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Pathogens and Disease Aug 2019Chlamydia trachomatis is a significant pathogen with global and economic impact. As an obligate intracellular pathogen, C. trachomatis resides inside the inclusion, a...
Chlamydia trachomatis is a significant pathogen with global and economic impact. As an obligate intracellular pathogen, C. trachomatis resides inside the inclusion, a parasitophorous vacuole, and depends on the host cell for survival and transition through a biphasic development cycle. During infection, C. trachomatis is known to manipulate multiple signaling pathways and recruit an assortment of host proteins to the inclusion membrane, including host kinases. Here, we show recruitment of multiple isoforms of protein kinase C (PKC) including active phosphorylated PKC isoforms to the chlamydial inclusion colocalizing with active Src family kinases. Pharmacological inhibition of PKC led to a modest reduction of infectious progeny production. PKC phosphorylated substrates were seen recruited to the entire periphery of the inclusion membrane. Infected whole cell lysates showed altered PKC phosphorylation of substrates during the course of infection. Assessment of different chlamydial species showed recruitment of PKC and PKC phosphorylated substrates were limited to C. trachomatis. Taken together, PKC and PKC substrate recruitment may provide significant insights into how C. trachomatis manipulates multiple host signaling cascades during infection.
Topics: Chlamydia Infections; Chlamydia trachomatis; Epithelial Cells; HeLa Cells; Host-Pathogen Interactions; Humans; Phosphorylation; Protein Kinase C; Protein Processing, Post-Translational; Signal Transduction; Vacuoles
PubMed: 31647538
DOI: 10.1093/femspd/ftz061 -
Traffic (Copenhagen, Denmark) Feb 2008The human malaria parasite Plasmodium falciparum resides and multiplies within a membrane-bound vacuole in the cytosol of its host cell, the mature human erythrocyte. To... (Review)
Review
The human malaria parasite Plasmodium falciparum resides and multiplies within a membrane-bound vacuole in the cytosol of its host cell, the mature human erythrocyte. To enable the parasite to complete its intraerythrocytic life cycle, a large number of parasite proteins are synthesized and transported from the parasite to the infected cell. To gain access to the erythrocyte, parasite proteins must first cross the membrane of the parasitophorous vacuole (PVM), a process that is not well understood at the mechanistic level. Here, we review past and current literature on this topic, and make tentative predictions about the nature of the transport machinery required for transport of proteins across the PVM, and the molecular factors involved.
Topics: Animals; Erythrocytes; Humans; Membrane Transport Proteins; Models, Biological; Plasmodium falciparum; Protein Sorting Signals; Protein Transport; Vacuoles
PubMed: 17944805
DOI: 10.1111/j.1600-0854.2007.00648.x -
Plant Signaling & Behavior Jun 2016AtNHX5 and AtNHX6, endosomal Na(+),K(+)/H(+) antiporters in Arabidopsis, are localized in the Golgi, trans-Golgi network, and prevacuolear compartment. It becomes...
AtNHX5 and AtNHX6, endosomal Na(+),K(+)/H(+) antiporters in Arabidopsis, are localized in the Golgi, trans-Golgi network, and prevacuolear compartment. It becomes evident that AtNHX5 and AtNHX6 play an important role in protein transport toward the vacuole. Studies have shown that AtNHX5 and AtNHX6 regulate the transport of seed storage proteins as well as the biogenesis of the protein storage vacuoles. Three distinct mechanisms have been revealed for the roles of AtNHX5 and AtNHX6 in protein transport. AtNHX5 and AtNHX6 control: (i) the binding of VSR to its cargoes; (ii) the recycling of VSRs; and (iii) subcellular localization of the SNARE complex. Moreover, it has been found that the endosomal pH homeostasis maintained by AtNHX5 and AtNHX6 is critical for the transport of seed storage proteins. Taken together, AtNHX5 and AtNHX6 regulate the trafficking of seed storage proteins into the vacuole; the H(+) leak pathway conducted by AtNHX5 and AtNHX6 is critical for protein transport.
Topics: Arabidopsis; Arabidopsis Proteins; Models, Biological; Protein Transport; Protons; Vacuoles
PubMed: 27175802
DOI: 10.1080/15592324.2016.1184810 -
MBio Dec 2018is the causative agent of a pneumonia termed Legionnaires' disease. The facultative intracellular bacterium employs the Icm/Dot type IV secretion system (T4SS) and a...
is the causative agent of a pneumonia termed Legionnaires' disease. The facultative intracellular bacterium employs the Icm/Dot type IV secretion system (T4SS) and a plethora of translocated "effector" proteins to interfere with host vesicle trafficking pathways and establish a replicative niche, the -containing vacuole (LCV). Internalization of the pathogen and the events immediately ensuing are accompanied by host cell-mediated phosphoinositide (PI) lipid changes and the Icm/Dot-controlled conversion of the LCV from a PtdIns(3)-positive vacuole into a PtdIns(4)-positive replication-permissive compartment, which tightly associates with the endoplasmic reticulum. The source and formation of PtdIns(4) are ill-defined. Using dually labeled amoebae and real-time high-resolution confocal laser scanning microscopy (CLSM), we show here that nascent LCVs continuously capture and accumulate PtdIns(4)-positive vesicles from the host cell. Trafficking of these PtdIns(4)-positive vesicles to LCVs occurs independently of the Icm/Dot system, but their sustained association requires a functional T4SS. During the infection, PtdIns(3)-positive membranes become compacted and segregated from the LCV, and PtdIns(3)-positive vesicles traffic to the LCV but do not fuse. Moreover, using eukaryotic and prokaryotic PtdIns(4) probes (2×PH-green fluorescent protein [2×PH-GFP] and P4C-GFP, respectively) along with Arf1-GFP, we show that PtdIns(4)-rich membranes of the -Golgi network associate with the LCV. Intriguingly, the interaction dynamics of 2×PH-GFP and P4C-GFP are spatially separable and reveal the specific PtdIns(4) pool from which the LCV PI originates. These findings provide high-resolution real-time insights into how exploits the cellular dynamics of membrane-bound PtdIns(4) for LCV formation. The environmental bacterium causes a life-threatening pneumonia termed Legionnaires' disease. The bacteria grow intracellularly in free-living amoebae as well as in respiratory tract macrophages. To this end, forms a distinct membrane-bound compartment called the -containing vacuole (LCV). Phosphoinositide (PI) lipids are crucial regulators of the identity and dynamics of host cell organelles. The PI lipid PtdIns(4) is a hallmark of the host cell secretory pathway, and decoration of LCVs with this PI is required for pathogen vacuole maturation. The source, dynamics, and mode of accumulation of PtdIns(4) on LCVs are largely unknown. Using amoebae producing different fluorescent probes as host cells, we show here that LCVs rapidly acquire PtdIns(4) through the continuous interaction with PtdIns(4)-positive host vesicles derived from the Golgi apparatus. Thus, the PI lipid pattern of the secretory pathway contributes to the formation of the replication-permissive pathogen compartment.
Topics: Cytoplasmic Vesicles; Dictyostelium; Golgi Apparatus; Legionella pneumophila; Microscopy, Confocal; Phosphatidylinositol Phosphates; Type IV Secretion Systems; Vacuoles
PubMed: 30538188
DOI: 10.1128/mBio.02420-18 -
Journal of Microbiology and... Dec 2020Ergosterol, an essential constituent of membrane lipids of yeast, is distributed in both the cell membrane and intracellular endomembrane components such as vacuoles....
Ergosterol, an essential constituent of membrane lipids of yeast, is distributed in both the cell membrane and intracellular endomembrane components such as vacuoles. Honokiol, a major polyphenol isolated from , has been shown to inhibit the growth of . Here, we assessed the effect of honokiol on ergosterol biosynthesis and vacuole function in . Honokiol could decrease the ergosterol content and upregulate the expression of genes related with the ergosterol biosynthesis pathway. The exogenous supply of ergosterol attenuated the toxicity of honokiol against . Honokiol treatment could induce cytosolic acidification by blocking the activity of the plasma membrane Pma1p H-ATPase. Furthermore, honokiol caused abnormalities in vacuole morphology and function. Concomitant ergosterol feeding to some extent restored the vacuolar morphology and the function of acidification in cells treated by honokiol. Honokiol also disrupted the intracellular calcium homeostasis. Amiodarone attenuated the antifungal effects of honokiol against , probably due to the activation of the calcineurin signaling pathway which is involved in honokiol tolerance. In conclusion, this study demonstrated that honokiol could inhibit ergosterol biosynthesis and decrease Pma 1p H-ATPase activity, which resulted in the abnormal pH in vacuole and cytosol.
Topics: Antifungal Agents; Biphenyl Compounds; Calcineurin; Candida albicans; Drug Resistance, Fungal; Ergosterol; Lignans; Magnolia; Microbial Sensitivity Tests; Plant Extracts; Vacuoles
PubMed: 33263334
DOI: 10.4014/jmb.2008.08019 -
The Plant Cell May 2012Delivery of proteins to the lytic vacuole in plants is a complex cascade of selective interactions that specifically excludes residents of the endoplasmic reticulum and... (Review)
Review
Delivery of proteins to the lytic vacuole in plants is a complex cascade of selective interactions that specifically excludes residents of the endoplasmic reticulum and secreted proteins. Vacuolar transport must be highly efficient to avoid mistargeting of hydrolytic enzymes to locations where they could be harmful. While plant vacuolar sorting signals have been well described for two decades, it is only during the last 5 years that a critical mass of data was gathered that begins to reveal how vacuolar sorting receptors (VSRs) may complete a full transport cycle. Yet, the field is far from reaching a consensus regarding the organelles that could be involved in vacuolar sorting, their potential biogenesis, and the ultimate recycling of membranes and protein machinery that maintain this pathway. This review will highlight the important landmarks in our understanding of VSR function and compare recent transport models that have been proposed so that an emerging picture of plant vacuolar sorting mechanisms can be drawn.
Topics: Plant Proteins; Protein Transport; Vacuoles
PubMed: 22570446
DOI: 10.1105/tpc.112.095679 -
Annals of Botany Nov 2013Global annual losses in agricultural production from salt-affected land are in excess of US$12 billion and rising. At the same time, a significant amount of arable land... (Review)
Review
BACKGROUND
Global annual losses in agricultural production from salt-affected land are in excess of US$12 billion and rising. At the same time, a significant amount of arable land is becoming lost to urban sprawl, forcing agricultural production into marginal areas. Consequently, there is a need for a major breakthrough in crop breeding for salinity tolerance. Given the limited range of genetic diversity in this trait within traditional crops, stress tolerance genes and mechanisms must be identified in extremophiles and then introduced into traditional crops.
SCOPE AND CONCLUSIONS
This review argues that learning from halophytes may be a promising way of achieving this goal. The paper is focused around two central questions: what are the key physiological mechanisms conferring salinity tolerance in halophytes that can be introduced into non-halophyte crop species to improve their performance under saline conditions and what specific genes need to be targeted to achieve this goal? The specific traits that are discussed and advocated include: manipulation of trichome shape, size and density to enable their use for external Na(+) sequestration; increasing the efficiency of internal Na(+) sequestration in vacuoles by the orchestrated regulation of tonoplast NHX exchangers and slow and fast vacuolar channels, combined with greater cytosolic K(+) retention; controlling stomata aperture and optimizing water use efficiency by reducing stomatal density; and efficient control of xylem ion loading, enabling rapid shoot osmotic adjustment while preventing prolonged Na(+) transport to the shoot.
Topics: Adaptation, Physiological; Plant Stomata; Salt-Tolerant Plants; Sodium Chloride; Stress, Physiological; Vacuoles
PubMed: 24085482
DOI: 10.1093/aob/mct205 -
Malaria Journal Jun 2010The Plasmodium falciparum PfA-M1 aminopeptidase, encoded by a single copy gene, displays a neutral optimal activity at pH 7.4. It is thought to be involved in...
BACKGROUND
The Plasmodium falciparum PfA-M1 aminopeptidase, encoded by a single copy gene, displays a neutral optimal activity at pH 7.4. It is thought to be involved in haemoglobin degradation and/or invasion of the host cells. Although a series of inhibitors developed against PfA-M1 suggest that this enzyme is a promising target for therapeutic intervention, the biological function(s) of the three different forms of the enzyme (p120, p96 and p68) are not fully understood. Two recent studies using PfA-M1 transfections have also provided conflicting results on PfA-M1 localization within or outside the food vacuole. Alternative destinations, such as the nucleus, have also been proposed.
METHODS
By using a combination of techniques, such as cellular and biochemical fractionations, biochemical analysis, mass-spectrometry, immunofluorescence assays and live imaging of GFP fusions to various PfA-M1 domains, evidence is provided for differential localization and behaviour of the three different forms of PfA-M1 in the infected red blood cell which had not been established before.
RESULTS
The high molecular weight p120 form of PfA-M1, the only version of the protein with a hydrophobic transmembrane domain, is detected both inside the parasite and in the parasitophorous vacuole while the processed p68 form is strictly soluble and localized within the parasite. The transient intermediate and soluble p96 form is localized at the border of parasitophorous vacuole and within the parasite in a compartment sensitive to high concentrations of saponin. Upon treatment with brefeldin A, the PfA-M1 maturation is blocked and the enzyme remains in a compartment close to the nucleus.
CONCLUSIONS
The PfA-M1 trafficking/maturation scenario that emerges from this data indicates that PfA-M1, synthesized as the precursor p120 form, is targeted to the parasitophorous vacuole via the parasite endoplasmic reticulum/Golgi, where it is converted into the transient p96 form. This p96 form is eventually redirected into the parasite to be converted into the processed p68 form that is only marginally delivered to the parasite food vacuole. These results provide insights on PfA-M1 topology regarding key compartments of the infected red blood cells that have important implications for the development of inhibitors targeting this plasmodial enzyme.
Topics: Amino Acid Sequence; Aminopeptidases; Animals; Blotting, Western; Electrophoresis, Gel, Two-Dimensional; Erythrocytes; Fluorescent Antibody Technique; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Molecular Sequence Data; Plasmodium falciparum; Transfection; Vacuoles; Zinc
PubMed: 20591164
DOI: 10.1186/1475-2875-9-189 -
Acquisition of nutrients by Chlamydiae: unique challenges of living in an intracellular compartment.Current Opinion in Microbiology Feb 2010The Chlamydiae are obligate intracellular pathogens that replicate within a membrane-bound vacuole, termed the 'inclusion'. From this compartment, bacteria acquire... (Review)
Review
The Chlamydiae are obligate intracellular pathogens that replicate within a membrane-bound vacuole, termed the 'inclusion'. From this compartment, bacteria acquire essential nutrients by selectively redirecting transport vesicles and hijacking intracellular organelles. Rerouting is achieved by several mechanisms including proteolysis-mediated fragmentation of the Golgi apparatus, recruitment of Rab GTPases and SNAREs, and translocation of cytoplasmic organelles into the inclusion lumen. Given Chlamydiae's extended coevolution with eukaryotic cells, it is likely that co-option of multiple cellular pathways is a strategy to provide redundancy in the acquisition of essential nutrients from the host and has contributed to the success of these highly adapted pathogens.
Topics: Chlamydia; Chlamydia Infections; Eukaryotic Cells; Humans; Vacuoles
PubMed: 20006538
DOI: 10.1016/j.mib.2009.11.002 -
The EMBO Journal Mar 2002Selective membrane fusion underlies subcellular compartmentation, cell growth, neurotransmission and hormone secretion. Its fundamental mechanisms are conserved among... (Review)
Review
Selective membrane fusion underlies subcellular compartmentation, cell growth, neurotransmission and hormone secretion. Its fundamental mechanisms are conserved among organelles, tissues and organisms. As befits a conserved process, reductionism led to its study in microorganisms. Homotypic fusion of the vacuole of Saccharomyces cerevisiae is particularly accessible to study as vacuoles are readily visualized, there is a rapid and quantitative in vitro assay of vacuole fusion, and the genetics and genomics of this organism and of vacuole fusion are highly advanced. Recent progress is reviewed in the context of general questions in the membrane fusion field.
Topics: Intracellular Membranes; Membrane Fusion; Saccharomyces cerevisiae; Vacuoles
PubMed: 11889030
DOI: 10.1093/emboj/21.6.1241