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Microbiology (Reading, England) Jan 2019Coxiella burnetii is an obligate intracellular pathogen that causes acute and chronic Q fever. C. burnetii grows within a eukaryotic host cell in a vacuole highly...
Coxiella burnetii is an obligate intracellular pathogen that causes acute and chronic Q fever. C. burnetii grows within a eukaryotic host cell in a vacuole highly similar to a phagolysosome. Found worldwide, this environmentally stable pathogen is maintained in nature via chronic infection of ruminants. Aerosol-mediated infection of humans results in infection and usurpation of alveolar macrophages through mechanisms using a bacterial Type 4B Secretion System and secreted effector proteins. Advances in axenic culture and genetic systems are changing our understanding of the pathogen's physiology and intimate molecular manipulations of host cells during infection.
Topics: Acids; Bacterial Proteins; Bacterial Secretion Systems; Coxiella burnetii; Genome, Bacterial; Humans; Hydrogen-Ion Concentration; Phylogeny; Q Fever; Vacuoles
PubMed: 30422108
DOI: 10.1099/mic.0.000707 -
Sheng Wu Gong Cheng Xue Bao = Chinese... Jun 2023As a generally-recognized-as-safe microorganism, is a widely studied chassis cell for the production of high-value or bulk chemicals in the field of synthetic biology.... (Review)
Review
As a generally-recognized-as-safe microorganism, is a widely studied chassis cell for the production of high-value or bulk chemicals in the field of synthetic biology. In recent years, a large number of synthesis pathways of chemicals have been established and optimized in . by various metabolic engineering strategies, and the production of some chemicals have shown the potential of commercialization. As a eukaryote, . has a complete inner membrane system and complex organelle compartments, and these compartments generally have higher concentrations of the precursor substrates (such as acetyl-CoA in mitochondria), or have sufficient enzymes, cofactors and energy which are required for the synthesis of some chemicals. These features may provide a more suitable physical and chemical environment for the biosynthesis of the targeted chemicals. However, the structural features of different organelles hinder the synthesis of specific chemicals. In order to ameliorate the efficiency of product biosynthesis, researchers have carried out a number of targeted modifications to the organelles grounded on an in-depth analysis of the characteristics of different organelles and the suitability of the production of target chemicals biosynthesis pathway to the organelles. In this review, the reconstruction and optimization of the biosynthesis pathways for production of chemicals by organelle mitochondria, peroxisome, golgi apparatus, endoplasmic reticulum, lipid droplets and vacuole compartmentalization in . are reviewed in-depth. Current difficulties, challenges and future perspectives are highlighted.
Topics: Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Golgi Apparatus; Metabolic Engineering; Vacuoles
PubMed: 37401597
DOI: 10.13345/j.cjb.221030 -
ACS Chemical Biology Jun 2022Lipid metabolism is spatiotemporally regulated within cells, yet intervention into lipid functions at subcellular resolution remains difficult. Here, we report a method...
Lipid metabolism is spatiotemporally regulated within cells, yet intervention into lipid functions at subcellular resolution remains difficult. Here, we report a method that enables site-specific release of sphingolipids and cholesterol inside the vacuole in . Using this approach, we monitored real-time sphingolipid metabolic flux out of the vacuole by mass spectrometry and found that the endoplasmic reticulum-vacuole-tethering protein Mdm1 facilitated the metabolism of sphingoid bases into ceramides. In addition, we showed that cholesterol, once delivered into yeast using our method, could restore cell proliferation induced by ergosterol deprivation, overcoming the previously described sterol-uptake barrier under aerobic conditions. Together, these data define a new way to study intracellular lipid metabolism and transport from the vacuole in yeast.
Topics: Cholesterol; Intermediate Filament Proteins; Lipid Metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Sphingolipids; Vacuoles
PubMed: 35667650
DOI: 10.1021/acschembio.2c00120 -
Autophagy 2015Macroautophagy (hereafter autophagy) is one of the major degradation systems in eukaryotic cells, and its dysfunction may result in diseases ranging from...
Macroautophagy (hereafter autophagy) is one of the major degradation systems in eukaryotic cells, and its dysfunction may result in diseases ranging from neurodegeneration to cancer. Although most of the autophagy-related (Atg) proteins that function in this pathway were first identified in yeast, many were subsequently shown to have homologs in higher eukaryotes including humans, and the overall mechanism of autophagy is highly conserved. The most prominent feature of autophagy is the formation of a double-membrane sequestering compartment, the phagophore; this transient organelle surrounds part of the cytoplasm and matures into an autophagosome, which subsequently fuses with the vacuole or lysosome to allow degradation of the cargo. Much attention has focused on the process involved in phagophore nucleation and expansion, but many questions remain. Here, we identified the yeast protein Icy2, which we now name Atg41, as playing a role in autophagosome formation. Atg41 interacts with the transmembrane protein Atg9, a key component involved in autophagosome biogenesis, and both proteins display a similar localization profile. Under autophagy-inducing conditions the expression level of Atg41 increases dramatically and is regulated by the transcription factor Gcn4. This work provides further insight into the mechanism of Atg9 function and the dynamics of sequestering membrane formation during autophagy.
Topics: Autophagy; Carrier Proteins; Lysosomes; Phagosomes; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Vacuoles
PubMed: 26565778
DOI: 10.1080/15548627.2015.1107692 -
Autophagy Sep 2023Macroautophagy/autophagy is a process through which the phagophores engulf non-essential or damaged cellular materials, forming double-membrane autophagosomes (APs) and...
Macroautophagy/autophagy is a process through which the phagophores engulf non-essential or damaged cellular materials, forming double-membrane autophagosomes (APs) and fusing with lysosomes/vacuoles, after which the materials are degraded for recycling purposes. Autophagy is associated with increased cell survival under different stress conditions. AP-lysosome/vacuole fusion is a critical step in autophagy. Some mutant cells can accumulate phagophores under autophagy-induction conditions. Autophagy is interrupted when accumulated phagophores cannot fuse with lysosomes/vacuoles, resulting in a significant decrease in cell survivability. However, phagophore-lysosome/vacuole fusion has been reported in related mammalian cells and yeast mutant cells. This observation indicates that it is possible to restore a partial autophagy process after interruption. Furthermore, these findings indicate that phagophore closure is not a prerequisite for its fusion with the lysosome/vacuole in the mutant cells. The phagophore-lysosome/vacuole fusion strategy can significantly rescue defective autophagy due to failed phagophore closure. This commentary discusses the fusion of phagophores and lysosomes/vacuoles and implications of such fusion events.: AB: autophagic body; AL: autolysosome; AP: autophagosome; ATG: autophagy related; EM: electron microscopy; ESCRT: endosomal sorting complex required for transport; ET: electron tomography; FIB: focus ion beam; IM: inner membrane; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; OM; outer membrane; STX17: syntaxin 17; TEM: transmission electron microscopy; TM: transmembrane domain; Vps: vacuolar protein sorting; WT: wild-type.
Topics: Animals; Autophagosomes; Vacuoles; Saccharomyces cerevisiae; Autophagy; Lysosomes; Membrane Fusion; Mammals
PubMed: 37083184
DOI: 10.1080/15548627.2023.2205272 -
Biomedicine & Pharmacotherapy =... Oct 2019According to its different occurrence mechanism, programmed cell death (PCD) is divided into apoptosis, autophagy, necrosis, paraptosis and so on. Paraptosis is... (Review)
Review
According to its different occurrence mechanism, programmed cell death (PCD) is divided into apoptosis, autophagy, necrosis, paraptosis and so on. Paraptosis is morphologically different from apoptosis and autophagy, which exhibit cytoplasmic vacuolation derived from the ER, independent of caspase, absence of apoptotic morphology. Recent researches have implied that a variety of small molecule compounds, such as celastrol, curcumin, can induce paraptosis-associated cell death as the reagent to enhance anti-cancer activity. A better understanding of paraptosis will lay the foundation to develop new therapeutic strategies to treat human cancers that make full use of small-molecule compounds.
Topics: Animals; Apoptosis; Autophagy; Biological Products; Cell Line, Tumor; Endoplasmic Reticulum; Humans; Neoplasms; Protein Biosynthesis; Regulated Cell Death; Small Molecule Libraries; Vacuoles
PubMed: 31306970
DOI: 10.1016/j.biopha.2019.109203 -
Current Biology : CB Aug 2023Controlling intracellular osmolarity is essential to all cellular life. Cells that live in hypo-osmotic environments, such as freshwater, must constantly battle water...
Controlling intracellular osmolarity is essential to all cellular life. Cells that live in hypo-osmotic environments, such as freshwater, must constantly battle water influx to avoid swelling until they burst. Many eukaryotic cells use contractile vacuoles to collect excess water from the cytosol and pump it out of the cell. Although contractile vacuoles are essential to many species, including important pathogens, the mechanisms that control their dynamics remain unclear. To identify the basic principles governing contractile vacuole function, we investigate here the molecular mechanisms of two species with distinct vacuolar morphologies from different eukaryotic lineages: the discoban Naegleria gruberi and the amoebozoan slime mold Dictyostelium discoideum. Using quantitative cell biology, we find that although these species respond differently to osmotic challenges, they both use vacuolar-type proton pumps for filling contractile vacuoles and actin for osmoregulation, but not to power water expulsion. We also use analytical modeling to show that cytoplasmic pressure is sufficient to drive water out of contractile vacuoles in these species, similar to findings from the alveolate Paramecium multimicronucleatum. These analyses show that cytoplasmic pressure is sufficient to drive contractile vacuole emptying for a wide range of cellular pressures and vacuolar geometries. Because vacuolar-type proton-pump-dependent contractile vacuole filling and pressure-dependent emptying have now been validated in three eukaryotic lineages that diverged well over a billion years ago, we propose that this represents an ancient eukaryotic mechanism of osmoregulation.
Topics: Cytosol; Dictyostelium; Osmolar Concentration; Water-Electrolyte Balance; Vacuoles; Eukaryota; Water
PubMed: 37478864
DOI: 10.1016/j.cub.2023.06.061 -
The Journal of Biological Chemistry Dec 2021Legionella pneumophila is a facultative intracellular pathogen that uses the Dot/Icm Type IV secretion system (T4SS) to translocate many effectors into its host and... (Review)
Review
Legionella pneumophila is a facultative intracellular pathogen that uses the Dot/Icm Type IV secretion system (T4SS) to translocate many effectors into its host and establish a safe, replicative lifestyle. The bacteria, once phagocytosed, reside in a vacuolar structure known as the Legionella-containing vacuole (LCV) within the host cells and rapidly subvert organelle trafficking events, block inflammatory responses, hijack the host ubiquitination system, and abolish apoptotic signaling. This arsenal of translocated effectors can manipulate the host factors in a multitude of different ways. These proteins also contribute to bacterial virulence by positively or negatively regulating the activity of one another. Such effector-effector interactions, direct and indirect, provide the delicate balance required to maintain cellular homeostasis while establishing itself within the host. This review summarizes the recent progress in our knowledge of the structure-function relationship and biochemical mechanisms of select effector pairs from Legionella that work in opposition to one another, while highlighting the diversity of biochemical means adopted by this intracellular pathogen to establish a replicative niche within host cells.
Topics: Animals; Bacterial Proteins; Homeostasis; Host-Pathogen Interactions; Humans; Inflammation; Legionella pneumophila; Legionnaires' Disease; Type IV Secretion Systems; Ubiquitination; Vacuoles
PubMed: 34695417
DOI: 10.1016/j.jbc.2021.101340 -
The Journal of Cell Biology Dec 2020The intricacy of nuclear pore complex (NPC) biogenesis imposes risks of failure that can cause defects in nuclear transport and nuclear envelope (NE) morphology;...
The intricacy of nuclear pore complex (NPC) biogenesis imposes risks of failure that can cause defects in nuclear transport and nuclear envelope (NE) morphology; however, cellular mechanisms used to alleviate NPC assembly stress are not well defined. In the budding yeast Saccharomyces cerevisiae, we demonstrate that NVJ1- and MDM1-enriched NE-vacuole contacts increase when NPC assembly is compromised in several nup mutants, including nup116ΔGLFG cells. These interorganelle nucleus-vacuole junctions (NVJs) cooperate with lipid droplets to maintain viability and enhance NPC formation in assembly mutants. Additionally, NVJs function with ATG1 to remodel the NE and promote vacuole-dependent degradation of specific nucleoporins in nup116ΔGLFG cells. Importantly, NVJs significantly improve the physiology of NPC assembly mutants, despite having only negligible effects when NPC biogenesis is unperturbed. These results therefore define how NE-vacuole interorganelle contacts coordinate responses to mitigate deleterious cellular effects caused by disrupted NPC assembly.
Topics: Gene Deletion; Intermediate Filament Proteins; Nuclear Pore; Nuclear Pore Complex Proteins; Receptors, Cytoplasmic and Nuclear; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Vacuoles
PubMed: 33053148
DOI: 10.1083/jcb.202001165 -
Current Genetics Apr 2018All eukaryotes require the transition metal, iron, a redox active element that is an essential cofactor in many metabolic pathways, as well as an oxygen carrier. Iron... (Review)
Review
All eukaryotes require the transition metal, iron, a redox active element that is an essential cofactor in many metabolic pathways, as well as an oxygen carrier. Iron can also react to generate oxygen radicals such as hydroxyl radicals and superoxide anions, which are highly toxic to cells. Therefore, organisms have developed intricate mechanisms to acquire iron as well as to protect themselves from the toxic effects of excess iron. In fungi and plants, iron is stored in the vacuole as a protective mechanism against iron toxicity. Iron storage in the vacuole is mediated predominantly by the vacuolar metal importer Ccc1 in yeast and the homologous transporter VIT1 in plants. Transcription of yeast CCC1 expression is tightly controlled primarily by the transcription factor Yap5, which sits on the CCC1 promoter and activates transcription through the binding of Fe-S clusters. A second mechanism that regulates CCC1 transcription is through the Snf1 signaling pathway involved in low-glucose sensing. Snf1 activates stress transcription factors Msn2 and Msn4 to mediate CCC1 transcription. Transcriptional regulation by Yap5 and Snf1 are completely independent and provide for a graded response in Ccc1 expression. The identification of multiple independent transcriptional pathways that regulate the levels of Ccc1 under high iron conditions accentuates the importance of protecting cells from the toxic effects of high iron.
Topics: Basic-Leucine Zipper Transcription Factors; Cation Transport Proteins; DNA-Binding Proteins; Gene Expression Regulation, Fungal; Iron; Protein Serine-Threonine Kinases; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Signal Transduction; Transcription Factors; Vacuoles
PubMed: 29043483
DOI: 10.1007/s00294-017-0767-7