that TGN-localized proteins exhibit spatially and temporally distinct distribution. VAMP721 (R-SNARE), AP (adaptor protein complex)−1, and clathrin which are involved in secretory trafficking compose an exclusive subregion, whereas VAMP727 (R-SNARE) and AP-4 involved in vacuolar trafficking compose another subregion on the same TGN. Based on these findings, we propose that the single TGN has at least two subregions, or “zones”, responsible for distinct cargo sorting: the secretory-trafficking zone and the vacuolar-trafficking zone.

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