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FEBS Letters Dec 2020Bacterial membrane proteins of the SbmA/BacA family are multi-solute transporters that mediate the uptake of structurally diverse hydrophilic molecules, including...
Bacterial membrane proteins of the SbmA/BacA family are multi-solute transporters that mediate the uptake of structurally diverse hydrophilic molecules, including aminoglycoside antibiotics and antimicrobial peptides. Some family members are full-length ATP-binding cassette (ABC) transporters, whereas other members are truncated homologues that lack the nucleotide-binding domains and thus mediate ATP-independent transport. A recent cryo-EM structure of the ABC transporter Rv1819c from Mycobacterium tuberculosis has shed light on the structural basis for multi-solute transport and has provided insight into the mechanism of transport. Here, we discuss how the protein architecture makes SbmA/BacA family transporters prone to inadvertent import of antibiotics and speculate on the question which physiological processes may benefit from multi-solute transport.
Topics: ATP-Binding Cassette Transporters; Anti-Bacterial Agents; Antigens, Bacterial; Bacterial Proteins; Biological Transport; Escherichia coli Proteins; Membrane Transport Proteins; Mycobacterium tuberculosis; Phosphoric Monoester Hydrolases; Substrate Specificity
PubMed: 32810294
DOI: 10.1002/1873-3468.13912 -
Nature Communications May 2022The SLC25 carrier family consists of 53 transporters that shuttle nutrients and co-factors across mitochondrial membranes. The family is highly redundant and their...
The SLC25 carrier family consists of 53 transporters that shuttle nutrients and co-factors across mitochondrial membranes. The family is highly redundant and their transport activities coupled to metabolic state. Here, we use a pooled, dual CRISPR screening strategy that knocks out pairs of transporters in four metabolic states - glucose, galactose, OXPHOS inhibition, and absence of pyruvate - designed to unmask the inter-dependence of these genes. In total, we screen 63 genes in four metabolic states, corresponding to 2016 single and pair-wise genetic perturbations. We recover 19 gene-by-environment (GxE) interactions and 9 gene-by-gene (GxG) interactions. One GxE interaction hit illustrates that the fitness defect in the mitochondrial folate carrier (SLC25A32) KO cells is genetically buffered in galactose due to a lack of substrate in de novo purine biosynthesis. GxG analysis highlights a buffering interaction between the iron transporter SLC25A37 (A37) and the poorly characterized SLC25A39 (A39). Mitochondrial metabolite profiling, organelle transport assays, and structure-guided mutagenesis identify A39 as critical for mitochondrial glutathione (GSH) import. Functional studies reveal that A39-mediated glutathione homeostasis and A37-mediated mitochondrial iron uptake operate jointly to support mitochondrial OXPHOS. Our work underscores the value of studying family-wide genetic interactions across different metabolic environments.
Topics: Clustered Regularly Interspaced Short Palindromic Repeats; Galactose; Glutathione; Homeostasis; Iron; Membrane Transport Proteins
PubMed: 35513392
DOI: 10.1038/s41467-022-30126-9 -
Cell Death & Disease Mar 2021Hypertrophic scar (HS) formation is a skin fibroproliferative disease that occurs following a cutaneous injury, leading to functional and cosmetic impairment. To date,...
Hypertrophic scar (HS) formation is a skin fibroproliferative disease that occurs following a cutaneous injury, leading to functional and cosmetic impairment. To date, few therapeutic treatments exhibit satisfactory outcomes. The mechanical force has been shown to be a key regulator of HS formation, but the underlying mechanism is not completely understood. The Piezo1 channel has been identified as a novel mechanically activated cation channel (MAC) and is reportedly capable of regulating force-mediated cellular biological behaviors. However, the mechanotransduction role of Piezo1 in HS formation has not been investigated. In this work, we found that Piezo1 was overexpressed in myofibroblasts of human and rat HS tissues. In vitro, cyclic mechanical stretch (CMS) increased Piezo1 expression and Piezo1-mediated calcium influx in human dermal fibroblasts (HDFs). In addition, Piezo1 activity promoted HDFs proliferation, motility, and differentiation in response to CMS. More importantly, intradermal injection of GsMTx4, a Piezo1-blocking peptide, protected rats from stretch-induced HS formation. Together, Piezo1 was shown to participate in HS formation and could be a novel target for the development of promising therapies for HS formation.
Topics: Animals; Apoptosis; Calcium Signaling; Case-Control Studies; Cell Differentiation; Cell Movement; Cell Proliferation; Cells, Cultured; Cicatrix, Hypertrophic; Disease Models, Animal; Fibroblasts; Humans; Intercellular Signaling Peptides and Proteins; Ion Channels; Male; Mechanotransduction, Cellular; Membrane Proteins; Membrane Transport Modulators; Rats, Sprague-Dawley; Skin; Spider Venoms; Rats
PubMed: 33649312
DOI: 10.1038/s41419-021-03481-6 -
Nature May 2020Toll-like receptors (TLRs) have a crucial role in the recognition of pathogens and initiation of immune responses. Here we show that a previously uncharacterized protein...
Toll-like receptors (TLRs) have a crucial role in the recognition of pathogens and initiation of immune responses. Here we show that a previously uncharacterized protein encoded by CXorf21-a gene that is associated with systemic lupus erythematosus-interacts with the endolysosomal transporter SLC15A4, an essential but poorly understood component of the endolysosomal TLR machinery also linked to autoimmune disease. Loss of this type-I-interferon-inducible protein, which we refer to as 'TLR adaptor interacting with SLC15A4 on the lysosome' (TASL), abrogated responses to endolysosomal TLR agonists in both primary and transformed human immune cells. Deletion of SLC15A4 or TASL specifically impaired the activation of the IRF pathway without affecting NF-κB and MAPK signalling, which indicates that ligand recognition and TLR engagement in the endolysosome occurred normally. Extensive mutagenesis of TASL demonstrated that its localization and function relies on the interaction with SLC15A4. TASL contains a conserved pLxIS motif (in which p denotes a hydrophilic residue and x denotes any residue) that mediates the recruitment and activation of IRF5. This finding shows that TASL is an innate immune adaptor for TLR7, TLR8 and TLR9 signalling, revealing a clear mechanistic analogy with the IRF3 adaptors STING, MAVS and TRIF. The identification of TASL as the component that links endolysosomal TLRs to the IRF5 transcription factor via SLC15A4 provides a mechanistic explanation for the involvement of these proteins in systemic lupus erythematosus.
Topics: Amino Acid Motifs; Animals; Female; Humans; Immunity, Innate; Interferon Regulatory Factors; Interferon Type I; Intracellular Signaling Peptides and Proteins; Lupus Erythematosus, Systemic; Lysosomes; Male; Membrane Transport Proteins; Nerve Tissue Proteins; Protein Binding; Signal Transduction; Toll-Like Receptor 7; Toll-Like Receptor 8; Toll-Like Receptor 9
PubMed: 32433612
DOI: 10.1038/s41586-020-2282-0 -
Science Advances Apr 2021Accumulating evidence shows that nervous system governs host immune responses; however, how γ-aminobutyric acid (GABA)ergic system shapes the function of innate immune...
Accumulating evidence shows that nervous system governs host immune responses; however, how γ-aminobutyric acid (GABA)ergic system shapes the function of innate immune cells is poorly defined. Here, we demonstrate that GABA transporter (GAT2) modulates the macrophage function. GAT2 deficiency lowers the production of interleukin-1β (IL-1β) in proinflammatory macrophages. Mechanistically, GAT2 deficiency boosts the betaine/S-adenosylmethionine (SAM)/hypoxanthine metabolic pathway to inhibit transcription factor KID3 expression through the increased DNA methylation in its promoter region. KID3 regulates oxidative phosphorylation (OXPHOS) via targeting the expression of OXPHOS-related genes and is also critical for NLRP3-ASC-caspase-1 complex formation. Likewise, GAT2 deficiency attenuates macrophage-mediated inflammatory responses in vivo, including lipopolysaccharide-induced sepsis, infection-induced pneumonia, and high-fat diet-induced obesity. Together, we propose that targeting GABAergic system (e.g., GABA transporter) could provide previously unidentified therapeutic opportunities for the macrophage-associated diseases.
Topics: Caspases; GABA Plasma Membrane Transport Proteins; Gene Expression; Interleukin-1beta; Lipopolysaccharides; Macrophages
PubMed: 33827820
DOI: 10.1126/sciadv.abe9274 -
International Journal of Molecular... Feb 2020This editorial aims to summarize the 19 scientific papers that contributed to this Special Issue.
This editorial aims to summarize the 19 scientific papers that contributed to this Special Issue.
Topics: Adaptor Proteins, Signal Transducing; Amino Acids; Biological Transport; Cationic Amino Acid Transporter 1; Glutamate Plasma Membrane Transport Proteins; Humans; Large Neutral Amino Acid-Transporter 1; Proteins
PubMed: 32059365
DOI: 10.3390/ijms21041212 -
The Journal of Biological Chemistry Jul 2022An ever-increasing number of proteins have been shown to translocate across various membranes of bacterial as well as eukaryotic cells in their folded states as a part... (Review)
Review
An ever-increasing number of proteins have been shown to translocate across various membranes of bacterial as well as eukaryotic cells in their folded states as a part of physiological and/or pathophysiological processes. Herein, we provide an overview of the systems/processes that are established or likely to involve the membrane translocation of folded proteins, such as protein export by the twin-arginine translocation system in bacteria and chloroplasts, unconventional protein secretion and protein import into the peroxisome in eukaryotes, and the cytosolic entry of proteins (e.g., bacterial toxins) and viruses into eukaryotes. We also discuss the various mechanistic models that have previously been proposed for the membrane translocation of folded proteins including pore/channel formation, local membrane disruption, membrane thinning, and transport by membrane vesicles. Finally, we introduce a newly discovered vesicular transport mechanism, vesicle budding and collapse, and present evidence that vesicle budding and collapse may represent a unifying mechanism that drives some (and potentially all) of folded protein translocation processes.
Topics: Bacteria; Bacterial Proteins; Eukaryota; Membrane Transport Proteins; Peroxisomes; Protein Folding; Protein Sorting Signals; Protein Transport; Twin-Arginine-Translocation System
PubMed: 35671825
DOI: 10.1016/j.jbc.2022.102107 -
Annual Review of Nutrition Aug 2023Amino acids derived from protein digestion are important nutrients for the growth and maintenance of organisms. Approximately half of the 20 proteinogenic amino acids... (Review)
Review
Amino acids derived from protein digestion are important nutrients for the growth and maintenance of organisms. Approximately half of the 20 proteinogenic amino acids can be synthesized by mammalian organisms, while the other half are essential and must be acquired from the nutrition. Absorption of amino acids is mediated by a set of amino acid transporters together with transport of di- and tripeptides. They provide amino acids for systemic needs and for enterocyte metabolism. Absorption is largely complete at the end of the small intestine. The large intestine mediates the uptake of amino acids derived from bacterial metabolism and endogenous sources. Lack of amino acid transporters and peptide transporter delays the absorption of amino acids and changes sensing and usage of amino acids by the intestine. This can affect metabolic health through amino acid restriction, sensing of amino acids, and production of antimicrobial peptides.
Topics: Humans; Animals; Biological Transport; Intestines; Amino Acids; Nutritional Status; Enterocytes; Antifibrinolytic Agents; Mammals
PubMed: 37285555
DOI: 10.1146/annurev-nutr-061121-094344 -
The Biochemical Journal Feb 2022Insulin rapidly stimulates GLUT4 translocation and glucose transport in fat and muscle cells. Signals from the occupied insulin receptor are translated into downstream...
Insulin rapidly stimulates GLUT4 translocation and glucose transport in fat and muscle cells. Signals from the occupied insulin receptor are translated into downstream signalling changes in serine/threonine kinases within timescales of seconds, and this is followed by delivery and accumulation of the glucose transporter GLUT4 at the plasma membrane. Kinetic studies have led to realisation that there are distinct phases of this stimulation by insulin. There is a rapid initial burst of GLUT4 delivered to the cell surface from a subcellular reservoir compartment and this is followed by a steady-state level of continuing stimulation in which GLUT4 recycles through a large itinerary of subcellular locations. Here, we provide an overview of the phases of insulin stimulation of GLUT4 translocation and the molecules that are currently considered to activate these trafficking steps. Furthermore, we suggest how use of new experimental approaches together with phospho-proteomic data may help to further identify mechanisms for activation of these trafficking processes.
Topics: Adipocytes; Animals; Cell Membrane; Glucose; Glucose Transporter Type 4; Humans; Insulin; Models, Biological; Muscle Cells; Phosphorylation; Protein Processing, Post-Translational; Protein Transport; Signal Transduction; Subcellular Fractions
PubMed: 35147164
DOI: 10.1042/BCJ20210073 -
Research in Microbiology 2019The CydDC family of ABC transporters export the low molecular weight thiols glutathione and cysteine to the periplasm of a variety of bacterial species. The CydDC... (Review)
Review
The CydDC family of ABC transporters export the low molecular weight thiols glutathione and cysteine to the periplasm of a variety of bacterial species. The CydDC complex has previously been shown to be important for disulfide folding, motility, respiration, and tolerance to nitric oxide and antibiotics. In addition, CydDC is thus far unique amongst ABC transporters in that it binds a haem cofactor that appears to modulate ATPase activity. CydDC has a diverse impact upon bacterial metabolism, growth, and virulence, and is of interest to those working on membrane transport mechanisms, redox biology, aerobic respiration, and stress sensing/tolerance during infection.
Topics: ATP-Binding Cassette Transporters; Adenosine Triphosphatases; Anti-Bacterial Agents; Biological Transport; Cysteine; Escherichia coli; Escherichia coli Proteins; Glutathione; Heme; Oxidation-Reduction; Periplasm
PubMed: 31279084
DOI: 10.1016/j.resmic.2019.06.003