-
Cell Reports Aug 2023Proton-dependent oligopeptide transporters (POTs) are promiscuous transporters of the major facilitator superfamily that constitute the main route of entry for a wide...
Proton-dependent oligopeptide transporters (POTs) are promiscuous transporters of the major facilitator superfamily that constitute the main route of entry for a wide range of dietary peptides and orally administrated peptidomimetic drugs. Given their clinical and pathophysiological relevance, several POT homologs have been studied extensively at the structural and molecular level. However, the molecular basis of recognition and transport of diverse peptide substrates has remained elusive. We present 14 X-ray structures of the bacterial POT DtpB in complex with chemically diverse di- and tripeptides, providing novel insights into the plasticity of the conserved central binding cavity. We analyzed binding affinities for more than 80 peptides and monitored uptake by a fluorescence-based transport assay. To probe whether all 8400 natural di- and tripeptides can bind to DtpB, we employed state-of-the-art molecular docking and machine learning and conclude that peptides with compact hydrophobic residues are the best DtpB binders.
Topics: Molecular Docking Simulation; Models, Molecular; Membrane Transport Proteins; Peptides
PubMed: 37467108
DOI: 10.1016/j.celrep.2023.112831 -
Molecular Pharmaceutics Jun 2023Drug interactions involving the inhibition of hepatic organic anion transporting polypeptides (OATPs) 1B1 and OATP1B3 are considered important. Therefore, we sought to...
Drug interactions involving the inhibition of hepatic organic anion transporting polypeptides (OATPs) 1B1 and OATP1B3 are considered important. Therefore, we sought to study various sulfated bile acids (BA-S) as potential clinical OATP1B1/3 biomarkers. It was determined that BA-S [e.g., glycochenodeoxycholic acid 3-O-sulfate (GCDCA-S) and glycodeoxycholic acid 3-O-sulfate (GDCA-S)] are substrates of OATP1B1, OATP1B3, and sodium-dependent taurocholic acid cotransporting polypeptide (NTCP) transfected into human embryonic kidney 293 cells, with minimal uptake evident for other solute carriers (SLCs) like OATP2B1, organic anion transporter 2, and organic cation transporter 1. It was also shown that BA-S uptake by plated human hepatocytes (PHH) was inhibited (≥96%) by a pan-SLC inhibitor (rifamycin SV), and there was greater inhibition (≥77% versus ≤12%) with rifampicin (OATP1B1/3-selective inhibitor) than a hepatitis B virus myristoylated-preS1 peptide (NTCP-selective inhibitor). Estrone 3-sulfate was also used as an OATP1B1-selective inhibitor. In this instance, greater inhibition was observed with GDCA-S (76%) than GCDCA-S (52%). The study was expanded to encompass the measurement of GCDCA-S and GDCA-S in plasma of genotyped subjects. The geometric mean GDCA-S concentration was 2.6-fold (90% confidence interval 1.6, 4.3; = 2.1 × 10) and 1.3-fold (1.1, 1.7; = 0.001) higher in individuals homozygous and heterozygous for the c.521T > C loss-of-function allele, respectively. For GCDCA-S, no significant difference was noted [1.2-fold (0.8, 1.7; = 0.384) and 0.9-fold (0.8, 1.1; = 0.190), respectively]. This supported the in vitro data indicating that GDCA-S is a more OATP1B1-selective substrate (versus GCDCA-S). It is concluded that GCDCA-S and GDCA-S are viable plasma-based OATP1B1/3 biomarkers, but they are both less OATP1B1-selective when compared to their corresponding 3-O-glucuronides (GCDCA-3G and GDCA-3G). Additional studies are needed to determine their utility versus more established biomarkers, such as coproporphyrin I, for assessing inhibitors with different OATP1B1 (versus OATP1B3) inhibition signatures.
Topics: Humans; Organic Anion Transporters; Sulfates; Solute Carrier Organic Anion Transporter Family Member 1B3; Liver-Specific Organic Anion Transporter 1; Bile Acids and Salts; Biological Transport; Biomarkers; Organic Anion Transporters, Sodium-Independent
PubMed: 37134201
DOI: 10.1021/acs.molpharmaceut.3c00040 -
Research in Microbiology 2019Microcins and bacteriocins are ribosomally-synthesized defence peptides produced by Gram-negative and -positive bacteria to target competitors in their niche. Some of... (Review)
Review
Microcins and bacteriocins are ribosomally-synthesized defence peptides produced by Gram-negative and -positive bacteria to target competitors in their niche. Some of them carry posttranslational modifications established by dedicated enzymes. To protect themselves from their own toxic peptides, bacteria use dedicated immunity proteins or expel the toxin using ATP-binding cassette (ABC) transporters. In this last case, this immunity function is associated to export of the antimicrobial peptide out of the producing cells for targeting their competitors. Here we review the characteristics of these ABC-exporters and the mechanisms they use that unexpectedly cover from high promiscuity to high specificity or ensure another function concomitantly.
Topics: ATP-Binding Cassette Transporters; Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Bacteriocins; Biological Transport; Drug Resistance, Bacterial; Gram-Negative Bacteria; Gram-Positive Bacteria
PubMed: 31401108
DOI: 10.1016/j.resmic.2019.07.002 -
Biochimica Et Biophysica Acta.... Feb 2020Gestational diabetes mellitus (GDM) is a disease of pregnancy associated with maternal and foetal hyperglycaemia and altered foetoplacental vascular function. Human... (Review)
Review
Gestational diabetes mellitus (GDM) is a disease of pregnancy associated with maternal and foetal hyperglycaemia and altered foetoplacental vascular function. Human foetoplacental microvascular and macrovascular endothelium from GDM pregnancy show increased maximal l-arginine transport capacity via the human cationic amino acid transporter 1 (hCAT-1) isoform and nitric oxide (NO) synthesis by the endothelial NO synthase (eNOS). These alterations are paralleled by lower maximal transport activity of the endogenous nucleoside adenosine via the human equilibrative nucleoside transporter 1 (hENT1) and activation of adenosine receptors. A causal relationship has been described for adenosine-activation of A adenosine receptors, hCAT-1, and eNOS activity (i.e. the Adenosine/l-Arginine/Nitric Oxide, ALANO, signalling pathway). Insulin restores these alterations in GDM via activation of insulin receptor A (IR-A) form in the macrovascular but IR-A and IR-B forms in the microcirculation of the human placenta. Adipokines are secreted from adipocytes influencing the foetoplacental metabolic and vascular function. Various adipokines are dysregulated in GDM, with adiponectin and leptin playing major roles. Abnormal plasma concentration of these adipokines and the activation or their receptors are involved in the pathophysiology of GDM. However, involvement of adipokines, adenosine, and insulin receptors and membrane transporters in the aetiology of this disease of pregnancy is unknown. This review focuses on the pathophysiology of insulin and adenosine receptors and l-arginine and adenosine membranes transporters giving an overview of the key adipokines leptin and adiponectin in the foetoplacental vasculature in GDM. This article is part of a Special Issue entitled: Membrane Transporters and Receptors in Pregnancy Metabolic Complications edited by Luis Sobrevia.
Topics: Adenosine; Adipokines; Antigens, CD; Arginine; Biological Transport; Cationic Amino Acid Transporter 1; Diabetes, Gestational; Endothelium; Endothelium, Vascular; Equilibrative Nucleoside Transporter 1; Female; GTPase-Activating Proteins; Humans; Insulin; Nitric Oxide; Nitric Oxide Synthase Type III; Placenta; Pregnancy; Protein Isoforms; Receptor, Insulin; Receptors, Adipokine; Receptors, Purinergic P1; Signal Transduction
PubMed: 30660686
DOI: 10.1016/j.bbadis.2018.12.021 -
Yakugaku Zasshi : Journal of the... 2021The blood-brain barrier (BBB) consists of brain capillary endothelial cells linked by tight junctions and serves to regulate the transfer of endogenous compounds and... (Review)
Review
The blood-brain barrier (BBB) consists of brain capillary endothelial cells linked by tight junctions and serves to regulate the transfer of endogenous compounds and xenobiotics between the circulating blood and brain interstitial fluid. We have developed a methodology to characterize brain-to-blood efflux transport in vivo, using the Brain Efflux Index and an in vitro culture model of the BBB, i.e., a conditionally immortalized cell line of the neurovascular unit. Employing these methods, we showed that the BBB plays an important role in protecting the brain by transporting neurotransmitters, neuromodulators, metabolites, uremic toxins, and xenobiotics together with atrial natriuretic peptide from the brain interstitial fluid to the circulating blood. We also developed a highly selective, sensitive LC-MS/MS method for simultaneous protein quantification. We found significant species differences in the expression amounts of various BBB transporter proteins among mice, rats, marmosets, cynomolgus monkeys, and humans. Among transporter proteins at the BBB, multidrug resistance protein 1 (Mdr1/Abcb1) is known to generate a concentration gradient of unbound substrate drugs between the blood and brain. Based on measurements of the intrinsic efflux transport rate of Mdr1 and the protein expression amounts of Mdr1 in mouse brain capillaries and Mdr1-expressing cell lines, we predicted the unbound drug concentration gradients of 7 drugs in the mouse brain in vivo. This was the first successful prediction of in vivo drug transport activity from in vitro experimental data and transporter protein concentration in tissues. This methodology and findings should greatly advance central nervous system barrier research.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Biological Transport; Blood-Brain Barrier; Brain; Cell Line; Chromatography, Liquid; Humans; Membrane Transport Proteins; Mice; Neurotransmitter Agents; Proteomics; Rats; Tandem Mass Spectrometry; Xenobiotics
PubMed: 33790111
DOI: 10.1248/yakushi.20-00232 -
Structure (London, England : 1993) Jul 2022Mammalian peptide transporters, PepT1 and PepT2, mediate uptake of small peptides and are essential for their absorption. PepT also mediates absorption of many drugs and...
Mammalian peptide transporters, PepT1 and PepT2, mediate uptake of small peptides and are essential for their absorption. PepT also mediates absorption of many drugs and prodrugs to enhance their bioavailability. PepT has twelve transmembrane (TM) helices that fold into an N-terminal domain (NTD, TM1-6) and a C-terminal domain (CTD, TM7-12) and has a large extracellular domain (ECD) between TM9-10. It is well recognized that peptide transport requires movements of the NTD and CTD, but the role of the ECD in PepT1 remains unclear. Here we report the structure of horse PepT1 encircled in lipid nanodiscs and captured in the inward-open apo conformation. The structure shows that the ECD bridges the NTD and CTD by interacting with TM1. Deletion of ECD or mutations to the ECD-TM1 interface impairs the transport activity. These results demonstrate an important role of ECD in PepT1 and enhance our understanding of the transport mechanism in PepT1.
Topics: Animals; Biological Transport; Horses; Mammals; Molecular Conformation; Peptide Transporter 1; Peptides; Symporters
PubMed: 35580608
DOI: 10.1016/j.str.2022.04.011 -
The EMBO Journal Jun 2020Multiple mitochondrial quality control pathways exist to maintain the health of mitochondria and ensure cell homeostasis. Here, we investigate the role of the endosomal...
Multiple mitochondrial quality control pathways exist to maintain the health of mitochondria and ensure cell homeostasis. Here, we investigate the role of the endosomal adaptor Tollip during the mitochondrial stress response and identify its interaction and colocalisation with the Parkinson's disease-associated E3 ubiquitin ligase Parkin. The interaction between Tollip and Parkin is dependent on the ubiquitin-binding CUE domain of Tollip, but independent of Tom1 and mitophagy. Interestingly, this interaction is independent of Parkin mitochondrial recruitment and ligase activity but requires an intact ubiquitin-like (UBL) domain. Importantly, Tollip regulates Parkin-dependent endosomal trafficking of a discrete subset of mitochondrial-derived vesicles (MDVs) to facilitate delivery to lysosomes. Retromer function and an interaction with Tom1 allow Tollip to facilitate late endosome/lysosome trafficking in response to mitochondrial stress. We find that upregulation of TOM20-positive MDVs upon mitochondrial stress requires Tollip interaction with ubiquitin, endosomal membranes and Tom1 to ensure their trafficking to the lysosomes. Thus, we conclude that Tollip, via an association with Parkin, is an essential coordinator to sort damaged mitochondrial-derived cargo to the lysosomes.
Topics: Endosomes; HEK293 Cells; HeLa Cells; Humans; Intracellular Signaling Peptides and Proteins; Lysosomes; Membrane Transport Proteins; Mitochondria; Mitochondrial Precursor Protein Import Complex Proteins; Protein Transport; Receptors, Cell Surface; Ubiquitin-Protein Ligases
PubMed: 32311122
DOI: 10.15252/embj.2019102539 -
Tuberculosis (Edinburgh, Scotland) Sep 2016Mycobacteria produce a large variety of surface-exposed lipids with unusual structures. Some of these compounds are ubiquitously present in mycobacteria and play an... (Review)
Review
Mycobacteria produce a large variety of surface-exposed lipids with unusual structures. Some of these compounds are ubiquitously present in mycobacteria and play an important role in the structural organization of the cell envelope, while others are species-specific. The biosynthesis of most of these lipids requires modular polyketide synthases (PKS) or non-ribosomal peptide synthetases (NRPS) that are intracellular, suggesting that the assembly of these compounds takes place in the cytosolic compartment or near the inner leaflet of the plasma membrane. The molecular mechanisms that mediate the export of these lipid components across the cell envelope remain poorly understood. Mycobacterial membrane protein Large (MmpL) transporters, a subclass of Resistance-Nodulation-Cell Division (RND) transporters, appear to play a major role in this process, acting as scaffold proteins that couple lipid synthesis and transport. Recent studies have shown that this family of transporters also contributes to siderophore secretion in Mycobacterium tuberculosis. The goal of this review is to provide the most recent advances in our understanding of the molecular mechanisms involved in lipid and siderophore transport mediated by MmpL transporters.
Topics: Bacterial Proteins; Biological Transport; Cell Wall; Genes, Bacterial; Humans; Membrane Lipids; Membrane Transport Proteins; Mycobacterium; Mycobacterium tuberculosis; Myelin Proteolipid Protein; Siderophores; Structure-Activity Relationship
PubMed: 27553408
DOI: 10.1016/j.tube.2016.06.004 -
Current Biology : CB Apr 2024In this Quick guide, Palmer and Berks introduce the twin-arginine translocation (Tat) systems. Tats are found in a variety of microbes and microbe-derived organelles,...
In this Quick guide, Palmer and Berks introduce the twin-arginine translocation (Tat) systems. Tats are found in a variety of microbes and microbe-derived organelles, and are known to translocate folded substrate proteins across biological membranes.
Topics: Membrane Transport Proteins; Escherichia coli Proteins; Twin-Arginine-Translocation System; Cell Membrane; Arginine; Protein Transport; Protein Sorting Signals; Bacterial Proteins
PubMed: 38593766
DOI: 10.1016/j.cub.2024.02.039 -
Vitamins and Hormones 2015Neuronal norepinephrine (NE) uptake is a crucial step in noradrenergic neurotransmission that regulates NE concentration in the synaptic cleft. It is a key mechanism... (Review)
Review
Neuronal norepinephrine (NE) uptake is a crucial step in noradrenergic neurotransmission that regulates NE concentration in the synaptic cleft. It is a key mechanism mediated by the NE transporter (NET) which takes the neurotransmitter into the presynaptic neuron terminal or the adrenal medulla chromaffin cell. The activity of NET is short and long terms modulated by phosphorylation mediated by protein kinases A, C, and G and calcium-calmodulin-dependent protein kinase, whereas the transporter availability at the cell surface is regulated by glycosylation. Several neuropeptides like angiotensins II, III, and 1-7, bradykinin, natriuretic peptides, as well as endothelins (ETs) regulate a wide variety of biological effects, including noradrenergic transmission and in particular neuronal NE uptake. Diverse reports, including studies from our laboratory, show that ETs differentially modulate the activity and expression of NET not only in normal conditions but also in diverse cardiovascular diseases such as congestive heart failure and hypertension. Current literature supports a key role for the interaction between ETs and NE in maintaining neurotransmission homeostasis and further suggests that this interaction may represent a potential therapeutic target for various diseases, particularly hypertension.
Topics: Animals; Biological Transport; Cardiovascular Diseases; Endothelins; Homeostasis; Humans; Norepinephrine; Norepinephrine Plasma Membrane Transport Proteins; Signal Transduction
PubMed: 25817875
DOI: 10.1016/bs.vh.2014.12.013