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The FEBS Journal Feb 2013Plant vacuoles are unique, multifunctional organelles among eukaryotes. Considerable new insights in plant vacuolar protein sorting have been obtained recently. The... (Review)
Review
Plant vacuoles are unique, multifunctional organelles among eukaryotes. Considerable new insights in plant vacuolar protein sorting have been obtained recently. The basic machinery of protein export from the endoplasmic reticulum to the Golgi and the classical route to the lytic vacuole and the protein storage vacuole shows many similarities to vacuolar/lysosomal sorting in other eukaryotes. However, as a result of its unique functions in plant defence and as a storage compartment, some plant-specific entities and sorting determinants appear to exist. The alternative post-Golgi route, as found in animals and yeast, probably exists in plants as well. Likely, adaptor protein complex 3 fulfils a central role in this route. A Golgi-independent route involving plant-specific endoplasmic reticulum bodies appears to provide sedentary organisms such as plants with extra flexibility to cope with changing environmental conditions.
Topics: Animals; Endoplasmic Reticulum; Golgi Apparatus; Humans; Plant Cells; Plant Proteins; Protein Transport; Vacuoles
PubMed: 23241209
DOI: 10.1111/febs.12092 -
The New Phytologist Jan 2021The coordinated control of ion transport across the two major membranes of differentiated plant cells, the plasma and the vacuolar membranes, is fundamental in cell... (Review)
Review
The coordinated control of ion transport across the two major membranes of differentiated plant cells, the plasma and the vacuolar membranes, is fundamental in cell physiology. The stomata responses to the fluctuating environmental conditions are an illustrative example. Indeed, they rely on the coordination of ion fluxes between the different cell compartments. The cytosolic environment, which is an interface between intracellular compartments, and the activity of the ion transporters localised in the different membranes influence one each other. Here we analyse the molecular mechanisms connecting and modulating the transport processes at both the plasma and the vacuolar membranes of guard cells.
Topics: Arabidopsis; Biological Transport; Cell Membrane; Ion Transport; Vacuoles
PubMed: 33007120
DOI: 10.1111/nph.16983 -
Autophagy May 2016The macroautophagy (hereafter autophagy) process involves de novo formation of double-membrane autophagosomes; after sequestering cytoplasm these transient organelles... (Review)
Review
The macroautophagy (hereafter autophagy) process involves de novo formation of double-membrane autophagosomes; after sequestering cytoplasm these transient organelles fuse with the vacuole/lysosome. Genetic studies in yeasts have characterized more than 40 autophagy-related (Atg) proteins required for autophagy, and the majority of these proteins play roles in autophagosome formation. The fusion of autophagosomes with the vacuole is mediated by the Rab GTPase Ypt7, its guanine nucleotide exchange factor Mon1-Ccz1, and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. However, these factors are not autophagosome-vacuole fusion specific. We recently showed that 2 autophagy scaffold proteins, the Atg17-Atg31-Atg29 complex and Atg11, regulate autophagosome-vacuole fusion by recruiting the vacuolar SNARE Vam7 to the phagophore assembly site (PAS), where an autophagosome forms in yeast.
Topics: Animals; Autophagosomes; Autophagy; Autophagy-Related Proteins; Carrier Proteins; Humans; Phagosomes; Vacuoles
PubMed: 26986547
DOI: 10.1080/15548627.2016.1162364 -
Molecular Biology of the Cell Mar 2012Size and copy number of organelles are influenced by an equilibrium of membrane fusion and fission. We studied this equilibrium on vacuoles-the lysosomes of yeast....
Size and copy number of organelles are influenced by an equilibrium of membrane fusion and fission. We studied this equilibrium on vacuoles-the lysosomes of yeast. Vacuole fusion can readily be reconstituted and quantified in vitro, but it had not been possible to study fission of the organelle in a similar way. Here we present a cell-free system that reconstitutes fragmentation of purified yeast vacuoles (lysosomes) into smaller vesicles. Fragmentation in vitro reproduces physiological aspects. It requires the dynamin-like GTPase Vps1p, V-ATPase pump activity, cytosolic proteins, and ATP and GTP hydrolysis. We used the in vitro system to show that the vacuole-associated TOR complex 1 (TORC1) stimulates vacuole fragmentation but not the opposing reaction of vacuole fusion. Under nutrient restriction, TORC1 is inactivated, and the continuing fusion activity then dominates the fusion/fission equilibrium, decreasing the copy number and increasing the volume of the vacuolar compartment. This result can explain why nutrient restriction not only induces autophagy and a massive buildup of vacuolar/lysosomal hydrolases, but also leads to a concomitant increase in volume of the vacuolar compartment by coalescence of the organelles into a single large compartment.
Topics: Cell-Free System; GTP-Binding Proteins; Guanosine Triphosphate; Hydrolysis; Intracellular Membranes; Membrane Fusion; Protein Phosphatase 2; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Sirolimus; Transcription Factors; Vacuoles; Vesicular Transport Proteins
PubMed: 22238359
DOI: 10.1091/mbc.E11-08-0703 -
Microbiological Reviews Mar 1994The gas vesicle is a hollow structure made of protein. It usually has the form of a cylindrical tube closed by conical end caps. Gas vesicles occur in five phyla of the... (Review)
Review
The gas vesicle is a hollow structure made of protein. It usually has the form of a cylindrical tube closed by conical end caps. Gas vesicles occur in five phyla of the Bacteria and two groups of the Archaea, but they are mostly restricted to planktonic microorganisms, in which they provide buoyancy. By regulating their relative gas vesicle content aquatic microbes are able to perform vertical migrations. In slowly growing organisms such movements are made more efficiently than by swimming with flagella. The gas vesicle is impermeable to liquid water, but it is highly permeable to gases and is normally filled with air. It is a rigid structure of low compressibility, but it collapses flat under a certain critical pressure and buoyancy is then lost. Gas vesicles in different organisms vary in width, from 45 to > 200 nm; in accordance with engineering principles the narrower ones are stronger (have higher critical pressures) than wide ones, but they contain less gas space per wall volume and are therefore less efficient at providing buoyancy. A survey of gas-vacuolate cyanobacteria reveals that there has been natural selection for gas vesicles of the maximum width permitted by the pressure encountered in the natural environment, which is mainly determined by cell turgor pressure and water depth. Gas vesicle width is genetically determined, perhaps through the amino acid sequence of one of the constituent proteins. Up to 14 genes have been implicated in gas vesicle production, but so far the products of only two have been shown to be present in the gas vesicle: GvpA makes the ribs that form the structure, and GvpC binds to the outside of the ribs and stiffens the structure against collapse. The evolution of the gas vesicle is discussed in relation to the homologies of these proteins.
Topics: Amino Acid Sequence; Bacteria; Bacterial Physiological Phenomena; Bacterial Proteins; Cyanobacteria; Gases; Genes, Bacterial; Halobacterium; Models, Biological; Molecular Sequence Data; Vacuoles
PubMed: 8177173
DOI: 10.1128/mr.58.1.94-144.1994 -
Oncotarget Aug 2016Cytoplasmic vacuolization (also called cytoplasmic vacuolation) is a well-known morphological phenomenon observed in mammalian cells after exposure to bacterial or viral... (Review)
Review
Cytoplasmic vacuolization (also called cytoplasmic vacuolation) is a well-known morphological phenomenon observed in mammalian cells after exposure to bacterial or viral pathogens as well as to various natural and artificial low-molecular-weight compounds. Vacuolization often accompanies cell death; however, its role in cell death processes remains unclear. This can be attributed to studying vacuolization at the level of morphology for many years. At the same time, new data on the molecular mechanisms of the vacuole formation and structure have become available. In addition, numerous examples of the association between vacuolization and previously unknown cell death types have been reported. Here, we review these data to make a deeper insight into the role of cytoplasmic vacuolization in cell death and survival.
Topics: Animals; Bacterial Infections; Bacterial Proteins; Cell Death; Cell Survival; Cytoplasm; Endoplasmic Reticulum; Endoplasmic Reticulum-Associated Degradation; Humans; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; Necrosis; Vacuoles; Virus Diseases
PubMed: 27331412
DOI: 10.18632/oncotarget.10150 -
Biochimica Et Biophysica Acta Apr 2009Fungal vacuoles are acidic organelles with degradative and storage capabilities that have many similarities to mammalian lysosomes and plant vacuoles. In the past... (Review)
Review
Fungal vacuoles are acidic organelles with degradative and storage capabilities that have many similarities to mammalian lysosomes and plant vacuoles. In the past several years, well-developed genetic, genomic, biochemical and cell biological tools in S. cerevisiae have provided fresh insights into vacuolar protein sorting, organelle acidification, ion homeostasis, autophagy, and stress-related functions of the vacuole, and these insights have often found parallels in mammalian lysosomes. This review provides a broad overview of the defining features and functions of S. cerevisiae vacuoles and compares these features to mammalian lysosomes. Recent research challenges the traditional view of vacuoles and lysosomes as simply the terminal compartment of biosynthetic and endocytic pathways (i.e. the "garbage dump" of the cell), and suggests instead that these compartments are unexpectedly dynamic and highly regulated.
Topics: Acids; Lysosomes; Protein Transport; Saccharomyces cerevisiae; Stress, Physiological; Vacuoles
PubMed: 18786576
DOI: 10.1016/j.bbamcr.2008.08.003 -
Biochimica Et Biophysica Acta.... May 2019Cellular ageing results in accumulating damage to various macromolecules and the progressive decline of organelle function. Yeast vacuoles as well as their counterpart... (Review)
Review
Cellular ageing results in accumulating damage to various macromolecules and the progressive decline of organelle function. Yeast vacuoles as well as their counterpart in higher eukaryotes, the lysosomes, emerge as central organelles in lifespan determination. These acidic organelles integrate enzymatic breakdown and recycling of cellular waste with nutrient sensing, storage, signalling and mobilization. Establishing physical contact with virtually all other organelles, vacuoles serve as hubs of cellular homeostasis. Studies in Saccharomyces cerevisiae contributed substantially to our understanding of the ageing process per se and the multifaceted roles of vacuoles/lysosomes in the maintenance of cellular fitness with progressing age. Here, we discuss the multiple roles of the vacuole during ageing, ranging from vacuolar dynamics and acidification as determinants of lifespan to the function of this organelle as waste bin, recycling facility, nutrient reservoir and integrator of nutrient signalling.
Topics: Lysosomes; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Time Factors; Vacuoles
PubMed: 30796938
DOI: 10.1016/j.bbamcr.2019.02.011 -
Cellular Microbiology Jul 2015Bacteria of the genus Brucella are intracellular vacuolar pathogens of mammals that cause the worldwide zoonosis brucellosis, and reside within phagocytes of infected... (Review)
Review
Bacteria of the genus Brucella are intracellular vacuolar pathogens of mammals that cause the worldwide zoonosis brucellosis, and reside within phagocytes of infected hosts to promote their survival, persistence and proliferation. These traits are essential to the bacterium's ability to cause disease and have been the subject of much investigation to gain an understanding of Brucella pathogenic mechanisms. Although the endoplasmic reticulum-derived nature of the Brucella replicative niche has been long known, major strides have recently been made in deciphering the molecular mechanisms of its biogenesis, including the identification of bacterial determinants and host cellular pathways involved in this process. Here I will review and discuss the most recent advances in our knowledge of Brucella intracellular pathogenesis, with an emphasis on bacterial exploitation of the host endoplasmic reticulum-associated functions, and how autophagy-related processes contribute to the bacterium's intracellular cycle.
Topics: Animals; Brucella; Host-Pathogen Interactions; Humans; Mammals; Models, Biological; Phagocytes; Vacuoles; Virulence Factors
PubMed: 25916795
DOI: 10.1111/cmi.12452 -
Cells Jun 2022Cells rely on autophagy to degrade cytosolic material and maintain homeostasis. During autophagy, content to be degraded is encapsulated in double membrane vesicles,... (Review)
Review
Cells rely on autophagy to degrade cytosolic material and maintain homeostasis. During autophagy, content to be degraded is encapsulated in double membrane vesicles, termed autophagosomes, which fuse with the yeast vacuole for degradation. This conserved cellular process requires the dynamic rearrangement of membranes. As such, the process of autophagy requires many soluble proteins that bind to membranes to restructure, tether, or facilitate lipid transfer between membranes. Here, we review the methods that have been used to investigate membrane binding by the core autophagy machinery and additional accessory proteins involved in autophagy in yeast. We also review the key experiments demonstrating how each autophagy protein was shown to interact with membranes.
Topics: Autophagosomes; Autophagy; Proteins; Saccharomyces cerevisiae; Vacuoles
PubMed: 35741004
DOI: 10.3390/cells11121876