51
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Wang CY, Liu S, Xie XN, Tan ZR. Regulation profile of the intestinal peptide transporter 1 (PepT1). DRUG DESIGN DEVELOPMENT AND THERAPY 2017; 11:3511-3517. [PMID: 29263649 PMCID: PMC5726373 DOI: 10.2147/dddt.s151725] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The intestinal peptide transporter 1 (PepT1) was first identified in 1994. It plays a crucial role in the absorption of small peptides including not only >400 different dipeptides and 8,000 tripeptides digested from dietary proteins but also a repertoire of structurally related compounds and drugs. Owing to its critical role in the bioavailability of peptide-like drugs, such as the anti-cancer agents and anti-virus drug, PepT1 is increasingly becoming a striking prodrug-designing target. Therefore, the understanding of PepT1 gene regulation is of great importance both for dietary adaptation and for clinical drug treatment. After decades of research, it has been recognized that PepT1 could be regulated at the transcriptional and post-transcriptional levels by numerous factors. Therefore, the present review intends to summarize the progress made in the regulation of PepT1 and provide insights into the PepT1's potential in clinical aspects of nutritional and drug therapies.
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Affiliation(s)
- Chun-Yang Wang
- Department of Clinical Pharmacology, Xiangya Hospital, Xiangya School of Medicine, Central South University.,Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha, Hunan, People's Republic of China
| | - Shu Liu
- Department of Clinical Pharmacology, Xiangya Hospital, Xiangya School of Medicine, Central South University.,Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha, Hunan, People's Republic of China
| | - Xiao-Nv Xie
- Department of Clinical Pharmacology, Xiangya Hospital, Xiangya School of Medicine, Central South University.,Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha, Hunan, People's Republic of China
| | - Zhi-Rong Tan
- Department of Clinical Pharmacology, Xiangya Hospital, Xiangya School of Medicine, Central South University.,Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha, Hunan, People's Republic of China
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52
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Abstract
POT transporters represent an evolutionarily well-conserved family of proton-coupled transport systems in biology. An unusual feature of the family is their ability to couple the transport of chemically diverse ligands to an inwardly directed proton electrochemical gradient. For example, in mammals, fungi, and bacteria they are predominantly peptide transporters, whereas in plants the family has diverged to recognize nitrate, plant defense compounds, and hormones. Although recent structural and biochemical studies have identified conserved sites of proton binding, the mechanism through which transport is coupled to proton movement remains enigmatic. Here we show that different POT transporters operate through distinct proton-coupled mechanisms through changes in the extracellular gate. A high-resolution crystal structure reveals the presence of ordered water molecules within the peptide binding site. Multiscale molecular dynamics simulations confirm proton transport occurs through these waters via Grotthuss shuttling and reveal that proton binding to the extracellular side of the transporter facilitates a reorientation from an inward- to outward-facing state. Together these results demonstrate that within the POT family multiple mechanisms of proton coupling have likely evolved in conjunction with variation of the extracellular gate.
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53
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Prabhala BK, Aduri NG, Sharma N, Shaheen A, Sharma A, Iqbal M, Hansen PR, Brasen C, Gajhede M, Rahman M, Mirza O. The prototypical proton-coupled oligopeptide transporter YdgR from Escherichia coli facilitates chloramphenicol uptake into bacterial cells. J Biol Chem 2017; 293:1007-1017. [PMID: 29150447 DOI: 10.1074/jbc.m117.805960] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 11/07/2017] [Indexed: 11/06/2022] Open
Abstract
Chloramphenicol (Cam) is a broad-spectrum antibiotic used to combat bacterial infections in humans and animals. Cam export from bacterial cells is one of the mechanisms by which pathogens resist Cam's antibacterial effects, and several different proteins are known to facilitate this process. However, to date no report exists on any specific transport protein that facilitates Cam uptake. The proton-coupled oligopeptide transporter (POT) YdgR from Escherichia coli is a prototypical member of the POT family, functioning in proton-coupled uptake of di- and tripeptides. By following bacterial growth and conducting LC-MS-based assays we show here that YdgR facilitates Cam uptake. Some YdgR variants displaying reduced peptide uptake also exhibited reduced Cam uptake, indicating that peptides and Cam bind YdgR at similar regions. Homology modeling of YdgR, Cam docking, and mutational studies suggested a binding mode that resembles that of Cam binding to the multidrug resistance transporter MdfA. To our knowledge, this is the first report of Cam uptake into bacterial cells mediated by a specific transporter protein. Our findings suggest a specific bacterial transporter for drug uptake that might be targeted to promote greater antibiotic influx to increase cytoplasmic antibiotic concentration for enhanced cytotoxicity.
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Affiliation(s)
- Bala K Prabhala
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Nanda G Aduri
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Neha Sharma
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Aqsa Shaheen
- the Health Biotechnology Divisions, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
| | - Arpan Sharma
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Mazhar Iqbal
- the Health Biotechnology Divisions, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
| | - Paul R Hansen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Christoffer Brasen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Michael Gajhede
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Moazur Rahman
- the Health Biotechnology Divisions, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
| | - Osman Mirza
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
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54
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Colas C, Masuda M, Sugio K, Miyauchi S, Hu Y, Smith DE, Schlessinger A. Chemical Modulation of the Human Oligopeptide Transporter 1, hPepT1. Mol Pharm 2017; 14:4685-4693. [PMID: 29111754 DOI: 10.1021/acs.molpharmaceut.7b00775] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In humans, peptides derived from dietary proteins and peptide-like drugs are transported via the proton-dependent oligopeptide transporter hPepT1 (SLC15A1). hPepT1 is located across the apical membranes of the small intestine and kidney, where it serves as a high-capacity low-affinity transporter of a broad range of di- and tripeptides. hPepT1 is also overexpressed in the colon of inflammatory bowel disease (IBD) patients, where it mediates the transport of harmful peptides of bacterial origin. Therefore, hPepT1 is a drug target for prodrug substrates interacting with intracellular proteins or inhibitors blocking the transport of toxic bacterial products. In this study, we construct multiple structural models of hPepT1 representing different conformational states that occur during transport and inhibition. We then identify and characterize five ligands of hPepT1 using computational methods, such as virtual screening and QM-polarized ligand docking (QPLD), and experimental testing with uptake kinetic measurements and electrophysiological assays. Our results improve our understanding of the substrate and inhibitor specificity of hPepT1. Furthermore, the newly discovered ligands exhibit unique chemotypes, providing a framework for developing tool compounds with optimal intestinal absorption as well as future IBD therapeutics against this emerging drug target.
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Affiliation(s)
- Claire Colas
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
| | - Masayuki Masuda
- Faculty of Pharmaceutical Sciences, Toho University , Funabashi, Chiba 274-8510, Japan
| | - Kazuaki Sugio
- Faculty of Pharmaceutical Sciences, Toho University , Funabashi, Chiba 274-8510, Japan
| | - Seiji Miyauchi
- Faculty of Pharmaceutical Sciences, Toho University , Funabashi, Chiba 274-8510, Japan
| | - Yongjun Hu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - David E Smith
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
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55
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Braun C, Sakamoto A, Fuchs H, Ishiguro N, Suzuki S, Cui Y, Klinder K, Watanabe M, Terasaki T, Sauer A. Quantification of Transporter and Receptor Proteins in Dog Brain Capillaries and Choroid Plexus: Relevance for the Distribution in Brain and CSF of Selected BCRP and P-gp Substrates. Mol Pharm 2017; 14:3436-3447. [PMID: 28880093 DOI: 10.1021/acs.molpharmaceut.7b00449] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Transporters at the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) play a pivotal role as gatekeepers for efflux or uptake of endogenous and exogenous molecules. The protein expression of a number of them has already been determined in the brains of rodents, nonhuman primates, and humans using quantitative targeted absolute proteomics (QTAP). The dog is an important animal model for drug discovery and development, especially for safety evaluations. The purpose of the present study was to clarify the relevance of the transporter protein expression for drug distribution in the dog brain and CSF. We used QTAP to examine the protein expression of 17 selected transporters and receptors at the dog BBB and BCSFB. For the first time, we directly linked the expression of two efflux transporters, P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), to regional brain and CSF distribution using specific substrates. Two cocktails, each containing one P-gp substrate (quinidine or apafant) and one BCRP substrate (dantrolene or daidzein) were infused intravenously prior to collection of the brain. Transporter expression varied only slightly between the capillaries of different brain regions and did not result in region-specific distribution of the investigated substrates. There were, however, distinct differences between brain capillaries and choroid plexus. Largest differences were observed for BCRP and P-gp: both were highly expressed in brain capillaries, but no BCRP and only low amounts of P-gp were detected in the choroid plexus. Kp,uu,brain and Kp,uu,CSF of both P-gp substrates were indicative of drug efflux. Also, Kp,uu,brain for the BCRP substrates was low. In contrast, Kp,uu,CSF for both BCRP substrates was close to unity, resulting in Kp,uu,CSF/Kp,uu,brain ratios of 7 and 8, respectively. We conclude that the drug transporter expression profiles differ between the BBB and BCSFB in dogs, that there are species differences in the expression profiles, and that CSF is not a suitable surrogate for unbound brain concentrations of BCRP substrates in dogs.
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Affiliation(s)
- Clemens Braun
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG , 88397 Biberach an der Riss, Germany
| | - Atsushi Sakamoto
- Kobe Pharma Research Institute, Nippon Boehringer Ingelheim Co., Ltd. , Kobe 650-0046, Japan
| | - Holger Fuchs
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG , 88397 Biberach an der Riss, Germany
| | - Naoki Ishiguro
- Kobe Pharma Research Institute, Nippon Boehringer Ingelheim Co., Ltd. , Kobe 650-0046, Japan
| | - Shinobu Suzuki
- Kobe Pharma Research Institute, Nippon Boehringer Ingelheim Co., Ltd. , Kobe 650-0046, Japan
| | - Yunhai Cui
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG , 88397 Biberach an der Riss, Germany
| | - Klaus Klinder
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG , 88397 Biberach an der Riss, Germany
| | - Michitoshi Watanabe
- Proteomedix Frontiers Co., Ltd , T-Biz, 6-6-40 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.,Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences, Tohoku University , 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Tetsuya Terasaki
- Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences, Tohoku University , 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Achim Sauer
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG , 88397 Biberach an der Riss, Germany
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56
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Charge and hydrophobicity of casein peptides influence transepithelial transport and bioavailability. Food Chem 2017; 245:646-652. [PMID: 29287421 DOI: 10.1016/j.foodchem.2017.09.032] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/04/2017] [Accepted: 09/06/2017] [Indexed: 11/20/2022]
Abstract
Antioxidant casein peptides were separated by SP-Sephadex C-25 and C 18 columns. The transepithelial transport and bioavailability including the transport ratio and the remaining ratios of antioxidant activity (RRAA) of these peptide absorbates, were then investigated using a Caco-2 cell monolayer. The results indicate that both the negatively charged peptide fractions (CF1, CF2 and CF3) and the more hydrophilic fraction (HF1) were mainly transported via PepT1 and paracellular routes. The positively charged fractions (CF4 and CF5) and hydrophobic fractions (HF2, HF3 and HF4) were transported via PepT1 and transcytosis. The strongly negatively charged and more hydrophobic fractions showed a higher transport ratio, which ranged from 9.5 to 12.5%; however, the transport ratio of positively charged and hydrophilic fractions ranged from 4.0 to 8.5%. The positively charged and hydrophilic fractions showed a higher RRAA.
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57
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Mittal S, Shukla D. Predicting Optimal DEER Label Positions to Study Protein Conformational Heterogeneity. J Phys Chem B 2017; 121:9761-9770. [DOI: 10.1021/acs.jpcb.7b04785] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Shriyaa Mittal
- Center
for Biophysics and Quantitative Biology and ‡Department of Chemical and Biomolecular
Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Diwakar Shukla
- Center
for Biophysics and Quantitative Biology and ‡Department of Chemical and Biomolecular
Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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58
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Gong Y, Zhang J, Wu X, Wang T, Zhao J, Yao Z, Zhang Q, Liu X, Jian X. Specific expression of proton-coupled oligopeptide transporter 1 in primary hepatocarcinoma-a novel strategy for tumor-targeted therapy. Oncol Lett 2017; 14:4158-4166. [PMID: 28943923 PMCID: PMC5592876 DOI: 10.3892/ol.2017.6724] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 05/16/2017] [Indexed: 12/13/2022] Open
Abstract
Proton-coupled oligopeptide transporter 1 (PEPT1) is a membrane protein which expressed predominantly in intestine and recognized as the target of dietary nutrients (di/tripeptide) or peptidomimetic drug for delivery. The information on the existence of PEPT1 in carcinomas were limited. Our study aimed to investigate the expression profile and transport activity of PEPT1 both in human hepatocarcinoma tissues and cell lines. Western blotting and an immunofluorescence assay revealed the high level of PEPT1 protein expression in hepatocarcinoma Bel-7402, SMMC-7721, HepG2, HEP3B, SK-HEP-1 cell lines. Quantitative real time PCR showed the mRNA expression of PEPT1 in Bel-7402, SMMC-7721, HepG2, HEP3B, SK-HEP-1 cells. High level PEPT1 expression in hepatocarcinoma patient samples were observed by Immunohistology and showed a significant correlation between protein level and pathological grade. Functional activities were also studied using D-Ala-Lys-AMCA (a substrate of peptide transporter) in above five hepatocarcinoma cell lines. The uptake tests performed by fluorescent microscopy suggested that PEPT1 can transport both D-Ala-Lys-AMCA into the hepatocarcinoma cells and the uptake can be competitively inhibited by three PEPT1 substrates (Gly-sar, Gly-gln and Glyglygly). In conclusion, our findings provided the novel information on the expression and function of PEPT1 in human hepatocarcinoma and expanded the potential values for tumor specific drug delivery.
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Affiliation(s)
- Yanxia Gong
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China.,Department of Gastroenterology, Tianjin Nankai Hospital, Tianjin 300100, P.R. China
| | - Jie Zhang
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Xiang Wu
- Central Laboratory, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Tao Wang
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Jia Zhao
- Clinical Laboratory, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Zhi Yao
- Department of Immunology, School of Basic Medical Science, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Qingyu Zhang
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Xi Liu
- Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
| | - Xu Jian
- Central Laboratory, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
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59
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Li H, Yu M, Du XQ, Wang ZF, Wu WH, Quintero FJ, Jin XH, Li HD, Wang Y. NRT1.5/NPF7.3 Functions as a Proton-Coupled H +/K + Antiporter for K + Loading into the Xylem in Arabidopsis. THE PLANT CELL 2017; 29:2016-2026. [PMID: 28739644 PMCID: PMC5590498 DOI: 10.1105/tpc.16.00972] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 07/07/2017] [Accepted: 07/22/2017] [Indexed: 05/02/2023]
Abstract
Potassium and nitrogen are essential macronutrients for plant growth and have a positive impact on crop yield. Previous studies have indicated that the absorption and translocation of K+ and NO3- are correlated with each other in plants; however, the molecular mechanism that coordinates K+ and NO3- transport remains unknown. In this study, using a forward genetic approach, we isolated a low-K+-sensitive Arabidopsis thaliana mutant, lks2, that showed a leaf chlorosis phenotype under low-K+ conditions. LKS2 encodes the transporter NRT1.5/NPF7.3, a member of the NRT1/PTR (Nitrate Transporter 1/Peptide Transporter) family. The lks2/nrt1.5 mutants exhibit a remarkable defect in both K+ and NO3- translocation from root to shoot, especially under low-K+ conditions. This study demonstrates that LKS2 (NRT1.5) functions as a proton-coupled H+/K+ antiporter. Proton gradient can promote NRT1.5-mediated K+ release out of root parenchyma cells and facilitate K+ loading into the xylem. This study reveals that NRT1.5 plays a crucial role in K+ translocation from root to shoot and is also involved in the coordination of K+/NO3- distribution in plants.
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Affiliation(s)
- Hong Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Miao Yu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xin-Qiao Du
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Zhi-Fang Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Francisco J Quintero
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas, 41092 Sevilla, Spain
| | - Xue-Hua Jin
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Hao-Dong Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
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60
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Hong M. Biochemical studies on the structure-function relationship of major drug transporters in the ATP-binding cassette family and solute carrier family. Adv Drug Deliv Rev 2017; 116:3-20. [PMID: 27317853 DOI: 10.1016/j.addr.2016.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 12/21/2022]
Abstract
Human drug transporters often play key roles in determining drug accumulation within cells. Their activities are often directly related to therapeutic efficacy, drug toxicity as well as drug-drug interactions. However, the progress for interpretation of their crystal structures is relatively slow. Hence, conventional biochemical studies together with computer modeling became useful manners to reveal essential structures of these membrane proteins. Over the years, quite a few structure-function relationship information had been obtained for members of the two major transporter families: the ATP-binding cassette family and the solute carrier family. Critical structural features of drug transporters include transmembrane domains, post-translational modification sites and domains for cell surface assembly and protein-protein interactions. Alterations at these important sites may affect protein stability, trafficking to the plasma membrane and/or ability of transporters to interact with substrates.
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61
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Symmetry and Structure in the POT Family of Proton Coupled Peptide Transporters. Symmetry (Basel) 2017. [DOI: 10.3390/sym9060085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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62
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Stelzl T, Geillinger-Kästle KE, Stolz J, Daniel H. Glycans in the intestinal peptide transporter PEPT1 contribute to function and protect from proteolysis. Am J Physiol Gastrointest Liver Physiol 2017; 312:G580-G591. [PMID: 28336547 DOI: 10.1152/ajpgi.00343.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 03/16/2017] [Accepted: 03/17/2017] [Indexed: 01/31/2023]
Abstract
Despite the fact that many membrane proteins carry extracellular glycans, little is known about whether the glycan chains also affect protein function. We recently demonstrated that the proton-coupled oligopeptide transporter 1 (PEPT1) in the intestine is glycosylated at six asparagine residues (N50, N406, N439, N510, N515, and N532). Mutagenesis-induced disruption of the individual N-glycosylation site N50, which is highly conserved among mammals, was detected to significantly enhance the PEPT1-mediated inward transport of peptides. Here, we show that for the murine protein the inhibition of glycosylation at sequon N50 by substituting N50 with glutamine, lysine, or cysteine or by replacing S52 with alanine equally altered PEPT1 transport kinetics in oocytes. Furthermore, we provide evidence that the uptake of [14C]glycyl-sarcosine in immortalized murine small intestinal (MODE-K) or colonic epithelial (PTK-6) cells stably expressing the PEPT1 transporter N50Q is also significantly increased relative to the wild-type protein. By using electrophysiological recordings and tracer flux studies, we further demonstrate that the rise in transport velocity observed for PEPT1 N50Q is bidirectional. In line with these findings, we show that attachment of biotin derivatives, comparable in weight with two to four monosaccharides, to the PEPT1 N50C transporter slows down the transport velocity. In addition, our experiments provide strong evidence that glycosylation of PEPT1 confers resistance against proteolytic cleavage by proteinase K, whereas a remarkable intrinsic stability against trypsin, even in the absence of N-linked glycans, was detected.NEW & NOTEWORTHY This study highlights the role of N50-linked glycans in modulating the bidirectional transport activity of the murine peptide transporter PEPT1. Electrophysiological and tracer flux measurements in Xenopus oocytes have shown that removal of the N50 glycans increases the maximal peptide transport rate in the inward and outward directions. This effect could be largely reversed by replacement of N50 glycans with structurally dissimilar biotin derivatives. In addition, N-glycans were detected to stabilize PEPT1 against proteolytic cleavage.
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Affiliation(s)
- Tamara Stelzl
- Nutritional Physiology, Technische Universität München, Freising, Germany
| | | | - Jürgen Stolz
- Nutritional Physiology, Technische Universität München, Freising, Germany
| | - Hannelore Daniel
- Nutritional Physiology, Technische Universität München, Freising, Germany
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63
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Several hPepT1-transported drugs are substrates of the Escherichia coli proton-coupled oligopeptide transporter YdgR. Res Microbiol 2017; 168:443-449. [DOI: 10.1016/j.resmic.2017.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 01/24/2017] [Accepted: 01/26/2017] [Indexed: 11/23/2022]
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64
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Droce A, Sørensen JL, Sondergaard TE, Rasmussen JJ, Lysøe E, Giese H. PTR2 peptide transporters in Fusarium graminearum influence secondary metabolite production and sexual development. Fungal Biol 2017; 121:515-527. [PMID: 28390508 DOI: 10.1016/j.funbio.2017.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/14/2017] [Accepted: 02/14/2017] [Indexed: 10/20/2022]
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65
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Huo X, Wang C, Yu Z, Peng Y, Wang S, Feng S, Zhang S, Tian X, Sun C, Liu K, Deng S, Ma X. Human transporters, PEPT1/2, facilitate melatonin transportation into mitochondria of cancer cells: An implication of the therapeutic potential. J Pineal Res 2017; 62:e12390. [PMID: 28099762 DOI: 10.1111/jpi.12390] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 01/12/2017] [Indexed: 12/21/2022]
Abstract
Melatonin is present in virtually all organisms from bacteria to mammals, and it exhibits a broad spectrum of biological functions, including synchronization of circadian rhythms and oncostatic activity. Several functions of melatonin are mediated by its membrane receptors, but others are receptor-independent. For the latter, melatonin is required to penetrate membrane and enters intracellular compartments. However, the mechanism by which melatonin enters cells remains debatable. In this study, it was identified that melatonin and its sulfation metabolites were the substrates of oligopeptide transporter (PEPT) 1/2 and organic anion transporter (OAT) 3, respectively. The docking analysis showed that the binding of melatonin to PEPT1/2 was attributed to their low binding energy and suitable binding conformation in which melatonin was embedded in the active site of PEPT1/2 and fitted well with the cavity in three-dimensional space. PEPT1/2 transporters play a pivotal role in melatonin uptake in cells. Melatonin's membrane transportation via PEPT1/2 renders its oncostatic effect in malignant cells. For the first time, PEPT1/2 were identified to localize in the mitochondrial membrane of human cancer cell lines of PC3 and U118. PEPT1/2 facilitated the transportation of melatonin into mitochondria. Melatonin accumulation in mitochondria induced apoptosis of PC3 and U118 cells. Thus, PEPT1/2 can potentially be used as a cancer cell-targeted melatonin delivery system to improve the therapeutic effects of melatonin in cancer treatment.
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Affiliation(s)
- Xiaokui Huo
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Chao Wang
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Zhenlong Yu
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Yulin Peng
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Shumei Wang
- Key Laboratory of Digital Quality Evaluation of Chinese Materia Medica of State Administration of TCM, Guangdong Pharmaceutical University, Guangdong, China
| | - Shengnan Feng
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Shouji Zhang
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Xiangge Tian
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Chengpeng Sun
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Kexin Liu
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Sa Deng
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
| | - Xiaochi Ma
- Key Laboratory of Pharmacokinetic and Drug Transport of Liaoning, College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian, China
- Key Laboratory of Digital Quality Evaluation of Chinese Materia Medica of State Administration of TCM, Guangdong Pharmaceutical University, Guangdong, China
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66
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Pallitsch K, Schweifer A, Roller A, Hammerschmidt F. Towards the biodegradation pathway of fosfomycin. Org Biomol Chem 2017; 15:3276-3285. [PMID: 28352915 DOI: 10.1039/c7ob00546f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Three functionalised propylphosphonic acids were synthesised to study C-P bond cleavage in R. huakuii PMY1. (R)-1-Hydroxy-2-oxopropylphosphonic acid [(R)-5] was prepared by chiral resolution of (±)-dimethyl 1-hydroxy-2-methylallyllphosphonate [(±)-12], followed by ozonolysis and deprotection. The N-(l-alanyl)-substituted (1R,2R)-2-amino-1-hydroxypropylphosphonic acid 10, a potential precursor for 2-oxopropylphosphonic acid (5) in cells, was obtained by coupling the aminophosphonic acid with benzotriazole-activated Z-l-alanine and hydrogenolytic deprotection. (1R*,2R*)-1,2-Dihydroxy-3,3,3-trifluoropropylphosphonic acid, a potential inhibitor of C-P bond cleavage after conversion into its 2-oxo derivative in the cell, was accessed from trifluoroacetaldehyde hydrate via hydroxypropanenitrile 21, which was silylated and reduced to the aldehyde (±)-23. Diastereoselective addition of diethyl trimethylsilyl phosphite furnished diastereomeric α-siloxyphosphonates. The less polar one was converted to the desired racemic phosphonic acid (±)-(1R*,2R*)-9 as its ammonium salt.
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Affiliation(s)
- K Pallitsch
- University of Vienna, Institute of Organic Chemistry, Währingerstrasse 38, 1090, Vienna, Austria.
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67
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Quistgaard EM, Martinez Molledo M, Löw C. Structure determination of a major facilitator peptide transporter: Inward facing PepTSt from Streptococcus thermophilus crystallized in space group P3121. PLoS One 2017; 12:e0173126. [PMID: 28264013 PMCID: PMC5338821 DOI: 10.1371/journal.pone.0173126] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/15/2017] [Indexed: 12/03/2022] Open
Abstract
Major facilitator superfamily (MFS) peptide transporters (typically referred to as PepT, POT or PTR transporters) mediate the uptake of di- and tripeptides, and so play an important dietary role in many organisms. In recent years, a better understanding of the molecular basis for this process has emerged, which is in large part due to a steep increase in structural information. Yet, the conformational transitions underlying the transport mechanism are still not fully understood, and additional data is therefore needed. Here we report in detail the detergent screening, crystallization, experimental MIRAS phasing, and refinement of the peptide transporter PepTSt from Streptococcus thermophilus. The space group is P3121, and the protein is crystallized in a monomeric inward facing form. The binding site is likely to be somewhat occluded, as the lobe encompassing transmembrane helices 10 and 11 is markedly bent towards the central pore of the protein, but the extent of this potential occlusion could not be determined due to disorder at the apex of the lobe. Based on structural comparisons with the seven previously determined P212121 and C2221 structures of inward facing PepTSt, the structural flexibility as well as the conformational changes mediating transition between the inward open and inward facing occluded states are discussed. In conclusion, this report improves our understanding of the structure and conformational cycle of PepTSt, and can furthermore serve as a case study, which may aid in supporting future structure determinations of additional MFS transporters or other integral membrane proteins.
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Affiliation(s)
- Esben M. Quistgaard
- Centre for Structural Systems Biology (CSSB), DESY and European Molecular Biology Laboratory Hamburg, Hamburg, Germany
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Maria Martinez Molledo
- Centre for Structural Systems Biology (CSSB), DESY and European Molecular Biology Laboratory Hamburg, Hamburg, Germany
| | - Christian Löw
- Centre for Structural Systems Biology (CSSB), DESY and European Molecular Biology Laboratory Hamburg, Hamburg, Germany
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
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68
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Immadisetty K, Hettige J, Moradi M. What Can and Cannot Be Learned from Molecular Dynamics Simulations of Bacterial Proton-Coupled Oligopeptide Transporter GkPOT? J Phys Chem B 2016; 121:3644-3656. [PMID: 27959539 DOI: 10.1021/acs.jpcb.6b09733] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We have performed an extensive set of all-atom molecular dynamics (MD) simulations of a bacterial proton-coupled oligopeptide transporter (POT) in an explicit membrane environment. We have characterized both the local and global conformational dynamics of the transporter upon the proton and/or substrate binding, within a statistical framework. Our results reveal a clearly distinct behavior for local conformational dynamics in the absence and presence of the proton at the putative proton binding residue E310. Particularly, we find that the substrate binding conformation is drastically different in the two conditions, where the substrate binds to the protein in a lateral/vertical manner, in the presence/absence of the proton. We do not observe any statistically significant distinctive behavior in terms of the global conformational changes in different simulation conditions, within the time scales of our simulations. Our extensive simulations and analyses call into question the implicit assumption of many MD studies that local conformational changes observed in short simulations could provide clues to the global conformational changes that occur on much longer time scales. The linear regression analysis of quantities associated with the global conformational fluctuations, however, provides an indication of a mechanism involving the concerted motion of the transmembrane helices, consistent with the rocker-switch mechanism.
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Affiliation(s)
- Kalyan Immadisetty
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Jeevapani Hettige
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
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69
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Sánchez-Kopper A, Becker M, Pfizenmaier J, Kessler C, Karau A, Takors R. Tracking dipeptides at work-uptake and intracellular fate in CHO culture. AMB Express 2016; 6:48. [PMID: 27447702 PMCID: PMC4958091 DOI: 10.1186/s13568-016-0221-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 07/15/2016] [Indexed: 01/08/2023] Open
Abstract
Market demands for monoclonal antibodies (mAbs) are steadily increasing worldwide. As a result, production processes using Chinese hamster ovary cells (CHO) are in the focus of ongoing intensification studies for maximizing cell-specific and volumetric productivities. This includes the optimization of animal-derived component free (ADCF) cultivation media as part of good cell culture practice. Dipeptides are known to improve CHO culture performance. However, little or even conflicting assumptions exist about their putative import and functionality inside the cells. A set of well-known performance boosters and new dipeptide prospects was evaluated. The present study revealed that dipeptides are indeed imported in the cells, where they are decomposed to the amino acids building blocks. Subsequently, they are metabolized or, unexpectedly, secreted to the medium. Monoclonal antibody production boosting additives like l-alanine-l-glutamine (AQ) or glycyl-l-glutamine (GQ) can be assigned to fast or slow dipeptide uptake, respectively, thus pinpointing to the need to study dipeptide kinetics and to adjust their feeding individually for optimizing mAb production.
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70
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Newstead S. Recent advances in understanding proton coupled peptide transport via the POT family. Curr Opin Struct Biol 2016; 45:17-24. [PMID: 27865112 DOI: 10.1016/j.sbi.2016.10.018] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 10/22/2016] [Accepted: 10/26/2016] [Indexed: 10/20/2022]
Abstract
The POT family of membrane transporters use the inwardly directed proton electrochemical gradient to drive the uptake of essential nutrients into the cell. Originally discovered in bacteria, members of the family have been found in all kingdoms of life except the archaea. A remarkable feature of the family is their diverse substrate promiscuity. Whereas in mammals and bacteria they are predominantly di- and tri-peptide transporters, in plants the family has diverged to recognize nitrate, plant defence compounds and hormones. This promiscuity has led to the development of peptide-based pro-drugs that use PepT1 and PepT2, the mammalian homologues, to improve oral drug delivery. Recent crystal structures from bacterial and plant members of the family have revealed conserved features of the ligand-binding site and provided insights into post-translational regulation. Here I review the current understanding of transport, ligand promiscuity and regulation within the POT family.
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Affiliation(s)
- Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
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71
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Di- and tripeptide transport in vertebrates: the contribution of teleost fish models. J Comp Physiol B 2016; 187:395-462. [PMID: 27803975 DOI: 10.1007/s00360-016-1044-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/12/2016] [Accepted: 10/20/2016] [Indexed: 02/06/2023]
Abstract
Solute Carrier 15 (SLC15) family, alias H+-coupled oligopeptide cotransporter family, is a group of membrane transporters known for their role in the cellular uptake of di- and tripeptides (di/tripeptides) and peptide-like molecules. Of its members, SLC15A1 (PEPT1) chiefly mediates intestinal absorption of luminal di/tripeptides from dietary protein digestion, while SLC15A2 (PEPT2) mainly allows renal tubular reabsorption of di/tripeptides from ultrafiltration, SLC15A3 (PHT2) and SLC15A4 (PHT1) possibly interact with di/tripeptides and histidine in certain immune cells, and SLC15A5 has unknown function. Our understanding of this family in vertebrates has steadily increased, also due to the surge of genomic-to-functional information from 'non-conventional' animal models, livestock, poultry, and aquaculture fish species. Here, we review the literature on the SLC15 transporters in teleost fish with emphasis on SLC15A1 (PEPT1), one of the solute carriers better studied amongst teleost fish because of its relevance in animal nutrition. We report on the operativity of the transporter, the molecular diversity, and multiplicity of structural-functional solutions of the teleost fish orthologs with respect to higher vertebrates, its relevance at the intersection of the alimentary and osmoregulative functions of the gut, its response under various physiological states and dietary solicitations, and its possible involvement in examples of total body plasticity, such as growth and compensatory growth. By a comparative approach, we also review the few studies in teleost fish on SLC15A2 (PEPT2), SLC15A4 (PHT1), and SLC15A3 (PHT2). By representing the contribution of teleost fish to the knowledge of the physiology of di/tripeptide transport and transporters, we aim to fill the gap between higher and lower vertebrates.
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72
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Wang LY, Ravi VM, Leblanc G, Padrós E, Cladera J, Perálvarez-Marín A. Helical unwinding and side-chain unlocking unravel the outward open conformation of the melibiose transporter. Sci Rep 2016; 6:33776. [PMID: 27658476 PMCID: PMC5034317 DOI: 10.1038/srep33776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 08/30/2016] [Indexed: 11/09/2022] Open
Abstract
Molecular dynamics simulations have been used to study the alternate access mechanism of the melibiose transporter from Escherichia coli. Starting from the outward-facing partially occluded form, 2 out of 12 simulations produced an outward full open form and one partially open, whereas the rest yielded fully or partially occluded forms. The shape of the outward-open form resembles other outward-open conformations of secondary transporters. During the transporter opening, conformational changes in some loops are followed by changes in the periplasm region of transmembrane helix 7. Helical curvature relaxation and unlocking of hydrophobic and ionic locks promote the outward opening of the transporter making accessible the substrate binding site. In particular, FRET studies on mutants of conserved aromatic residues of extracellular loop 4 showed lack of substrate binding, emphasizing the importance of this loop for making crucial interactions that control the opening of the periplasmic side. This study indicates that the alternate access mechanism for the melibiose transporter fits better into a flexible gating mechanism rather than the archetypical helical rigid-body rocker-switch mechanism.
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Affiliation(s)
- Li-Ying Wang
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, and Centre d'Estudis en Biofísica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Vidhya M Ravi
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, and Centre d'Estudis en Biofísica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Gérard Leblanc
- Direction des Sciences du Vivant, Direction des programmes et valorization, CEA Fontenay-aux-Roses, 92265 Fontenay-aux-Roses CEDEX France
| | - Esteve Padrós
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, and Centre d'Estudis en Biofísica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Josep Cladera
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, and Centre d'Estudis en Biofísica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Alex Perálvarez-Marín
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, and Centre d'Estudis en Biofísica, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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73
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Identification of hepta-histidine as a candidate drug for Huntington's disease by in silico-in vitro- in vivo-integrated screens of chemical libraries. Sci Rep 2016; 6:33861. [PMID: 27653664 PMCID: PMC5032119 DOI: 10.1038/srep33861] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 09/02/2016] [Indexed: 12/13/2022] Open
Abstract
We identified drug seeds for treating Huntington’s disease (HD) by combining in vitro single molecule fluorescence spectroscopy, in silico molecular docking simulations, and in vivo fly and mouse HD models to screen for inhibitors of abnormal interactions between mutant Htt and physiological Ku70, an essential DNA damage repair protein in neurons whose function is known to be impaired by mutant Htt. From 19,468 and 3,010,321 chemicals in actual and virtual libraries, fifty-six chemicals were selected from combined in vitro-in silico screens; six of these were further confirmed to have an in vivo effect on lifespan in a fly HD model, and two chemicals exerted an in vivo effect on the lifespan, body weight and motor function in a mouse HD model. Two oligopeptides, hepta-histidine (7H) and Angiotensin III, rescued the morphological abnormalities of primary neurons differentiated from iPS cells of human HD patients. For these selected drug seeds, we proposed a possible common structure. Unexpectedly, the selected chemicals enhanced rather than inhibited Htt aggregation, as indicated by dynamic light scattering analysis. Taken together, these integrated screens revealed a new pathway for the molecular targeted therapy of HD.
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74
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Garai P, Chandra K, Chakravortty D. Bacterial peptide transporters: Messengers of nutrition to virulence. Virulence 2016; 8:297-309. [PMID: 27589415 DOI: 10.1080/21505594.2016.1221025] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Bacteria possess numerous peptide transporters for importing peptides as nutrients. However, these peptide transporters are now consistently reported to play a role in the virulence of various bacterial pathogens. Their ability to transport peptides has implications in antibacterial therapy as well. Therefore, it would be instrumental to have complete knowledge about the role of peptide transporters in mediating this cross connection between metabolism and pathogenesis. Studies on various peptide transporters in bacterial pathogens have improved our understanding of this field. In this review, we have given an overview of the functioning of bacterial peptide transporters and their contribution in virulence of major bacterial pathogens.
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Affiliation(s)
- Preeti Garai
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | - Kasturi Chandra
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | - Dipshikha Chakravortty
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
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75
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Bortolotti M, Ventura G, Jegatheesan P, Choisy C, Cynober L, De Bandt JP. Impact of qualitative and quantitative variations in nitrogen supply on catch-up growth in food-deprived-refed young rats. Clin Nutr 2016; 35:669-78. [DOI: 10.1016/j.clnu.2015.04.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 03/09/2015] [Accepted: 04/22/2015] [Indexed: 02/07/2023]
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76
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Samsudin F, Parker JL, Sansom MSP, Newstead S, Fowler PW. Accurate Prediction of Ligand Affinities for a Proton-Dependent Oligopeptide Transporter. Cell Chem Biol 2016; 23:299-309. [PMID: 27028887 PMCID: PMC4760754 DOI: 10.1016/j.chembiol.2015.11.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/22/2015] [Accepted: 11/04/2015] [Indexed: 12/04/2022]
Abstract
Membrane transporters are critical modulators of drug pharmacokinetics, efficacy, and safety. One example is the proton-dependent oligopeptide transporter PepT1, also known as SLC15A1, which is responsible for the uptake of the β-lactam antibiotics and various peptide-based prodrugs. In this study, we modeled the binding of various peptides to a bacterial homolog, PepTSt, and evaluated a range of computational methods for predicting the free energy of binding. Our results show that a hybrid approach (endpoint methods to classify peptides into good and poor binders and a theoretically exact method for refinement) is able to accurately predict affinities, which we validated using proteoliposome transport assays. Applying the method to a homology model of PepT1 suggests that the approach requires a high-quality structure to be accurate. Our study provides a blueprint for extending these computational methodologies to other pharmaceutically important transporter families. A hierarchical computational approach determines ligand affinities to transporters Lysine-containing dipeptides proposed to bind vertically like a tripeptide Experimental structures are vital for the accurate prediction of affinities A model of prodrug interactions to human PepT1 is suggested
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Affiliation(s)
- Firdaus Samsudin
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Joanne L Parker
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
| | - Philip W Fowler
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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77
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Stelzl T, Baranov T, Geillinger KE, Kottra G, Daniel H. Effect of N-glycosylation on the transport activity of the peptide transporter PEPT1. Am J Physiol Gastrointest Liver Physiol 2016; 310:G128-41. [PMID: 26585416 DOI: 10.1152/ajpgi.00350.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 11/10/2015] [Indexed: 01/31/2023]
Abstract
The intestinal peptide transporter PEPT1 provides bulk quantities of amino acids to epithelial cells. PEPT1 is a high-capacity and low-affinity solute carrier of the SLC15 family found in apical membranes of enterocytes in small intestine and distal colon. Surprisingly, murine PEPT1 (mPEPT1) has an apparent molecular mass of ∼95 kDa in the small intestine but ∼105 kDa in the large intestine. Here we describe studies on mPEPT1 protein glycosylation and how glycans affect transport function. Putative N-glycosylation sites of mPEPT1 were altered by site-directed mutagenesis followed by expression in Xenopus laevis oocytes. Replacement of six asparagine residues (N) at positions N50, N406, N439, N510, N515, and N532 by glutamine (Q) resulted in a decrease of the mPEPT1 mass by around 35 kDa. Electrophysiology revealed all glycosylation-deficient transporters to be functional with comparable expression levels in oocyte membranes. Strikingly, the mutant protein with N50Q exhibited a twofold decreased affinity for Gly-Sar but a 2.5-fold rise in the maximal inward currents compared with the wild-type protein. Elevated maximal transport currents were also recorded for cefadroxil and tri-l-alanine. Tracer flux studies performed with [(14)C]-Gly-Sar confirmed the reduction in substrate affinity and showed twofold increased maximal transport rates for the N50Q transporter. Elimination of individual N-glycosylation sites did not alter membrane expression in oocytes or overall transport characteristics except for the mutant protein N50Q. Because transporter surface density was not altered in N50Q, removal of the glycan at this location appears to accelerate the substrate turnover rate.
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Affiliation(s)
- Tamara Stelzl
- Chair of Nutritional Physiology, Technische Universität München, Freising, Germany; ZIEL, Institute for Food and Health, Freising, Germany
| | - Tatjana Baranov
- Chair of Nutritional Physiology, Technische Universität München, Freising, Germany; ZIEL, Institute for Food and Health, Freising, Germany
| | - Kerstin E Geillinger
- Chair of Nutritional Physiology, Technische Universität München, Freising, Germany; ZIEL, Institute for Food and Health, Freising, Germany
| | - Gabor Kottra
- Chair of Nutritional Physiology, Technische Universität München, Freising, Germany; ZIEL, Institute for Food and Health, Freising, Germany
| | - Hannelore Daniel
- Chair of Nutritional Physiology, Technische Universität München, Freising, Germany; ZIEL, Institute for Food and Health, Freising, Germany
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78
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Understanding transport by the major facilitator superfamily (MFS): structures pave the way. Nat Rev Mol Cell Biol 2016; 17:123-32. [PMID: 26758938 DOI: 10.1038/nrm.2015.25] [Citation(s) in RCA: 277] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Members of the major facilitator superfamily (MFS) of transport proteins are essential for the movement of a wide range of substrates across biomembranes. As this transport requires a series of conformational changes, structures of MFS transporters captured in different conformational states are needed to decipher the transport mechanism. Recently, a large number of MFS transporter structures have been determined, which has provided us with an unprecedented opportunity to understand general aspects of the transport mechanism. We propose an updated model for the conformational cycle of MFS transporters, the 'clamp-and-switch model', and discuss the role of so-called 'gating residues' and the substrate in modulating these conformational changes.
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79
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Abstract
The ancient and ubiquitous major facilitator superfamily (MFS) represents the largest secondary transporter family and plays a crucial role in a multitude of physiological processes. MFS proteins transport a broad spectrum of ions and solutes across membranes via facilitated diffusion, symport, or antiport. In recent years, remarkable advances in understanding the structural biology of the MFS transporters have been made. This article reviews the history, classification, and general features of the MFS proteins; summarizes recent structural progress with a focus on the sugar porter family transporters exemplified by GLUT1; and discusses the molecular mechanisms of substrate binding, alternating access, and cotransport coupling.
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Affiliation(s)
- Nieng Yan
- State Key Laboratory of Bio-membrane and Membrane Biotechnology, Center for Structural Biology, School of Medicine, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China;
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80
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Jørgensen ME, Olsen CE, Geiger D, Mirza O, Halkier BA, Nour-Eldin HH. A Functional EXXEK Motif is Essential for Proton Coupling and Active Glucosinolate Transport by NPF2.11. PLANT & CELL PHYSIOLOGY 2015; 56:2340-50. [PMID: 26443378 PMCID: PMC4675897 DOI: 10.1093/pcp/pcv145] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 09/24/2015] [Indexed: 05/02/2023]
Abstract
The proton-dependent oligopeptide transporter (POT/PTR) family shares a highly conserved E1X1X2E2RFXYY (E1X1X2E2R) motif across all kingdoms of life. This motif is suggested to have a role in proton coupling and active transport in bacterial homologs. For the plant POT/PTR family, also known as the NRT1/PTR family (NPF), little is known about the role of the E1X1X2E2R motif. Moreover, nothing is known about the role of the X1 and X2 residues within the E1X1X2E2R motif. We used NPF2.11-a proton-coupled glucosinolate (GLS) symporter from Arabidopsis thaliana-to investigate the role of the E1X1X2E2K motif variant in a plant NPF transporter. Using liquid chromatography-mass spectrometry (LC-MS)-based uptake assays and two-electrode voltage clamp (TEVC) electrophysiology, we demonstrate an essential role for the E1X1X2E2K motif for accumulation of substrate by NPF2.11. Our data suggest that the highly conserved E1, E2 and K residues are involved in translocation of protons, as has been proposed for the E1X1X2E2R motif in bacteria. Furthermore, we show that the two residues X1 and X2 in the E1X1X2E2[K/R] motif are conserved as uncharged amino acids in POT/PTRs from bacteria to mammals and that introducing a positive or negative charge in either position hampers the ability to overaccumulate substrate relative to the assay medium. We hypothesize that introducing a charge at X1 and X2 interferes with the function of the conserved glutamate and lysine residues of the E1X1X2E2K motif and affects the mechanism behind proton coupling.
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Affiliation(s)
- Morten Egevang Jørgensen
- DynaMo Center, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Carl Erik Olsen
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Dietmar Geiger
- Julius-von-Sachs-Institute, Molecular Plant Physiology and Biophysics, University of Würzburg, D-97082 Würzburg, Germany
| | - Osman Mirza
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Barbara Ann Halkier
- DynaMo Center, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Hussam Hassan Nour-Eldin
- DynaMo Center, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark
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81
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Beale JH, Parker JL, Samsudin F, Barrett AL, Senan A, Bird LE, Scott D, Owens RJ, Sansom MSP, Tucker SJ, Meredith D, Fowler PW, Newstead S. Crystal Structures of the Extracellular Domain from PepT1 and PepT2 Provide Novel Insights into Mammalian Peptide Transport. Structure 2015; 23:1889-1899. [PMID: 26320580 PMCID: PMC4597091 DOI: 10.1016/j.str.2015.07.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/22/2015] [Accepted: 07/28/2015] [Indexed: 12/11/2022]
Abstract
Mammals obtain nitrogen via the uptake of di- and tri-peptides in the gastrointestinal tract through the action of PepT1 and PepT2, which are members of the POT family of proton-coupled oligopeptide transporters. PepT1 and PepT2 also play an important role in drug transport in the human body. Recent crystal structures of bacterial homologs revealed a conserved peptide-binding site and mechanism of transport. However, a key structural difference exists between bacterial and mammalian homologs with only the latter containing a large extracellular domain, the function of which is currently unknown. Here, we present the crystal structure of the extracellular domain from both PepT1 and PepT2 that reveal two immunoglobulin-like folds connected in tandem, providing structural insight into mammalian peptide transport. Functional and biophysical studies demonstrate that these domains interact with the intestinal protease trypsin, suggesting a role in clustering proteolytic activity to the site of peptide transport in eukaryotic cells. Crystal structure of the extracellular domains of PepT1 and PepT2 Modular architecture for a mammalian MFS transporter Extracellular domains contain immunoglobulin-like fold and interact with trypsin
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Affiliation(s)
- John H Beale
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Joanne L Parker
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Firdaus Samsudin
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Anne L Barrett
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Anish Senan
- Department of Biological Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Louise E Bird
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK; OPPF-UK, Research Complex at Harwell, Harwell Oxford, Didcot, Oxfordshire OX11 0FA, UK
| | - David Scott
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0FA, UK; ISIS Spallation Neutron and Muon Source, Rutherford Appleton Laboratory, Oxfordshire OX11 0FA, UK; School of Biosciences, School of Biosciences, Sutton Bonington Campus, Leicestershire LE12 5RD, UK
| | - Raymond J Owens
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK; OPPF-UK, Research Complex at Harwell, Harwell Oxford, Didcot, Oxfordshire OX11 0FA, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; OXION Initiative in Ion Channels and Membrane Transport, University of Oxford OX1 3PU, UK
| | - Stephen J Tucker
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK; OXION Initiative in Ion Channels and Membrane Transport, University of Oxford OX1 3PU, UK
| | - David Meredith
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Philip W Fowler
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; OXION Initiative in Ion Channels and Membrane Transport, University of Oxford OX1 3PU, UK.
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82
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Boggavarapu R, Jeckelmann JM, Harder D, Ucurum Z, Fotiadis D. Role of electrostatic interactions for ligand recognition and specificity of peptide transporters. BMC Biol 2015; 13:58. [PMID: 26246134 PMCID: PMC4527243 DOI: 10.1186/s12915-015-0167-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 07/15/2015] [Indexed: 11/10/2022] Open
Abstract
Background Peptide transporters are membrane proteins that mediate the cellular uptake of di- and tripeptides, and of peptidomimetic drugs such as β-lactam antibiotics, antiviral drugs and antineoplastic agents. In spite of their high physiological and pharmaceutical importance, the molecular recognition by these transporters of the amino acid side chains of short peptides and thus the mechanisms for substrate binding and specificity are far from being understood. Results The X-ray crystal structure of the peptide transporter YePEPT from the bacterium Yersinia enterocolitica together with functional studies have unveiled the molecular bases for recognition, binding and specificity of dipeptides with a charged amino acid residue at the N-terminal position. In wild-type YePEPT, the significant specificity for the dipeptides Asp-Ala and Glu-Ala is defined by electrostatic interaction between the in the structure identified positively charged Lys314 and the negatively charged amino acid side chain of these dipeptides. Mutagenesis of Lys314 into the negatively charged residue Glu allowed tuning of the substrate specificity of YePEPT for the positively charged dipeptide Lys-Ala. Importantly, molecular insights acquired from the prokaryotic peptide transporter YePEPT combined with mutagenesis and functional uptake studies with human PEPT1 expressed in Xenopus oocytes also allowed tuning of human PEPT1’s substrate specificity, thus improving our understanding of substrate recognition and specificity of this physiologically and pharmaceutically important peptide transporter. Conclusion This study provides the molecular bases for recognition, binding and specificity of peptide transporters for dipeptides with a charged amino acid residue at the N-terminal position. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0167-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rajendra Boggavarapu
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland
| | - Jean-Marc Jeckelmann
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland
| | - Daniel Harder
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland
| | - Zöhre Ucurum
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland
| | - Dimitrios Fotiadis
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland.
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83
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Droce A, Holm KB, Olsson S, Frandsen RJN, Sondergaard TE, Sørensen JL, Giese H. Expression profiling and functional analyses of BghPTR2, a peptide transporter from Blumeria graminis f. sp. hordei. Fungal Biol 2015; 119:551-9. [PMID: 26058531 DOI: 10.1016/j.funbio.2015.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 02/04/2023]
Affiliation(s)
- Aida Droce
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg Ø, Denmark.
| | | | - Stefan Olsson
- Section for Genetics and Microbiology, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Copenhagen, Denmark
| | - Rasmus J N Frandsen
- Section for Eukaryotic Biotechnology, Department of Systems Biology, Technical University of Denmark, Søltofts Plads, Build 223, 2800 Kgs. Lyngby, Denmark
| | - Teis Esben Sondergaard
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg Ø, Denmark
| | - Jens Laurids Sørensen
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg Ø, Denmark
| | - Henriette Giese
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg Ø, Denmark
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84
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Freeman HJ. Clinical relevance of intestinal peptide uptake. World J Gastrointest Pharmacol Ther 2015; 6:22-27. [PMID: 25949847 PMCID: PMC4419090 DOI: 10.4292/wjgpt.v6.i2.22] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 11/22/2014] [Accepted: 04/02/2015] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine available information on an independent peptide transporter 1 (PepT1) and its potential relevance to treatment, this evaluation was completed.
METHODS: Fully published English language literature articles sourced through PubMed related to protein digestion and absorption, specifically human peptide and amino acid transport, were accessed and reviewed. Papers from 1970 to the present, with particular emphasis on the past decade, were examined. In addition, abstracted information translated to English in PubMed was also included. Finally, studies and reviews relevant to nutrient or drug uptake, particularly in human intestine were included for evaluation. This work represents a summary of all of these studies with particular reference to peptide transporter mediated assimilation of nutrients and pharmacologically active medications.
RESULTS: Assimilation of dietary protein in humans involves gastric and pancreatic enzyme hydrolysis to luminal oligopeptides and free amino acids. During the ensuing intestinal phase, these hydrolytic products are transported into the epithelial cell and, eventually, the portal vein. A critical component of this process is the uptake of intact di-peptides and tri-peptides by an independent PepT1. A number of “peptide-mimetic” pharmaceutical agents may also be transported through this carrier, important for uptake of different antibiotics, antiviral agents and angiotensin-converting enzyme inhibitors. In addition, specific peptide products of intestinal bacteria may also be transported by PepT1, with initiation and persistence of an immune response including increased cytokine production and associated intestinal inflammatory changes. Interestingly, these inflammatory changes may also be attenuated with orally-administered anti-inflammatory tripeptides administered as site-specific nanoparticles and taken up by this PepT1 transport protein.
CONCLUSION: Further evaluation of the role of this transporter in treatment of intestinal disorders, including inflammatory bowel disease is needed.
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85
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Parker JL, Mindell JA, Newstead S. Thermodynamic evidence for a dual transport mechanism in a POT peptide transporter. eLife 2014; 3. [PMID: 25457052 PMCID: PMC4271188 DOI: 10.7554/elife.04273] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 12/01/2014] [Indexed: 01/30/2023] Open
Abstract
Peptide transport plays an important role in cellular homeostasis as a key route for nitrogen acquisition in mammalian cells. PepT1 and PepT2, the mammalian proton coupled peptide transporters (POTs), function to assimilate and retain diet-derived peptides and play important roles in drug pharmacokinetics. A key characteristic of the POT family is the mechanism of peptide selectivity, with members able to recognise and transport >8000 different peptides. In this study, we present thermodynamic evidence that in the bacterial POT family transporter PepTSt, from Streptococcus thermophilus, at least two alternative transport mechanisms operate to move peptides into the cell. Whilst tri-peptides are transported with a proton:peptide stoichiometry of 3:1, di-peptides are co-transported with either 4 or 5 protons. This is the first thermodynamic study of proton:peptide stoichiometry in the POT family and reveals that secondary active transporters can evolve different coupling mechanisms to accommodate and transport chemically and physically diverse ligands across the membrane.
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Affiliation(s)
- Joanne L Parker
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Joseph A Mindell
- Membrane Transport Biophysics Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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86
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Belmondo S, Fiorilli V, Pérez-Tienda J, Ferrol N, Marmeisse R, Lanfranco L. A dipeptide transporter from the arbuscular mycorrhizal fungus Rhizophagus irregularis is upregulated in the intraradical phase. FRONTIERS IN PLANT SCIENCE 2014; 5:436. [PMID: 25232358 PMCID: PMC4153046 DOI: 10.3389/fpls.2014.00436] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/15/2014] [Indexed: 05/09/2023]
Abstract
Arbuscular mycorrhizal fungi (AMF), which form an ancient and widespread mutualistic symbiosis with plants, are a crucial but still enigmatic component of the plant micro biome. Nutrient exchange has probably been at the heart of the success of this plant-fungus interaction since the earliest days of plants on land. To characterize genes from the fungal partner involved in nutrient exchange, and presumably important for the functioning of the AM symbiosis, genome-wide transcriptomic data obtained from the AMF Rhizophagus irregularis were exploited. A gene sequence, showing amino acid sequence and transmembrane domains profile similar to members of the PTR2 family of fungal oligopeptide transporters, was identified and called RiPTR2. The functional properties of RiPTR2 were investigated by means of heterologous expression in Saccharomyces cerevisiae mutants defective in either one or both of its di/tripeptide transporter genes PTR2 and DAL5. These assays showed that RiPTR2 can transport dipeptides such as Ala-Leu, Ala-Tyr or Tyr-Ala. From the gene expression analyses it seems that RiPTR2 responds to different environmental clues when the fungus grows inside the root and in the extraradical phase.
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Affiliation(s)
- Simone Belmondo
- Department of Life Sciences and Systems Biology, University of TorinoTorino, Italy
| | - Valentina Fiorilli
- Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle RicercheTorino, Italy
| | - Jacob Pérez-Tienda
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Consejo Superior de Investigaciones CientificasGranada, Spain
| | - Nuria Ferrol
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Consejo Superior de Investigaciones CientificasGranada, Spain
| | - Roland Marmeisse
- Department of Life Sciences and Systems Biology, University of TorinoTorino, Italy
- Ecologie Microbienne, UMR CNRS 5557 - USC INRA 1364, Université Lyon 1, Université de LyonVilleurbanne, France
| | - Luisa Lanfranco
- Department of Life Sciences and Systems Biology, University of TorinoTorino, Italy
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