scholarly journals Vps501, a novel vacuolar SNX-BAR protein cooperates with the SEA complex to induce autophagy

2021 ◽  
Author(s):  
Shreya Goyal ◽  
Verónica A Segarra ◽  
Aaron M Stecher ◽  
Nitika ◽  
Andrew W Truman ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Phylogenetic Analyses ◽  
Vacuolar Membrane ◽  
Membrane Remodeling ◽  
Sorting Nexins ◽  
Autophagy Induction ◽  
Severe Deficiency ◽  
Organelle Motility ◽  
Phox Homology ◽  
Vacuolar Trafficking

The sorting nexins (SNX), constitute a diverse family of molecules that play varied roles in membrane trafficking, cell signaling, membrane remodeling, organelle motility and autophagy. In particular, the SNX-BAR proteins, a SNX subfamily characterized by a C-terminal dimeric Bin/Amphiphysin/Rvs (BAR) lipid curvature domain and a conserved Phox-homology domain, are of great interest. In budding yeast, many SNX-BARs proteins have well-characterized endo-vacuolar trafficking roles. Phylogenetic analyses allowed us to identify an additional SNX-BAR protein, Vps501, with a novel endo-vacuolar role. We report that Vps501 uniquely localizes to the vacuolar membrane and works with the SEA complex to regulate autophagy. Furthermore, we found cells displayed a severe deficiency in starvation-induced/nonselective autophagy only when SEA complex subunits are ablated in combination with Vps501, indicating a cooperative role with the SEA complex during autophagy. Additionally, we found the SEA complex becomes destabilized in vps501Δsea1Δ cells, which resulted in aberrant TORC1 hyperactivity and misregulation of autophagy induction.

Insights into the PX (phox-homology) domain and SNX (sorting nexin) protein families: structures, functions and roles in disease

2011 ◽  
Vol 441 (1) ◽  
pp. 39-59 ◽  
Author(s):  
Rohan D. Teasdale ◽  
Brett M. Collins
Keyword(s):  
Membrane Trafficking ◽  
Cell Signalling ◽  
Interaction Domain ◽  
Sorting Nexins ◽  
Pathogen Invasion ◽  
Px Domain ◽  
The Family ◽  
Endosomal Membranes ◽  
Almost All ◽  
Phox Homology

The mammalian genome encodes 49 proteins that possess a PX (phox-homology) domain, responsible for membrane attachment to organelles of the secretory and endocytic system via binding of phosphoinositide lipids. The PX domain proteins, most of which are classified as SNXs (sorting nexins), constitute an extremely diverse family of molecules that play varied roles in membrane trafficking, cell signalling, membrane remodelling and organelle motility. In the present review, we present an overview of the family, incorporating recent functional and structural insights, and propose an updated classification of the proteins into distinct subfamilies on the basis of these insights. Almost all PX domain proteins bind PtdIns3P and are recruited to early endosomal membranes. Although other specificities and localizations have been reported for a select few family members, the molecular basis for binding to other lipids is still not clear. The PX domain is also emerging as an important protein–protein interaction domain, binding endocytic and exocytic machinery, transmembrane proteins and many other molecules. A comprehensive survey of the molecular interactions governed by PX proteins highlights the functional diversity of the family as trafficking cargo adaptors and membrane-associated scaffolds regulating cell signalling. Finally, we examine the mounting evidence linking PX proteins to different disorders, in particular focusing on their emerging importance in both pathogen invasion and amyloid production in Alzheimer's disease.

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.

Organelle morphogenesis by active membrane remodeling

Soft Matter ◽  
2015 ◽  
Vol 11 (12) ◽  
pp. 2387-2393 ◽  
Author(s):  
N. Ramakrishnan ◽  
John H. Ipsen ◽  
Madan Rao ◽  
P. B. Sunil Kumar
Keyword(s):  
Membrane Trafficking ◽  
Eukaryotic Cells ◽  
Membrane Remodeling ◽  
Active Membrane ◽  
Internal Membrane ◽  
Membrane Bound ◽  
Morphological Identity ◽  
Non Equilibrium

Eukaryotic cells are characterized by having well defined internal membrane bound organelles with distinct morphological identity. We explore the issue of morphogenesis in the context of organelles subject to intense membrane trafficking and show that non-equilibrium driven processes are at the heart of organelle morphogenesis.

scholarly journals Requirement of the N-Terminal Extension for Vacuolar Trafficking and Transport Activity of Yeast Ycf1p, an ATP-binding Cassette Transporter

2002 ◽  
Vol 13 (12) ◽  
pp. 4443-4455 ◽  
Author(s):  
Deborah L. Mason ◽  
Susan Michaelis
Keyword(s):  
Abc Transporters ◽  
Membrane Trafficking ◽  
Critical Role ◽  
Vacuolar Membrane ◽  
Transport Processes ◽  
Proteolytic Processing ◽  
Atp Binding ◽  
Cadmium Resistance ◽  
Dependent Transport ◽  
Atp Binding Cassette

Ycf1p is the prototypical member of the yeast multidrug resistance-associated protein (MRP) subfamily of ATP-binding cassette (ABC) transporters. Ycf1p resides in the vacuolar membrane and mediates glutathione-dependent transport processes that result in resistance to cadmium and other xenobiotics. A feature common to many MRP proteins that distinguishes them from other ABC transporters is the presence of a hydrophobic N-terminal extension (NTE), whose function is not clearly established. The NTE contains a membrane spanning domain (MSD0) with five transmembrane spans and a cytosolic linker region (L0). The goal of this study was to determine the functional significance of the NTE of Ycf1p by examining the localization and functional properties of Ycf1p partial molecules, expressed either singly or together. We show that MSD0 plays a critical role in the vacuolar membrane trafficking of Ycf1p, whereas L0 is dispensable for localization. On the other hand, L0 is required for transport function, as determined by monitoring cadmium resistance. We also examine an unusual aspect of Ycf1p biology, namely, the posttranslational proteolytic processing that occurs within a lumenal loop of Ycf1p. Processing is shown to be Pep4p dependent and thus serves as a convenient marker for proper vacuolar localization. The processed fragments associate with each other, suggesting that these natural cleavage products contribute together to Ycf1p function.

scholarly journals The VINE complex is a VPS9–domain GEF–containing SNX–BAR coat involved in endosomal sorting

2021 ◽  
Author(s):  
Shawn P Shortill ◽  
Mia S Frier ◽  
Michael Davey ◽  
Elizabeth Conibear
Keyword(s):  
Coat Protein ◽  
Membrane Trafficking ◽  
Protein Sorting ◽  
Vacuolar Membrane ◽  
Membrane Recruitment ◽  
Endosomal Sorting ◽  
Endosomal Recycling ◽  
N Terminus ◽  
Recycling Pathway ◽  
Inactivating Mutation

Membrane trafficking pathways perform important roles in establishing and maintaining the endolysosomal network. Retrograde protein sorting from the endosome is promoted by conserved SNX–BAR–containing coat complexes including retromer which enrich cargo at tubular microdomains and generate transport carriers. In metazoans, retromer cooperates with VARP, a conserved VPS9–domain GEF, to direct an endosomal recycling pathway. The function of the yeast VARP homolog Vrl1 has been overlooked due an inactivating mutation in commonly studied strains. Here, we demonstrate that Vrl1 has features of a SNX–BAR coat protein and forms an obligate complex with Vin1, the paralog of the retromer SNX–BAR protein Vps5. Unique features in the Vin1 N–terminus allow Vrl1 to distinguish it from Vps5, thereby forming what we have named the VINE complex. VINE occupies endosomal tubules and promotes the delivery of a conserved mannose 6–phosphate receptor–like protein to the vacuolar membrane. In addition to sorting functions, membrane recruitment by Vin1 is essential for Vrl1 GEF activity, suggesting that VINE is a multifunctional coat complex that regulates trafficking and signaling events at the endosome.

scholarly journals Ancient complement and lineage-specific evolution of the Sec7 ARF GEF proteins in eukaryotes

2019 ◽  
Vol 30 (15) ◽  
pp. 1846-1863 ◽  
Author(s):  
Shweta V. Pipaliya ◽  
Alexander Schlacht ◽  
Christen M. Klinger ◽  
Richard A. Kahn ◽  
Joel Dacks
Keyword(s):  
Membrane Trafficking ◽  
Protein Function ◽  
Phylogenetic Analyses ◽  
Guanine Nucleotide Exchange Factors ◽  
Nucleotide Exchange ◽  
Cellular Processes ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Gtpase Activating Proteins ◽  
Functionally Diverse

Guanine nucleotide exchange factors (GEFs) are the initiators of signaling by every regulatory GTPase, which in turn act to regulate a wide array of essential cellular processes. To date, each family of GTPases is activated by distinct families of GEFs. Bidirectional membrane trafficking is regulated by ADP-ribosylation factor (ARF) GTPases and the development throughout eukaryotic evolution of increasingly complex systems of such traffic required the acquisition of a functionally diverse cohort of ARF GEFs to control it. We performed phylogenetic analyses of ARF GEFs in eukaryotes, defined by the presence of the Sec7 domain, and found three subfamilies (BIG, GBF1, and cytohesins) to have been present in the ancestor of all eukaryotes. The four other subfamilies (EFA6/PSD, IQSEC7/BRAG, FBX8, and TBS) are opisthokont, holozoan, metazoan, and alveolate/haptophyte specific, respectively, and each is derived from cytohesins. We also identified a cytohesin-derived subfamily, termed ankyrin repeat-containing cytohesin, that independently evolved in amoebozoans and members of the SAR and haptophyte clades. Building on evolutionary data for the ARF family GTPases and their GTPase-­activating proteins allowed the generation of hypotheses about ARF GEF protein function(s) as well as a better understanding of the origins and evolution of cellular complexity in eukaryotes.

Rice OsVAMP714, a membrane-trafficking protein localized to the chloroplast and vacuolar membrane, is involved in resistance to rice blast disease

2016 ◽  
Vol 91 (1-2) ◽  
pp. 81-95 ◽  
Author(s):  
Shoji Sugano ◽  
Nagao Hayashi ◽  
Yasushi Kawagoe ◽  
Susumu Mochizuki ◽  
Haruhiko Inoue ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Rice Blast ◽  
Vacuolar Membrane ◽  
Rice Blast Disease ◽  
Blast Disease

A Novel, Retromer-Independent Role for Sorting Nexins 1 and 2 in RhoG-Dependent Membrane Remodeling

Traffic ◽  
2010 ◽  
Vol 11 (10) ◽  
pp. 1347-1362 ◽  
Author(s):  
Derek C. Prosser ◽  
Duvinh Tran ◽  
Allana Schooley ◽  
Beverly Wendland ◽  
Johnny K. Ngsee
Keyword(s):  
Membrane Remodeling ◽  
Sorting Nexins

scholarly journals Saccharomyces cerevisiae Env7 Is a Novel Serine/Threonine Kinase 16-Related Protein Kinase and Negatively Regulates Organelle Fusion at the Lysosomal Vacuole

2012 ◽  
Vol 33 (3) ◽  
pp. 526-542 ◽  
Author(s):  
Surya P. Manandhar ◽  
Florante Ricarte ◽  
Stephanie M. Cocca ◽  
Editte Gharakhanian
Keyword(s):  
Protein Kinase ◽  
Membrane Fusion ◽  
Phylogenetic Analyses ◽  
Vacuolar Membrane ◽  
Site Directed Mutagenesis ◽  
Organelle Biogenesis ◽  
Gene Encoding ◽  
Dynamic Structures

ABSTRACTMembrane fusion depends on conserved components and is responsible for organelle biogenesis and vesicular trafficking. Yeast vacuoles are dynamic structures analogous to mammalian lysosomes. We report here that yeast Env7 is a novel palmitoylated protein kinase ortholog that negatively regulates vacuolar membrane fusion. Microscopic and biochemical studies confirmed the localization of tagged Env7 at the vacuolar membrane and implicated membrane association via the palmitoylation of its N-terminal Cys13 to -15.In vitrokinase assays established Env7 as a protein kinase. Site-directed mutagenesis of the Env7 alanine-proline-glutamic acid (APE) motif Glu269 to alanine results in an unstable kinase-dead allele that is stabilized and redistributed to the detergent-resistant fraction by interruption of the proteasome systemin vivo. Palmitoylation-deficient Env7C13-15S is also kinase dead and mislocalizes to the cytoplasm. Microscopy studies established thatenv7Δ is defective in maintaining fragmented vacuoles during hyperosmotic response and in buds.ENV7function is not redundant with a similar role of vacuolar membrane kinase Yck3, as the two do not share a substrate, andENV7is not a suppressor ofyck3Δ. Bayesian phylogenetic analyses strongly supportENV7as an ortholog of the gene encoding human STK16, a Golgi apparatus protein kinase with undefined function. We propose that Env7 function in fusion/fission dynamics may be conserved within the endomembrane system.

Sign in / Sign up

Export Citation Format

Share Document