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Wright NJ, Zhang F, Suo Y, Kong L, Yin Y, Fedor JG, Sharma K, Borgnia MJ, Im W, Lee SY. Antiviral drug recognition and elevator-type transport motions of CNT3. Nat Chem Biol 2024; 20:1144-1153. [PMID: 38418906 DOI: 10.1038/s41589-024-01559-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 01/22/2024] [Indexed: 03/02/2024]
Abstract
Nucleoside analogs have broad clinical utility as antiviral drugs. Key to their systemic distribution and cellular entry are human nucleoside transporters. Here, we establish that the human concentrative nucleoside transporter 3 (CNT3) interacts with antiviral drugs used in the treatment of coronavirus infections. We report high-resolution single-particle cryo-electron microscopy structures of bovine CNT3 complexed with antiviral nucleosides N4-hydroxycytidine, PSI-6206, GS-441524 and ribavirin, all in inward-facing states. Notably, we found that the orally bioavailable antiviral molnupiravir arrests CNT3 in four distinct conformations, allowing us to capture cryo-electron microscopy structures of drug-loaded outward-facing and drug-loaded intermediate states. Our studies uncover the conformational trajectory of CNT3 during membrane transport of a nucleoside analog antiviral drug, yield new insights into the role of interactions between the transport and the scaffold domains in elevator-like domain movements during drug translocation, and provide insights into the design of nucleoside analog antiviral prodrugs with improved oral bioavailability.
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Affiliation(s)
- Nicholas J Wright
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Feng Zhang
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Yang Suo
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Lingyang Kong
- Departments of Biological Sciences, Chemistry, and Bioengineering, Lehigh University, Bethlehem, PA, USA
| | - Ying Yin
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Justin G Fedor
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Kedar Sharma
- Department of Health and Human Services, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, Durham, NC, USA
| | - Mario J Borgnia
- Department of Health and Human Services, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, Durham, NC, USA
| | - Wonpil Im
- Departments of Biological Sciences, Chemistry, and Bioengineering, Lehigh University, Bethlehem, PA, USA
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
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2
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Ou G, Tian Z, Su M, Yu M, Gong J, Chen Y. Identification of gemcitabine resistance-related AHNAK2 gene associated with prognosis and immune infiltration in pancreatic cancer. Heliyon 2024; 10:e33687. [PMID: 39040243 PMCID: PMC11261888 DOI: 10.1016/j.heliyon.2024.e33687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/25/2024] [Accepted: 06/25/2024] [Indexed: 07/24/2024] Open
Abstract
Purpose Gemcitabine is a basic chemotherapy drug for pancreatic cancer (PC), but resistance is common and causes tumor recurrence and metastasis. Therefore, it is significant to explore gemcitabine resistance-related molecules for individualized treatment and prognosis assessment of PC. Methods In this study, transcriptome sequencing and TCGA database analysis were performed, and a differentiated gene AHNAK2 was screened. MEXPRESS database, tissue microarray analysis, and CIBERSORT and TIMER databases were used to correlate AHNAK2 expression with clinicopathological features and prognosis and immune infiltration of PC. Enrichment analysis was used to investigate the significant biological processes associated with AHNAK2. Results AHNAK2 was highly expressed in gemcitabine-resistant cells. High expression of AHNAK2 increased the risk of poor overall survival (OS) and progression-free survival (PFS) in PC. Clinicopathologic analysis revealed that AHNAK2 correlated with KRAS, TP53 mutations, histologic type, short OS, N stage, and elevated CA199 levels in PC. Knockdown of AHNAK2 inhibited the ability of cell proliferation and colony formation and enhanced the toxic effect of gemcitabine in PC. Meanwhile, the knockdown of AHNAK2 expression enhanced cell-ECM adhesion, inhibited cell-cell adhesion, and downregulated the KRAS/p53 signaling pathway in PC. Furthermore, AHNAK2 was correlated with immune infiltration, especially B cells and macrophages. Conclusions Our study unveils for the first time the pivotal role of AHNAK2 in PC, particularly its association with gemcitabine resistance, clinical prognosis, and immune infiltration. AHNAK2 not only drives the proliferation and drug resistance of PC cells by potentially activating the KRAS/p53 pathway but also significantly impacts cell-cell and cell- ECM adhesion. Additionally, AHNAK2 plays a crucial role in modulating the tumor immune microenvironment. These insights underscore AHNAK2's unique potential as a novel therapeutic target for overcoming gemcitabine resistance, offering new perspectives for PC treatment strategies.
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Affiliation(s)
- Guangsheng Ou
- Department of Gastrointestinal Surgery, the Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510600, PR China
| | - Zhenfeng Tian
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, PR China
- Department of Gastroenterology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, PR China
| | - Mingxin Su
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, PR China
- Department of Gastroenterology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, PR China
| | - Miao Yu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, PR China
- Department of Gastroenterology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, PR China
| | - Jin Gong
- Department of General Surgery, the First Affiliated Hospital of Jinan University, Guangzhou, 510632, PR China
| | - Yinting Chen
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, PR China
- Department of Gastroenterology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, PR China
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3
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Iosifidou N, Anagnostopoulou E, Botou M, Kalfa E, Tatsaki E, Frillingos S. Elucidation of the Gemcitabine Transporters of Escherichia coli K-12 and Gamma-Proteobacteria Linked to Gemcitabine-Related Chemoresistance. Int J Mol Sci 2024; 25:7012. [PMID: 39000123 PMCID: PMC11241209 DOI: 10.3390/ijms25137012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 06/22/2024] [Accepted: 06/24/2024] [Indexed: 07/16/2024] Open
Abstract
Gemcitabine (2',2'-difluoro-2'-deoxycytidine), a widely used anticancer drug, is considered a gold standard in treating aggressive pancreatic cancers. Gamma-proteobacteria that colonize the pancreatic tumors contribute to chemoresistance against gemcitabine by metabolizing the drug to a less active and deaminated form. The gemcitabine transporters of these bacteria are unknown to date. Furthermore, there is no complete knowledge of the gemcitabine transporters in Escherichia coli or any other related proteobacteria. In this study, we investigate the complement of gemcitabine transporters in E. coli K-12 and two common chemoresistance-related bacteria (Klebsiella pneumoniae and Citrobacter freundii). We found that E. coli K-12 has two high-affinity gemcitabine transporters with distinct specificity properties, namely, NupC and NupG, whereas the gemcitabine transporters of C. freundii and K. pneumoniae include the NupC and NupG orthologs, functionally indistinguishable from their counterparts, and, in K. pneumoniae, one additional NupC variant, designated KpNupC2. All these bacterial transporters have a higher affinity for gemcitabine than their human counterparts. The highest affinity (KM 2.5-3.0 μΜ) is exhibited by NupGs of the bacteria-specific nucleoside-H+ symporter (NHS) family followed by NupCs (KM 10-13 μΜ) of the concentrative nucleoside transporter (CNT) family, 15-100 times higher than the affinities reported for the human gemcitabine transporter hENT1/SLC29A1, which is primarily associated with gemcitabine uptake in the pancreatic adenocarcinoma cells. Our results offer a basis for further insight into the role of specific bacteria in drug availability within tumors and for understanding the structure-function differences of bacterial and human drug transporters.
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Affiliation(s)
- Nikoleta Iosifidou
- Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (N.I.); (E.A.); (M.B.); (E.K.); (E.T.)
| | - Eleni Anagnostopoulou
- Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (N.I.); (E.A.); (M.B.); (E.K.); (E.T.)
| | - Maria Botou
- Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (N.I.); (E.A.); (M.B.); (E.K.); (E.T.)
| | - Eirini Kalfa
- Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (N.I.); (E.A.); (M.B.); (E.K.); (E.T.)
| | - Ekaterini Tatsaki
- Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (N.I.); (E.A.); (M.B.); (E.K.); (E.T.)
| | - Stathis Frillingos
- Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (N.I.); (E.A.); (M.B.); (E.K.); (E.T.)
- University Research Center of Ioannina (URCI), Institute of Biosciences, 45110 Ioannina, Greece
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Robert Li Y, Traore K, Zhu H. Novel molecular mechanisms of doxorubicin cardiotoxicity: latest leading-edge advances and clinical implications. Mol Cell Biochem 2024; 479:1121-1132. [PMID: 37310587 DOI: 10.1007/s11010-023-04783-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/04/2023] [Indexed: 06/14/2023]
Abstract
Doxorubicin (Dox) is among the most widely used cancer chemotherapeutic drugs. The clinical use of Dox is, however, limited due to its cardiotoxicity. Studies over the past several decades have suggested various mechanisms of Dox-induced cardiotoxicity (DIC). Among them are oxidative stress, topoisomerase inhibition, and mitochondrial damage. Several novel molecular targets and signaling pathways underlying DIC have emerged over the past few years. The most notable advances include discovery of ferroptosis as a major form of cell death in Dox cytotoxicity, and elucidation of the involvement of cardiogenetics and regulatory RNAs as well as multiple other targets in DIC. In this review, we discuss these advances, focusing on latest cutting-edge research discoveries from mechanistic studies reported in influential journals rather than surveying all research studies available in the literature.
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Affiliation(s)
- Y Robert Li
- Department of Pharmacology, Campbell University Jerry Wallace School of Osteopathic Medicine, Buies Creek, NC, 27560, USA.
| | - Kassim Traore
- Department of Biochemistry, Duquesne University College of Osteopathic Medicine, Pittsburgh, PA, 15282, USA
| | - Hong Zhu
- Department of Physiology and Pathophysiology, Campbell University Jerry Wallace School of Osteopathic Medicine, Buies Creek, NC, 27560, USA
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5
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Duan H, Hu K, Zheng D, Cheng Y, Zhang Z, Wang Y, Liang L, Hu J, Luo T. Recognition and release of uridine and hCNT3: From multivariate interactions to molecular design. Int J Biol Macromol 2022; 223:1562-1577. [PMID: 36402394 DOI: 10.1016/j.ijbiomac.2022.11.145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/09/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022]
Abstract
As a vital target for the development of novel anti-cancer drugs, human concentrative nucleoside transporter 3 (hCNT3) has been widely concerned. Nevertheless, the lack of a comprehensive understanding of molecular interactions and motion mechanism has greatly hindered the development of novel inhibitors against hCNT3. In this paper, molecular recognition of hCNT3 with uridine was investigated with molecular docking, conventional molecular dynamics (CMD) simulations and adaptive steered molecular dynamics (ASMD) simulations; and then, the uridine derivatives with possibly highly inhibitory activity were designed. The result of CMD showed that more water-mediated H-bonds and lower binding free energy both explained higher recognition ability and transported efficiency of hCNT3. While during the ASMD simulation, nucleoside transport process involved the significant side-chain flip of residues F321 and Q142, a typical substrate-induced conformational change. By considering electronegativity, atomic radius, functional group and key H-bonds factors, 25 novel uridine derivatives were constructed. Subsequently, the receptor-ligand binding free energy was predicted by solvated interaction energy (SIE) method to determine the inhibitor c8 with the best potential performance. This work not only revealed molecular recognition and release mechanism of uridine with hCNT3, but also designed a series of uridine derivatives to obtain lead compounds with potential high activity.
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Affiliation(s)
- Huaichuan Duan
- Department of Head, Neck and Mammary Gland Oncology, Cancer Center, Clinical Research Center for Breast, West China Hospital, Sichuan University, Chengdu, China
| | - Kaixuan Hu
- School of Pharmaceutical Sciences, Jishou University, Jishou, China
| | - Dan Zheng
- Department of Head, Neck and Mammary Gland Oncology, Cancer Center, Clinical Research Center for Breast, West China Hospital, Sichuan University, Chengdu, China
| | - Yan Cheng
- Department of Head, Neck and Mammary Gland Oncology, Cancer Center, Clinical Research Center for Breast, West China Hospital, Sichuan University, Chengdu, China
| | - Zelan Zhang
- Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, School of Pharmacy, Chengdu University, Chengdu, China
| | - Yueteng Wang
- Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, School of Pharmacy, Chengdu University, Chengdu, China
| | - Li Liang
- Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, School of Pharmacy, Chengdu University, Chengdu, China
| | - Jianping Hu
- Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, School of Pharmacy, Chengdu University, Chengdu, China
| | - Ting Luo
- Department of Head, Neck and Mammary Gland Oncology, Cancer Center, Clinical Research Center for Breast, West China Hospital, Sichuan University, Chengdu, China.
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6
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Wright NJ, Lee SY. Recent advances on the inhibition of human solute carriers: Therapeutic implications and mechanistic insights. Curr Opin Struct Biol 2022; 74:102378. [PMID: 35487145 DOI: 10.1016/j.sbi.2022.102378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/02/2022] [Accepted: 03/18/2022] [Indexed: 11/03/2022]
Abstract
Solute carriers (SLCs) are membrane transport proteins tasked with mediating passage of hydrophilic molecules across lipid bilayers. Despite the extensive roles played in all aspects of human biology, SLCs remain vastly under-explored as therapeutic targets. In this brief review, we first discuss a few successful cases of drugs that exert their mechanisms of action through inhibition of human SLCs, and introduce select examples of human SLCs that have untapped therapeutic potential. We then highlight two recent structural studies which uncovered detailed structural mechanisms of inhibition exhibited against two different human major facilitator superfamily (MFS) transporters of clinical relevance.
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Affiliation(s)
- Nicholas J Wright
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA. https://twitter.com/@nick_rite
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA.
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7
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Sauer DB, Wang B, Sudar JC, Song J, Marden J, Rice WJ, Wang DN. The ups and downs of elevator-type di-/tricarboxylate membrane transporters. FEBS J 2022; 289:1515-1523. [PMID: 34403567 PMCID: PMC9832446 DOI: 10.1111/febs.16158] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/27/2021] [Accepted: 08/16/2021] [Indexed: 01/13/2023]
Abstract
The divalent anion sodium symporter (DASS) family contains both sodium-driven anion cotransporters and anion/anion exchangers. The family belongs to a broader ion transporter superfamily (ITS), which comprises 24 families of transporters, including those of AbgT antibiotic efflux transporters. The human proteins in the DASS family play major physiological roles and are drug targets. We recently determined multiple structures of the human sodium-dependent citrate transporter (NaCT) and the succinate/dicarboxylate transporter from Lactobacillus acidophilus (LaINDY). Structures of both proteins show high degrees of structural similarity to the previously determined VcINDY fold. Conservation between these DASS protein structures and those from the AbgT family indicates that the VcINDY fold represents the overall protein structure for the entire ITS. The new structures of NaCT and LaINDY are captured in the inward- or outward-facing conformations, respectively. The domain arrangements in these structures agree with a rigid body elevator-type transport mechanism for substrate translocation across the membrane. Two separate NaCT structures in complex with a substrate or an inhibitor allowed us to explain the inhibition mechanism and propose a detailed classification scheme for grouping disease-causing mutations in the human protein. Structural understanding of multiple kinetic states of DASS proteins is a first step toward the detailed characterization of their entire transport cycle.
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Affiliation(s)
- David B. Sauer
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Bing Wang
- Cryo-Electron Microscopy Core, New York University School of Medicine, New York, NY 10016, USA
| | - Joseph C. Sudar
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Jinmei Song
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Jennifer Marden
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - William J. Rice
- Cryo-Electron Microscopy Core, New York University School of Medicine, New York, NY 10016, USA
| | - Da-Neng Wang
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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8
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Duan H, Zhou Y, Shi X, Luo Q, Gao J, Liang L, Liu W, Peng L, Deng D, Hu J. Allosteric and transport modulation of human concentrative nucleoside transporter 3 at the atomic scale. Phys Chem Chem Phys 2021; 23:25401-25413. [PMID: 34751688 DOI: 10.1039/d1cp03756k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Nucleosides are important precursors of nucleotide synthesis in cells, and nucleoside transporters play an important role in many physiological processes by mediating transmembrane transport and absorption. During nucleoside transport, such proteins undergo a significant conformational transition between the outward- and inward-facing states, which leads to alternating access of the substrate-binding site to either side of the membrane. In this work, a variety of molecular simulation methods have been applied to comparatively investigate the motion modes of human concentrative nucleoside transporter 3 (hCNT3) in three states, as well as global and local cavity conformational changes; and finally, a possible elevator-like transport mechanism consistent with experimental data was proposed. The results of the Gaussian network model (GNM) and anisotropic network model (ANM) show that hCNT3 as a whole tends to contract inwards and shift towards a membrane inside, exhibiting an allosteric process that is more energetically favorable than the rigid conversion. To reveal the complete allosteric process of hCNT3 in detail, a series of intermediate conformations were obtained by an adaptive anisotropic network model (aANM). One of the simulated intermediate states is similar to that of a crystal structure, which indicates that the allosteric process is reliable; the state with lower energy is slightly inclined to the inward-facing structure rather than the expected intermediate crystal structure. The final HOLE analysis showed that except for the outward-facing state, the transport channels were gradually enlarged, which was conductive to the directional transport of nucleosides. Our work provides a theoretical basis for the multistep elevator-like transportation mechanism of nucleosides, which helps to further understand the dynamic recognition between nucleoside substrates and hCNT3 as well as the design of nucleoside anticancer drugs.
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Affiliation(s)
- Huaichuan Duan
- School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China.
| | - Yanxia Zhou
- Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, Department of Obstetrics, West China Second Hospital, Sichuan University, Chengdu, China.
| | - Xiaodong Shi
- School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China.
| | - Qing Luo
- School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China.
| | - Jiaxing Gao
- School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China.
| | - Li Liang
- School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China.
| | - Wei Liu
- School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China.
| | - Lianxin Peng
- School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China.
| | - Dong Deng
- Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, Department of Obstetrics, West China Second Hospital, Sichuan University, Chengdu, China.
| | - Jianping Hu
- School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China.
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Abstract
Nucleosides play central roles in all facets of life, from metabolism to cellular signaling. Because of their physiochemical properties, nucleosides are lipid bilayer impermeable and thus rely on dedicated transport systems to cross biological membranes. In humans, two unrelated protein families mediate nucleoside membrane transport: the concentrative and equilibrative nucleoside transporter families. The objective of this review is to provide a broad outlook on the current status of nucleoside transport research. We will discuss the role played by nucleoside transporters in human health and disease, with emphasis placed on recent structural advancements that have revealed detailed molecular principles of these important cellular transport systems and exploitable pharmacological features.
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Affiliation(s)
- Nicholas J. Wright
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, North Carolina, 27710, USA
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, North Carolina, 27710, USA
- Correspondence and requests for materials should be addressed to: S.-Y. Lee., , tel: 919-684-1005, fax: 919-684-8885
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10
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Cabrero C, Martín-Pintado N, Mazzini S, Gargallo R, Eritja R, Aviñó A, González C. Structural Effects of Incorporation of 2'-Deoxy-2'2'-Difluorodeoxycytidine (Gemcitabine) in A- and B-Form Duplexes. Chemistry 2021; 27:7351-7355. [PMID: 33772916 DOI: 10.1002/chem.202100503] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Indexed: 11/06/2022]
Abstract
We report the structural effect of 2'-deoxy-2',2'-difluorocytidine (dFdC) insertions in the DNA strand of a DNA : RNA hybrid duplex and in a self-complementary DNA : DNA duplex. In both cases, the modification slightly destabilizes the duplex and provokes minor local distortions that are more pronounced in the case of the DNA : RNA hybrid. Analysis of the solution structures determined by NMR methods show that dFdC is an adaptable derivative that adopts North type sugar conformation when inserted in pure DNA, or a South sugar conformation in the context of DNA : RNA hybrids. In this latter context, South sugar pucker favors the formation of a 2'F⋅⋅H8 attractive interaction with a neighboring purine, which compensates the destabilizing effect of base pair distortions. These interactions share some features with pseudohydrogen bonds described previously in other nucleic acids structures with fluorine modified sugars.
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Affiliation(s)
- Cristina Cabrero
- Instituto de Química Física Rocasolano, CSIC, Serrano, 119, 28006, Madrid, Spain
| | - Nerea Martín-Pintado
- Instituto de Química Física Rocasolano, CSIC, Serrano, 119, 28006, Madrid, Spain
| | - Stefania Mazzini
- Department of Food, Environmental and Nutritional Sciences (DEFENS), Università degli Studi di Milano, Via Celoria 2, 20133, Milano, Italy
| | - Raimundo Gargallo
- Dept. of Chemical Engineering and Analytical Chemistry, University of Barcelona, Marti i Franquès 1, 08028, Barcelona, Spain.,BIOESTRAN associated unit UB-CSIC, 08028, Barcelona, Spain
| | - Ramon Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC) CIBER-BBN, Jordi, Girona 18-26, 08034, Barcelona, Spain
| | - Anna Aviñó
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC) CIBER-BBN, Jordi, Girona 18-26, 08034, Barcelona, Spain
| | - Carlos González
- Instituto de Química Física Rocasolano, CSIC, Serrano, 119, 28006, Madrid, Spain.,BIOESTRAN associated unit UB-CSIC, 08028, Barcelona, Spain
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11
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Okawa F, Hama Y, Zhang S, Morishita H, Yamamoto H, Levine TP, Mizushima N. Evolution and insights into the structure and function of the DedA superfamily containing TMEM41B and VMP1. J Cell Sci 2021; 134:237813. [PMID: 33771928 DOI: 10.1242/jcs.255877] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/15/2021] [Indexed: 12/21/2022] Open
Abstract
TMEM41B and VMP1 are endoplasmic reticulum (ER)-localizing multi-spanning membrane proteins required for ER-related cellular processes such as autophagosome formation, lipid droplet homeostasis and lipoprotein secretion in eukaryotes. Both proteins have a VTT domain, which is similar to the DedA domain found in bacterial DedA family proteins. However, the molecular function and structure of the DedA and VTT domains (collectively referred to as DedA domains) and the evolutionary relationships among the DedA domain-containing proteins are largely unknown. Here, we conduct a remote homology search and identify a new clade consisting mainly of bacterial proteins of unknown function that are members of the Pfam family PF06695. Phylogenetic analysis reveals that the TMEM41, VMP1, DedA and PF06695 families form a superfamily with a common origin, which we term the DedA superfamily. Coevolution-based structural prediction suggests that the DedA domain contains two reentrant loops facing each other in the membrane. This topology is biochemically verified by the substituted cysteine accessibility method. The predicted structure is topologically similar to that of the substrate-binding region of Na+-coupled glutamate transporter solute carrier 1 (SLC1) proteins. A potential ion-coupled transport function of the DedA superfamily proteins is discussed. This article has an associated First Person interview with the joint first authors of the paper.
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Affiliation(s)
- Fumiya Okawa
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yutaro Hama
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Sidi Zhang
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hideaki Morishita
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hayashi Yamamoto
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tim P Levine
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
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12
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Grixti JM, Ayers D, Day PJR. An Analysis of Mechanisms for Cellular Uptake of miRNAs to Enhance Drug Delivery and Efficacy in Cancer Chemoresistance. Noncoding RNA 2021; 7:27. [PMID: 33923485 PMCID: PMC8167612 DOI: 10.3390/ncrna7020027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/11/2021] [Accepted: 04/13/2021] [Indexed: 12/15/2022] Open
Abstract
Up until recently, it was believed that pharmaceutical drugs and their metabolites enter into the cell to gain access to their targets via simple diffusion across the hydrophobic lipid cellular membrane, at a rate which is based on their lipophilicity. An increasing amount of evidence indicates that the phospholipid bilayer-mediated drug diffusion is in fact negligible, and that drugs pass through cell membranes via proteinaceous membrane transporters or carriers which are normally used for the transportation of nutrients and intermediate metabolites. Drugs can be targeted to specific cells and tissues which express the relevant transporters, leading to the design of safe and efficacious treatments. Furthermore, transporter expression levels can be manipulated, systematically and in a high-throughput manner, allowing for considerable progress in determining which transporters are used by specific drugs. The ever-expanding field of miRNA therapeutics is not without its challenges, with the most notable one being the safe and effective delivery of the miRNA mimic/antagonist safely to the target cell cytoplasm for attaining the desired clinical outcome, particularly in miRNA-based cancer therapeutics, due to the poor efficiency of neo-vascular systems revolting around the tumour site, brought about by tumour-induced angiogenesis. This acquisition of resistance to several types of anticancer drugs can be as a result of an upregulation of efflux transporters expression, which eject drugs from cells, hence lowering drug efficacy, resulting in multidrug resistance. In this article, the latest available data on human microRNAs has been reviewed, together with the most recently described mechanisms for miRNA uptake in cells, for future therapeutic enhancements against cancer chemoresistance.
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Affiliation(s)
- Justine M. Grixti
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Biosciences Building, University of Liverpool, Liverpool L69 7ZB, UK;
| | - Duncan Ayers
- Centre for Molecular Medicine and Biobanking, University of Malta, Msida MSD 2080, Malta
- Faculty of Biology, Medicine and Human Sciences, The University of Manchester, Manchester M1 7DN, UK;
| | - Philip J. R. Day
- Faculty of Biology, Medicine and Human Sciences, The University of Manchester, Manchester M1 7DN, UK;
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13
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Molecular basis for substrate recognition by the bacterial nucleoside transporter NupG. J Biol Chem 2021; 296:100479. [PMID: 33640454 PMCID: PMC8042404 DOI: 10.1016/j.jbc.2021.100479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/22/2021] [Accepted: 02/24/2021] [Indexed: 11/20/2022] Open
Abstract
Nucleoside homeostasis, which is mediated by transporters and channels, is essential for all life on Earth. In Escherichia coli, NupG mediates the transport of nucleosides and was deemed to be the prototype of the nucleoside proton symporter (NHS) family and the major facilitator superfamily. To date, the substrate recognition and transport mechanisms of NHS transporters are still elusive. Here, we report two crystal structures of NupG (WT and D323A NupG) resolved at 3.0 Å. Both structures reveal an identical inward-open conformation. Together with molecular docking and molecular dynamics simulations and in vitro uridine-binding assays, we found that the uridine binding site, which locates in the central cavity between N and C domains of NupG, is constituted by R136, T140, F143, Q225, N228, Q261, E264, Y318, and F322. Moreover, we found that D323 is very important for substrate binding via in vitro uridine-binding assays using D323 mutations, although it does not have a direct contact with uridine. Our structural and biochemical data therefore provide an important framework for the mechanistic understanding of nucleoside transporters of the NHS family.
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14
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Elevator-type mechanisms of membrane transport. Biochem Soc Trans 2021; 48:1227-1241. [PMID: 32369548 PMCID: PMC7329351 DOI: 10.1042/bst20200290] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/29/2020] [Accepted: 03/31/2020] [Indexed: 12/13/2022]
Abstract
Membrane transporters are integral membrane proteins that mediate the passage of solutes across lipid bilayers. These proteins undergo conformational transitions between outward- and inward-facing states, which lead to alternating access of the substrate-binding site to the aqueous environment on either side of the membrane. Dozens of different transporter families have evolved, providing a wide variety of structural solutions to achieve alternating access. A sub-set of structurally diverse transporters operate by mechanisms that are collectively named 'elevator-type'. These transporters have one common characteristic: they contain a distinct protein domain that slides across the membrane as a rigid body, and in doing so it 'drags" the transported substrate along. Analysis of the global conformational changes that take place in membrane transporters using elevator-type mechanisms reveals that elevator-type movements can be achieved in more than one way. Molecular dynamics simulations and experimental data help to understand how lipid bilayer properties may affect elevator movements and vice versa.
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15
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Dissecting the Conformational Dynamics of the Bile Acid Transporter Homologue ASBT NM. J Mol Biol 2021; 433:166764. [PMID: 33359100 DOI: 10.1016/j.jmb.2020.166764] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/11/2020] [Accepted: 12/11/2020] [Indexed: 11/21/2022]
Abstract
Apical sodium-dependent bile acid transporter (ASBT) catalyses uphill transport of bile acids using the electrochemical gradient of Na+ as the driving force. The crystal structures of two bacterial homologues ASBTNM and ASBTYf have previously been determined, with the former showing an inward-facing conformation, and the latter adopting an outward-facing conformation accomplished by the substitution of the critical Na+-binding residue glutamate-254 with an alanine residue. While the two crystal structures suggested an elevator-like movement to afford alternating access to the substrate binding site, the mechanistic role of Na+ and substrate in the conformational isomerization remains unclear. In this study, we utilized site-directed alkylation monitored by in-gel fluorescence (SDAF) to probe the solvent accessibility of the residues lining the substrate permeation pathway of ASBTNM under different Na+ and substrate conditions, and interpreted the conformational states inferred from the crystal structures. Unexpectedly, the crosslinking experiments demonstrated that ASBTNM is a monomer protein, unlike the other elevator-type transporters, usually forming a homodimer or a homotrimer. The conformational dynamics observed by the biochemical experiments were further validated using DEER measuring the distance between the spin-labelled pairs. Our results revealed that Na+ ions shift the conformational equilibrium of ASBTNM toward the inward-facing state thereby facilitating cytoplasmic uptake of substrate. The current findings provide a novel perspective on the conformational equilibrium of secondary active transporters.
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16
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Abstract
Drug transporters are integral membrane proteins that play a critical role in drug disposition by affecting absorption, distribution, and excretion. They translocate drugs, as well as endogenous molecules and toxins, across membranes using ATP hydrolysis, or ion/concentration gradients. In general, drug transporters are expressed ubiquitously, but they function in drug disposition by being concentrated in tissues such as the intestine, the kidneys, the liver, and the brain. Based on their primary sequence and their mechanism, transporters can be divided into the ATP-binding cassette (ABC), solute-linked carrier (SLC), and the solute carrier organic anion (SLCO) superfamilies. Many X-ray crystallography and cryo-electron microscopy (cryo-EM) structures have been solved in the ABC and SLC transporter superfamilies or of their bacterial homologs. The structures have provided valuable insight into the structural basis of transport. This chapter will provide particular focus on the promiscuous drug transporters because of their effect on drug disposition and the challenges associated with them.
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Affiliation(s)
- Arthur G Roberts
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, Athens, GA, USA.
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17
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Forciniti S, Dalla Pozza E, Greco MR, Amaral Carvalho TM, Rolando B, Ambrosini G, Carmona-Carmona CA, Pacchiana R, Di Molfetta D, Donadelli M, Arpicco S, Palmieri M, Reshkin SJ, Dando I, Cardone RA. Extracellular Matrix Composition Modulates the Responsiveness of Differentiated and Stem Pancreatic Cancer Cells to Lipophilic Derivate of Gemcitabine. Int J Mol Sci 2020; 22:ijms22010029. [PMID: 33375106 PMCID: PMC7792955 DOI: 10.3390/ijms22010029] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 12/15/2020] [Accepted: 12/18/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease. Gemcitabine (GEM) is used as the gold standard drug in PDAC treatment. However, due to its poor efficacy, it remains urgent to identify novel strategies to overcome resistance issues. In this context, an intense stroma reaction and the presence of cancer stem cells (CSCs) have been shown to influence PDAC aggressiveness, metastatic potential, and chemoresistance. METHODS We used three-dimensional (3D) organotypic cultures grown on an extracellular matrix composed of Matrigel or collagen I to test the effect of the new potential therapeutic prodrug 4-(N)-stearoyl-GEM, called C18GEM. We analyzed C18GEM cytotoxic activity, intracellular uptake, apoptosis, necrosis, and autophagy induction in both Panc1 cell line (P) and their derived CSCs. RESULTS PDAC CSCs show higher sensitivity to C18GEM treatment when cultured in both two-dimensional (2D) and 3D conditions, especially on collagen I, in comparison to GEM. The intracellular uptake mechanisms of C18GEM are mainly due to membrane nucleoside transporters' expression and fatty acid translocase CD36 in Panc1 P cells and to clathrin-mediated endocytosis and CD36 in Panc1 CSCs. Furthermore, C18GEM induces an increase in cell death compared to GEM in both cell lines grown on 2D and 3D cultures. Finally, C18GEM stimulated protective autophagy in Panc1 P and CSCs cultured on 3D conditions. CONCLUSION We propose C18GEM together with autophagy inhibitors as a valid alternative therapeutic approach in PDAC treatment.
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Affiliation(s)
- Stefania Forciniti
- Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, 37134 Verona, Italy; (S.F.); (E.D.P.); (G.A.); (C.A.C.-C.); (R.P.); (M.D.); (M.P.)
- Humanitas Clinical and Research Center, IRCCS, Department of Gastroenterology-Laboratory of Molecular Gastroenterology, 20089 Rozzano, Milan, Italy
| | - Elisa Dalla Pozza
- Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, 37134 Verona, Italy; (S.F.); (E.D.P.); (G.A.); (C.A.C.-C.); (R.P.); (M.D.); (M.P.)
| | - Maria Raffaella Greco
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70126 Bari, Italy; (M.R.G.); (T.M.A.C.); (D.D.M.); (S.J.R.); (R.A.C.)
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Tiago Miguel Amaral Carvalho
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70126 Bari, Italy; (M.R.G.); (T.M.A.C.); (D.D.M.); (S.J.R.); (R.A.C.)
| | - Barbara Rolando
- Department of Drug Science and Technology, University of Torino, 10124 Torino, Italy; (B.R.); (S.A.)
| | - Giulia Ambrosini
- Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, 37134 Verona, Italy; (S.F.); (E.D.P.); (G.A.); (C.A.C.-C.); (R.P.); (M.D.); (M.P.)
| | - Cristian Andres Carmona-Carmona
- Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, 37134 Verona, Italy; (S.F.); (E.D.P.); (G.A.); (C.A.C.-C.); (R.P.); (M.D.); (M.P.)
| | - Raffaella Pacchiana
- Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, 37134 Verona, Italy; (S.F.); (E.D.P.); (G.A.); (C.A.C.-C.); (R.P.); (M.D.); (M.P.)
| | - Daria Di Molfetta
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70126 Bari, Italy; (M.R.G.); (T.M.A.C.); (D.D.M.); (S.J.R.); (R.A.C.)
| | - Massimo Donadelli
- Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, 37134 Verona, Italy; (S.F.); (E.D.P.); (G.A.); (C.A.C.-C.); (R.P.); (M.D.); (M.P.)
| | - Silvia Arpicco
- Department of Drug Science and Technology, University of Torino, 10124 Torino, Italy; (B.R.); (S.A.)
| | - Marta Palmieri
- Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, 37134 Verona, Italy; (S.F.); (E.D.P.); (G.A.); (C.A.C.-C.); (R.P.); (M.D.); (M.P.)
| | - Stephan Joel Reshkin
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70126 Bari, Italy; (M.R.G.); (T.M.A.C.); (D.D.M.); (S.J.R.); (R.A.C.)
| | - Ilaria Dando
- Department of Neurosciences, Biomedicine and Movement Sciences, Biochemistry Section, University of Verona, 37134 Verona, Italy; (S.F.); (E.D.P.); (G.A.); (C.A.C.-C.); (R.P.); (M.D.); (M.P.)
- Correspondence:
| | - Rosa Angela Cardone
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70126 Bari, Italy; (M.R.G.); (T.M.A.C.); (D.D.M.); (S.J.R.); (R.A.C.)
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18
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Nicklisch SC, Hamdoun A. Disruption of small molecule transporter systems by Transporter-Interfering Chemicals (TICs). FEBS Lett 2020; 594:4158-4185. [PMID: 33222203 PMCID: PMC8112642 DOI: 10.1002/1873-3468.14005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 12/25/2022]
Abstract
Small molecule transporters (SMTs) in the ABC and SLC families are important players in disposition of diverse endo- and xenobiotics. Interactions of environmental chemicals with these transporters were first postulated in the 1990s, and since validated in numerous in vitro and in vivo scenarios. Recent results on the co-crystal structure of ABCB1 with the flame-retardant BDE-100 demonstrate that a diverse range of man-made and natural toxic molecules, hereafter termed transporter-interfering chemicals (TICs), can directly bind to SMTs and interfere with their function. TIC-binding modes mimic those of substrates, inhibitors, modulators, inducers, and possibly stimulants through direct and allosteric mechanisms. Similarly, the effects could directly or indirectly agonize, antagonize or perhaps even prime the SMT system to alter transport function. Importantly, TICs are distinguished from drugs and pharmaceuticals that interact with transporters in that exposure is unintended and inherently variant. Here, we review the molecular mechanisms of environmental chemical interaction with SMTs, the methodological considerations for their evaluation, and the future directions for TIC discovery.
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Affiliation(s)
- Sascha C.T. Nicklisch
- Department of Environmental Toxicology, University of California, Davis, Davis, CA 95616
| | - Amro Hamdoun
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0202
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19
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Webster P, Saito K, Cortez J, Ramirez C, Baum MM. Concentrative Nucleoside Transporter 3 Is Located on Microvilli of Vaginal Epithelial Cells. ACS OMEGA 2020; 5:20882-20889. [PMID: 32875223 PMCID: PMC7450627 DOI: 10.1021/acsomega.0c02329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/29/2020] [Indexed: 06/11/2023]
Abstract
Transporters are specialized integral membrane proteins, which mediate the passage of virtually all molecules through cell membranes. They are expressed in a broad range of human and animal tissues and play important roles in both normal and disease states. For these reasons, they are evaluated when developing and testing drugs. Two major families of drug transporters, the adenosine 5'-triphosphate-binding cassette and solute carrier transporters (SLC), have critical roles in the absorption, distribution, metabolism, and elimination of drugs. The SLC family contains known nucleoside transporters and therefore are important when nucleoside analogs are used as drugs to prevent or treat viral infections. In this study, we wanted to determine if it was possible to locate one member of the SLC family, the human concentrative nucleoside transporter 3 (CNT3) in human vaginal epithelial cells. The CNT3 protein has important roles in drug delivery, subsequent drug tissue distribution, and, hence, efficacy. Vaginal epithelial cells, taken from two human volunteers (one Caucasian and one African American), were labeled for light and electron microscopy, with a commercial antibody to a cytoplasmic domain of CNT3, the protein product of the SLC28A3 gene. Fluorescent secondary antibodies or protein A-gold were used to detect antibody binding. By electron microscopy, gold particle binding was quantified to determine labeling specificity. By light microscopy, positive labeling with anti-CNT3 antibodies was detected on human vaginal epithelial cells, but specificity to any intracellular structure was not easily determined, most likely a result of specimen preparation. Electron microscopy revealed that the CNT3 transporter protein was present predominantly on microvilli located on one side of some human vaginal epithelial cells. Quantification confirmed specific anti-CNT3 labeling over human vaginal epithelial cell microvilli. The CNT3 protein, present in the microvilli of human vaginal epithelial cells, may have a role in redistributing nucleoside homologues delivered to the vaginal tract. Transporter proteins such as CNT3 could shuttle nucleosides and their analogs through the vaginal epithelium to immune cells located in lower cell layers. Outer layers of cells, which are eventually shed from the epithelium, may remove accumulated nucleoside drug analogs from the vaginal tract.
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Affiliation(s)
- Paul Webster
- Oak
Crest Institute of Science, 132 W. Chestnut Avenue, Monrovia, California 91016, United States
| | - Kaori Saito
- Oak
Crest Institute of Science, 132 W. Chestnut Avenue, Monrovia, California 91016, United States
| | - John Cortez
- Oak
Crest Institute of Science, 132 W. Chestnut Avenue, Monrovia, California 91016, United States
| | - Christina Ramirez
- Los
Angeles (UCLA) Fielding School of Public Health, University of California, Los Angeles, 650 Charles E. Young Dr. South, 16-035 Center for
Health Sciences, Los Angeles, California 90095-1772, United States
| | - Marc M. Baum
- Oak
Crest Institute of Science, 132 W. Chestnut Avenue, Monrovia, California 91016, United States
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20
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Zhou Y, Liao L, Wang C, Li J, Chi P, Xiao Q, Liu Q, Guo L, Sun L, Deng D. Cryo-EM structure of the human concentrative nucleoside transporter CNT3. PLoS Biol 2020; 18:e3000790. [PMID: 32776918 PMCID: PMC7440666 DOI: 10.1371/journal.pbio.3000790] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 08/20/2020] [Accepted: 07/20/2020] [Indexed: 01/17/2023] Open
Abstract
Concentrative nucleoside transporters (CNTs), members of the solute carrier (SLC) 28 transporter family, facilitate the salvage of nucleosides and therapeutic nucleoside derivatives across the plasma membrane. Despite decades of investigation, the structures of human CNTs remain unknown. We determined the cryogenic electron microscopy (cryo-EM) structure of human CNT (hCNT) 3 at an overall resolution of 3.6 Å. As with its bacterial homologs, hCNT3 presents a trimeric architecture with additional N-terminal transmembrane helices to stabilize the conserved central domains. The conserved binding sites for the substrate and sodium ions unravel the selective nucleoside transport and distinct coupling mechanism. Structural comparison of hCNT3 with bacterial homologs indicates that hCNT3 is stabilized in an inward-facing conformation. This study provides the molecular determinants for the transport mechanism of hCNTs and potentially facilitates the design of nucleoside drugs.
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Affiliation(s)
- Yanxia Zhou
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, China
| | - Lianghuan Liao
- Hefei National Laboratory for Physical Sciences at Microscale, CAS Centre for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Chen Wang
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, China
| | - Jialu Li
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, China
| | - Pengliang Chi
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, China
| | - Qingjie Xiao
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, China
| | - Qingting Liu
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, China
| | - Li Guo
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, China
| | - Linfeng Sun
- Hefei National Laboratory for Physical Sciences at Microscale, CAS Centre for Excellence in Molecular Cell Science, School of Life Sciences, University of Science and Technology of China, Hefei, China
- * E-mail: (LS); (DD)
| | - Dong Deng
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, China
- * E-mail: (LS); (DD)
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21
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Ardhapure AV, Gayakhe V, Bhilare S, Kapdi AR, Bag SS, Sanghvi YS, Gunturu KC. Extended fluorescent uridine analogues: synthesis, photophysical properties and selective interaction with BSA protein. NEW J CHEM 2020. [DOI: 10.1039/d0nj02803g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The improvement in fluorescence properties of 2′-deoxyuridine was made possible by the introduction of (hetero)aromatic moieties at the C–5 position of uridine with alkenyl/phenyl/styryl linkers to create a library of useful fluorescent nucleosides.
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Affiliation(s)
| | - Vijay Gayakhe
- Department of Chemistry
- Institute of Chemical Technology
- Matunga
- Mumbai-400019
- India
| | - Shatrughn Bhilare
- Department of Chemistry
- Institute of Chemical Technology
- Matunga
- Mumbai-400019
- India
| | - Anant R. Kapdi
- Department of Chemistry
- Institute of Chemical Technology
- Matunga
- Mumbai-400019
- India
| | - Subhendu Sekhar Bag
- Bioorganic Chemistry Laboratory
- Department of Chemistry
- Indian Institute of Technology
- Guwahati 781039
- India
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22
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Salmaso V, Jacobson KA. Survey of ribose ring pucker of signaling nucleosides and nucleotides. NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS 2019; 39:322-341. [PMID: 31460850 PMCID: PMC7047539 DOI: 10.1080/15257770.2019.1658115] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 08/12/2019] [Accepted: 08/17/2019] [Indexed: 02/08/2023]
Abstract
The ribose of protein-bound nucleosides and nucleotides displays preferred conformations (usually either North or South), which can be exploited to design enhanced analogs having chemically fixed conformations. We introduce a computational protocol for assembling data from the protein database (PDB) on the ribose and ribose-like conformation of small molecule ligands when complexed with purinergic signaling proteins (including receptors, enzymes and transporters, and related intracellular pathways). Some targets prefer exclusively North (adenosine and P2Y1 receptors, CD73, adenosine kinase ATP/ADP-binding site, adenosine deaminase), others prefer South (P2Y12 receptor, E-NTPDase2) or East (adenosine kinase substrates), while others (P2XRs) allow various conformations.
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Affiliation(s)
- Veronica Salmaso
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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23
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Structures of human ENT1 in complex with adenosine reuptake inhibitors. Nat Struct Mol Biol 2019; 26:599-606. [PMID: 31235912 PMCID: PMC6705415 DOI: 10.1038/s41594-019-0245-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 05/08/2019] [Indexed: 02/06/2023]
Abstract
The human Equilibrative Nucleoside Transporter 1 (hENT1), a member of the SLC29 family, plays crucial roles in adenosine signaling, cellular uptake of nucleoside for DNA and RNA synthesis, and nucleoside-derived anticancer and antiviral drug transport in human. Because of its central role in adenosine signaling, it is the target of adenosine reuptake inhibitors (AdoRI), several of which are clinically used. Despite its importance in human physiology and pharmacology, the molecular basis of hENT1-mediated adenosine transport and its inhibition by AdoRIs are limited due to the absence of structural information on hENT1. Here we present crystal structures of hENT1 in complex with two chemically distinct AdoRIs: dilazep and S-(4-Nitrobenzyl)-6-thioinosine (NBMPR). Combined with mutagenesis study, our structural analyses elucidate two distinct inhibitory mechanisms exhibited on hENT1, while giving insight into adenosine recognition and transport. Our studies provide the platform for improved pharmacological intervention of adenosine and nucleoside analog drug transport by hENT1.
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24
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Kuk ACY, Hao A, Guan Z, Lee SY. Visualizing conformation transitions of the Lipid II flippase MurJ. Nat Commun 2019; 10:1736. [PMID: 30988294 PMCID: PMC6465408 DOI: 10.1038/s41467-019-09658-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 03/22/2019] [Indexed: 02/06/2023] Open
Abstract
The biosynthesis of many polysaccharides, including bacterial peptidoglycan and eukaryotic N-linked glycans, requires transport of lipid-linked oligosaccharide (LLO) precursors across the membrane by specialized flippases. MurJ is the flippase for the lipid-linked peptidoglycan precursor Lipid II, a key player in bacterial cell wall synthesis, and a target of recently discovered antibacterials. However, the flipping mechanism of LLOs including Lipid II remains poorly understood due to a dearth of structural information. Here we report crystal structures of MurJ captured in inward-closed, inward-open, inward-occluded and outward-facing conformations. Together with mutagenesis studies, we elucidate the conformational transitions in MurJ that mediate lipid flipping, identify the key ion for function, and provide a framework for the development of inhibitors. MurJ is the flippase for the lipid-linked peptidoglycan precursor Lipid II, a key player in bacterial cell wall synthesis, but the flipping mechanism remains poorly understood. Here authors report crystal structures of MurJ in different conformations which shed light on the MurJ transitions that mediate lipid flipping.
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Affiliation(s)
- Alvin C Y Kuk
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA
| | - Aili Hao
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA.
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25
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Bag SS, Gogoi H. Design of "Click" Fluorescent Labeled 2'-deoxyuridines via C5-[4-(2-Propynyl(methyl)amino)]phenyl Acetylene as a Universal Linker: Synthesis, Photophysical Properties, and Interaction with BSA. J Org Chem 2018; 83:7606-7621. [PMID: 29877080 DOI: 10.1021/acs.joc.7b03097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Microenvironment-sensitive fluorescent nucleosides present attractive advantages over single-emitting dyes for sensing inter-biomolecular interactions involving DNA. Herein, we report the rational design and synthesis of triazolyl push-pull fluorophore-labeled uridines via the intermediacy of C5-[4-(2-propynyl(methyl)amino)]phenyl acetylene as a universal linker. The synthesized nucleosides showed interesting solvatochromic characteristic and/or intramolecular charge transfer (ICT) features. A few of them also exhibited dual-emitting characteristics evidencing our designing concept. The HOMO-LUMO distribution showed that the emissive states of these nucleosides were characterized with more significant electron redistribution between the C5-[4-(2-propynyl(methyl)amino)]phenyl triazolyl donor moiety and the aromatic chromophores linked to it, leading to modulated emission property. The solvent polarity sensitivity of these nucleosides was also tested. The synthesized triazolyl benzonitrile (10C), naphthyl (10E), and pyrenyl (10G) nucleosides were found to exhibit interesting ICT and dual (LE/ICT) emission properties. The dual-emitting pyrenyl nucleoside maintained a good ratiometric response in the BSA protein microenvironment, enabling the switch-on ratiometric sensing of BSA as the only protein biomolecule. Thus, it is expected that the new fluorescent nucleoside analogues would be useful in designing DNA probes for nucleic acid analysis or studying DNA-protein interactions via a drastic change in fluorescence response due to a change in micropolarity.
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Affiliation(s)
- Subhendu Sekhar Bag
- Bioorganic Chemistry Laboratory, Department of Chemistry , Indian Institute of Technology Guwahati 781039 , India
| | - Hiranya Gogoi
- Bioorganic Chemistry Laboratory, Department of Chemistry , Indian Institute of Technology Guwahati 781039 , India
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26
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Jacobson KA, Tosh DK, Toti KS, Ciancetta A. Polypharmacology of conformationally locked methanocarba nucleosides. Drug Discov Today 2017; 22:1782-1791. [PMID: 28781163 PMCID: PMC5705437 DOI: 10.1016/j.drudis.2017.07.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 06/13/2017] [Accepted: 07/26/2017] [Indexed: 12/13/2022]
Abstract
A single molecular scaffold can be adapted to interact with diverse targets, either separately or simultaneously. Nucleosides and nucleotides in which ribose is substituted with bicyclo[3.1.0]hexane are an example of a versatile drug-like scaffold for increasing selectivity at their classical targets: kinases, polymerases, adenosine and P2 receptors. Also, by applying structure-based functional group manipulations, rigidified adenosine derivatives can be repurposed to satisfy pharmacophoric requirements of various GPCRs, ion channels, enzymes and transporters, initially detected as off-target activities. Recent examples include 5HT2B serotonin receptor antagonists and novel dopamine transporter allosteric modulators. This directable target diversity establishes rigid nucleosides as privileged scaffolds.
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Affiliation(s)
- Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bldg 8A, Rm B1A-19, Bethesda, MD 20892-0810, USA.
| | - Dilip K Tosh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bldg 8A, Rm B1A-19, Bethesda, MD 20892-0810, USA
| | - Kiran S Toti
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bldg 8A, Rm B1A-19, Bethesda, MD 20892-0810, USA
| | - Antonella Ciancetta
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bldg 8A, Rm B1A-19, Bethesda, MD 20892-0810, USA
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27
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Martínez-Casares RM, Pérez Méndez HI, Manjarrez Alvarez N, Solís Oba A, Hernández Vázquez L, López-Luna A. Comparison of the diastereoisomeric excess of uridine, inosine and adenosine cyanohydrins determined by HPLC-DAD and 1H NMR. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2017; 36:652-665. [PMID: 29185863 DOI: 10.1080/15257770.2017.1375516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The separation of the diastereoisomers of the nucleoside derivatives of uridine, inosine and adenosine was performed by HPLC using chiral and no chiral columns, it was observed with the no chiral columns the resolution was good enough to determine diastereoisomeric excess. These methods were compared with 1H NMR, and no significant differences were observed between the three techniques. Diastereoisomeric uridine (3a), inosine (3b) and adenosine (4c) cyanohydrins were resolved by 1H nuclear magnetic resonance (1H NMR), chiral normal phase-high-performance liquid chromatography-diode array detector (NP-HPLC-DAD) and reversed phase (RP-HPLC-DAD); these methods allowed the assesment of the percent diastereoisomeric excess (% de) of the nucleosidic cyanohydrins of 3a (4, 6 and 4), 3b (10, 8 and 6) and 4c (4, 4 and 4). To the best of our knowledge, there are no reports using analytical techniques for the separation of the epimers of 3a, 3b and 4c.
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Affiliation(s)
- Rubria Marlen Martínez-Casares
- a Doctorado en Ciencias Biológicas y de la Salud , Universidad Autónoma Metropolitana-Unidad Xochimilco , Coyoacán , CDMX , México
| | - Herminia Inés Pérez Méndez
- b Departamento de Sistemas Biológicos , Universidad Autónoma Metropolitana-Unidad Xochimilco , Coyoacán , CDMX , México
| | - Norberto Manjarrez Alvarez
- b Departamento de Sistemas Biológicos , Universidad Autónoma Metropolitana-Unidad Xochimilco , Coyoacán , CDMX , México
| | - Aida Solís Oba
- b Departamento de Sistemas Biológicos , Universidad Autónoma Metropolitana-Unidad Xochimilco , Coyoacán , CDMX , México
| | - Liliana Hernández Vázquez
- b Departamento de Sistemas Biológicos , Universidad Autónoma Metropolitana-Unidad Xochimilco , Coyoacán , CDMX , México
| | - Alberto López-Luna
- b Departamento de Sistemas Biológicos , Universidad Autónoma Metropolitana-Unidad Xochimilco , Coyoacán , CDMX , México
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28
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Rational Design of Nucleoside-Bile Acid Conjugates Incorporating a Triazole Moiety for Anticancer Evaluation and SAR Exploration. Molecules 2017; 22:molecules22101710. [PMID: 29023408 PMCID: PMC6151511 DOI: 10.3390/molecules22101710] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 11/17/2022] Open
Abstract
Herein we report a study on the synthesis and biological evaluation of a library of nucleoside-bile acid conjugates prepared by combining 2′-deoxyadenosine, 2′-deoxyguanosine, 2′-deoxyuridine as well as adenosine and guanosine derivatives with cheno-, urso-, nor-cheno-, nor-urso- and taurourso-desoxycholic acid derivatives by means of the click reaction. The new nucleoside-bile acid conjugates incorporating a triazole moiety were tested in vitro against leukemic K562 and HCT116 colon carcinoma, as well as on normal fibroblast cells. Six compounds displayed interesting anti-proliferative activity against the selected cancer lines and no cytotoxic effects against normal fibroblasts. A possible structure activity relationship was also investigated.
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29
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Ramírez-Guadiana FH, Meeske AJ, Rodrigues CDA, Barajas-Ornelas RDC, Kruse AC, Rudner DZ. A two-step transport pathway allows the mother cell to nurture the developing spore in Bacillus subtilis. PLoS Genet 2017; 13:e1007015. [PMID: 28945739 PMCID: PMC5629000 DOI: 10.1371/journal.pgen.1007015] [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: 08/14/2017] [Revised: 10/05/2017] [Accepted: 09/09/2017] [Indexed: 11/18/2022] Open
Abstract
One of the hallmarks of bacterial endospore formation is the accumulation of high concentrations of pyridine-2,6-dicarboxylic acid (dipicolinic acid or DPA) in the developing spore. This small molecule comprises 5–15% of the dry weight of dormant spores and plays a central role in resistance to both wet heat and desiccation. DPA is synthesized in the mother cell at a late stage in sporulation and must be translocated across two membranes (the inner and outer forespore membranes) that separate the mother cell and forespore. The enzymes that synthesize DPA and the proteins required to translocate it across the inner forespore membrane were identified over two decades ago but the factors that transport DPA across the outer forespore membrane have remained mysterious. Here, we report that SpoVV (formerly YlbJ) is the missing DPA transporter. SpoVV is produced in the mother cell during the morphological process of engulfment and specifically localizes in the outer forespore membrane. Sporulating cells lacking SpoVV produce spores with low levels of DPA and cells engineered to express SpoVV and the DPA synthase during vegetative growth accumulate high levels of DPA in the culture medium. SpoVV resembles concentrative nucleoside transporters and mutagenesis of residues predicted to form the substrate-binding pocket supports the idea that SpoVV has a similar structure and could therefore function similarly. These findings provide a simple two-step transport mechanism by which the mother cell nurtures the developing spore. DPA produced in the mother cell is first translocated into the intermembrane space by SpoVV and is then imported into the forespore by the SpoVA complex. This pathway is likely to be broadly conserved as DPA synthase, SpoVV, and SpoVA proteins can be found in virtually all endospore forming bacteria. All pathogenic and non-pathogenic bacteria that differentiate into dormant endospores including Clostridium difficile, Bacillus anthracis, and Bacillus subtilis, contain very high concentrations of the small molecule dipicolinic acid (DPA). This molecule displaces water in the spore core where it plays an integral role in spore resistance and dormancy. DPA and its contribution to spore dehydration were discovered in 1953 but the molecular basis for its accumulation in the spore has remained unclear. The developing endospore resides within a mother cell that assembles protective layers around the spore and nurtures it by providing mother-cell-produced molecules. DPA is produced in the mother cell at a late stage in development and then must be translocated across two membranes into the spore core. Here, we report the discovery of the missing DPA transporter, homologs of which are present in virtually all endospore-forming bacteria. Our data provide evidence for a simple two-step transport pathway in which the mother cell nurtures the developing spore by sequentially moving DPA across the two membranes that surround it.
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Affiliation(s)
| | - Alexander J. Meeske
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | | | | | - Andrew C. Kruse
- Department of Biochemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States of America
| | - David Z. Rudner
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
- * E-mail:
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30
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Latek D. Rosetta Broker for membrane protein structure prediction: concentrative nucleoside transporter 3 and corticotropin-releasing factor receptor 1 test cases. BMC STRUCTURAL BIOLOGY 2017; 17:8. [PMID: 28774292 PMCID: PMC5543540 DOI: 10.1186/s12900-017-0078-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 07/26/2017] [Indexed: 02/12/2023]
Abstract
Background Membrane proteins are difficult targets for structure prediction due to the limited structural data deposited in Protein Data Bank. Most computational methods for membrane protein structure prediction are based on the comparative modeling. There are only few de novo methods targeting that distinct protein family. In this work an example of such de novo method was used to structurally and functionally characterize two representatives of distinct membrane proteins families of solute carrier transporters and G protein-coupled receptors. The well-known Rosetta program and one of its protocols named Broker was used in two test cases. The first case was de novo structure prediction of three N-terminal transmembrane helices of the human concentrative nucleoside transporter 3 (hCNT3) homotrimer belonging to the solute carrier 28 family of transporters (SLC28). The second case concerned the large scale refinement of transmembrane helices of a homology model of the corticotropin-releasing factor receptor 1 (CRFR1) belonging to the G protein-coupled receptors family. Results The inward-facing model of the hCNT3 homotrimer was used to propose the functional impact of its single nucleotide polymorphisms. Additionally, the 100 ns molecular dynamics simulation of the unliganded hCNT3 model confirmed its validity and revealed mobility of the selected binding site and homotrimer interface residues. The large scale refinement of transmembrane helices of the CRFR1 homology model resulted in the significant improvement of its accuracy with respect to the crystal structure of CRFR1, especially in the binding site area. Consequently, the antagonist CP-376395 could be docked with Autodock VINA to the CRFR1 model without any steric clashes. Conclusions The presented work demonstrated that Rosetta Broker can be a versatile tool for solving various issues referring to protein biology. Two distinct examples of de novo membrane protein structure prediction presented here provided important insights into three major areas of protein biology. Namely, the dynamics of the inward-facing hCNT3 homotrimer system, the structural changes of the CRFR1 receptor upon the antagonist binding and finally, the role of single nucleotide polymorphisms in both, hCNT3 and CRFR1 proteins, were investigated. Electronic supplementary material The online version of this article (doi:10.1186/s12900-017-0078-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dorota Latek
- Faculty of Chemistry, University of Warsaw, Pasteur St. 1, 02-093, Warsaw, Poland.
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31
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Stecula A, Schlessinger A, Giacomini KM, Sali A. Human Concentrative Nucleoside Transporter 3 (hCNT3, SLC28A3) Forms a Cyclic Homotrimer. Biochemistry 2017; 56:3475-3483. [PMID: 28661652 DOI: 10.1021/acs.biochem.7b00339] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Many anticancer and antiviral drugs are purine or pyrimidine analogues, which use membrane transporters to cross cellular membranes. Concentrative nucleoside transporters (CNTs) mediate the salvage of nucleosides and the transport of therapeutic nucleoside analogues across plasma membranes by coupling the transport of ligands to the sodium gradient. Of the three members of the human CNT family, CNT3 has the broadest selectivity and the widest expression profile. However, the molecular mechanisms of the transporter, including how it interacts with and translocates structurally diverse nucleosides and nucleoside analogues, are unclear. Recently, the crystal structure of vcCNT showed that the prokaryotic homologue of CNT3 forms a homotrimer. In this study, we successfully expressed and purified the wild type human homologue, hCNT3, demonstrating the homotrimer by size exclusion profiles and glutaraldehyde cross-linking. Further, by creating a series of cysteine mutants at highly conserved positions guided by comparative structure models, we cross-linked hCNT3 protomers in a cell-based assay, thus showing the existence of hCNT3 homotrimers in human cells. The presence and absence of cross-links at specific locations along TM9 informs us of important structural differences between vcCNT and hCNT3. Comparative modeling of the trimerization domain and sequence coevolution analysis both indicate that oligomerization is critical to the stability and function of hCNT3. In particular, trimerization appears to shorten the translocation path for nucleosides across the plasma membrane and may allow modulation of the transport function via allostery.
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Affiliation(s)
- Adrian Stecula
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco , San Francisco, California 94158, United States
| | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
| | - Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco , San Francisco, California 94158, United States.,California Institute for Quantitative Biosciences, University of California, San Francisco , San Francisco, California 94158, United States.,Department of Pharmaceutical Chemistry, University of California, San Francisco , San Francisco, California 94158, United States.,Institute for Human Genetics, University of California, San Francisco , San Francisco, California 94158, United States
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco , San Francisco, California 94158, United States.,California Institute for Quantitative Biosciences, University of California, San Francisco , San Francisco, California 94158, United States.,Department of Pharmaceutical Chemistry, University of California, San Francisco , San Francisco, California 94158, United States
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32
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Rizzuto I, Ghazaly E, Peters GJ. Pharmacological factors affecting accumulation of gemcitabine's active metabolite, gemcitabine triphosphate. Pharmacogenomics 2017; 18:911-925. [PMID: 28594276 DOI: 10.2217/pgs-2017-0034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Gemcitabine is an anticancer agent acting against several solid tumors. It requires nucleoside transporters for cellular uptake and deoxycytidine kinase for activation into active gemcitabine-triphosphate, which is incorporated into the DNA and RNA. However, it can also be deaminated in the plasma. The intracellular level of gemcitabine-triphosphate is affected by scheduling or by combination with other chemotherapeutic regimens. Moreover, higher concentrations of gemcitabine-triphosphate may affect the toxicity, and possibly the clinical efficacy. As a consequence, different nucleoside analogs have been synthetized with the aim to increase the concentration of gemcitabine-triphosphate into cells. In this review, we summarize currently published evidence on pharmacological factors affecting the intracellular level of gemcitabine-triphosphate to guide future trials on the use of new nucleoside analogs.
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Affiliation(s)
| | | | - Godefridus J Peters
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
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33
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Structural insights into the elevator-like mechanism of the sodium/citrate symporter CitS. Sci Rep 2017; 7:2548. [PMID: 28566738 PMCID: PMC5451387 DOI: 10.1038/s41598-017-02794-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 04/19/2017] [Indexed: 11/09/2022] Open
Abstract
The sodium-dependent citrate transporter of Klebsiella pneumoniae (KpCitS) belongs to the 2-hydroxycarboxylate transporter (2-HCT) family and allows the cell to use citrate as sole carbon and energy source in anaerobic conditions. Here we present crystal structures of KpCitS in citrate-bound outward-facing, citrate-bound asymmetric, and citrate-free inward-facing state. The structures reveal that the KpCitS dimerization domain remains stationary throughout the transport cycle due to a hydrogen bond network as well as extensive hydrophobic interactions. In contrast, its transport domain undergoes a ~35° rigid-body rotation and a ~17 Å translocation perpendicular to the membrane to expose the substrate-binding site alternately to either side of the membrane. Furthermore, homology models of two other 2-HCT proteins based on the KpCitS structure offer structural insights into their differences in substrate specificity at a molecular level. On the basis of our results and previous biochemical data, we propose that the activity of the 2-HCT CitS involves an elevator-like movement in which the transport domain itself traverses the lipid bilayer, carrying the substrate into the cell in a sodium-dependent manner.
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34
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Arimany-Nardi C, Claudio-Montero A, Viel-Oliva A, Schmidtke P, Estarellas C, Barril X, Bidon-Chanal A, Pastor-Anglada M. Identification and Characterization of a Secondary Sodium-Binding Site and the Main Selectivity Determinants in the Human Concentrative Nucleoside Transporter 3. Mol Pharm 2017; 14:1980-1987. [DOI: 10.1021/acs.molpharmaceut.7b00085] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C. Arimany-Nardi
- Departament
de Bioquímica i Biomedicina Molecular, Facultat de Biologia and Institute of Biomedicine (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
- Oncology
Program, National Biomedical Research Institute on Liver and Gastrointestinal
Diseases (CIBER EHD), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - A. Claudio-Montero
- Departament
de Bioquímica i Biomedicina Molecular, Facultat de Biologia and Institute of Biomedicine (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
- Oncology
Program, National Biomedical Research Institute on Liver and Gastrointestinal
Diseases (CIBER EHD), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - A. Viel-Oliva
- Departament
de Bioquímica i Biomedicina Molecular, Facultat de Biologia and Institute of Biomedicine (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
- Oncology
Program, National Biomedical Research Institute on Liver and Gastrointestinal
Diseases (CIBER EHD), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - P. Schmidtke
- Departament
de Farmàcia i Tecnologia Farmacèutica, i Fisicoquímica,
Facultat de Farmàcia i Ciències de l′Alimentació
and Institute of Biomedicine (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
| | - C. Estarellas
- Departament
de Nutrició, Ciències de l′Alimentació
i Gastronomia, Facultat de Farmàcia i Ciències de l′Alimentació
and Institute of Biomedicine (IBUB), Campus de l′Alimentació
de Torribera, Universitat de Barcelona, 08921 Santa Coloma
de Gramenet, Spain
| | - X. Barril
- Departament
de Farmàcia i Tecnologia Farmacèutica, i Fisicoquímica,
Facultat de Farmàcia i Ciències de l′Alimentació
and Institute of Biomedicine (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| | - A. Bidon-Chanal
- Departament
de Nutrició, Ciències de l′Alimentació
i Gastronomia, Facultat de Farmàcia i Ciències de l′Alimentació
and Institute of Biomedicine (IBUB), Campus de l′Alimentació
de Torribera, Universitat de Barcelona, 08921 Santa Coloma
de Gramenet, Spain
| | - M. Pastor-Anglada
- Departament
de Bioquímica i Biomedicina Molecular, Facultat de Biologia and Institute of Biomedicine (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
- Oncology
Program, National Biomedical Research Institute on Liver and Gastrointestinal
Diseases (CIBER EHD), Instituto de Salud Carlos III, 28029 Madrid, Spain
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35
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Visualizing multistep elevator-like transitions of a nucleoside transporter. Nature 2017; 545:66-70. [PMID: 28424521 PMCID: PMC5567992 DOI: 10.1038/nature22057] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 03/09/2017] [Indexed: 02/06/2023]
Abstract
Membrane transporters move substrates across the membrane by alternating access of their binding sites between the opposite sides of the membrane. An emerging model of this process is the elevator mechanism, in which a substrate-binding transport domain moves a large distance across the membrane. This mechanism has been characterized by a transition between two states, but the conformational path that leads to the transition is not yet known, largely because the available structural information has been limited to the two end states. Here we present crystal structures of the inward-facing, intermediate, and outward-facing states of a concentrative nucleoside transporter from Neisseria wadsworthii. Notably, we determined the structures of multiple intermediate conformations, in which the transport domain is captured halfway through its elevator motion. Our structures present a trajectory of the conformational transition in the elevator model, revealing multiple intermediate steps and state-dependent conformational changes within the transport domain that are associated with the elevator-like motion.
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36
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Mulinta R, Yao SYM, Ng AML, Cass CE, Young JD. Substituted cysteine accessibility method (SCAM) analysis of the transport domain of human concentrative nucleoside transporter 3 (hCNT3) and other family members reveals features of structural and functional importance. J Biol Chem 2017; 292:9505-9522. [PMID: 28385889 PMCID: PMC5465479 DOI: 10.1074/jbc.m116.743997] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 03/31/2017] [Indexed: 12/13/2022] Open
Abstract
The human SLC28 family of concentrative nucleoside transporter (CNT) proteins has three members: hCNT1, hCNT2, and hCNT3. Na+-coupled hCNT1 and hCNT2 transport pyrimidine and purine nucleosides, respectively, whereas hCNT3 transports both pyrimidine and purine nucleosides utilizing Na+ and/or H+ electrochemical gradients. Escherichia coli CNT family member NupC resembles hCNT1 in permeant selectivity but is H+-coupled. Using heterologous expression in Xenopus oocytes and the engineered cysteine-less hCNT3 protein hCNT3(C-), substituted cysteine accessibility method analysis with the membrane-impermeant thiol reactive reagent p-chloromercuribenzene sulfonate was performed on the transport domain (interfacial helix 2, hairpin 1, putative transmembrane domain (TM) 7, and TM8), as well as TM9 of the scaffold domain of the protein. This systematic scan of the entire C-terminal half of hCNT3(C-) together with parallel studies of the transport domain of wild-type hCNT1 and the corresponding TMs of cysteine-less NupC(C-) yielded results that validate the newly developed structural homology model of CNT membrane architecture for human CNTs, revealed extended conformationally mobile regions within transport-domain TMs, identified pore-lining residues of functional importance, and provided evidence of an emerging novel elevator-type mechanism of transporter function.
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Affiliation(s)
- Ras Mulinta
- From the Membrane Protein Disease Research Group, Departments of Physiology and
| | - Sylvia Y M Yao
- From the Membrane Protein Disease Research Group, Departments of Physiology and
| | - Amy M L Ng
- From the Membrane Protein Disease Research Group, Departments of Physiology and
| | - Carol E Cass
- Oncology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and.,the Cross Cancer Institute, Edmonton, Alberta T6G 2H7, Canada
| | - James D Young
- From the Membrane Protein Disease Research Group, Departments of Physiology and
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37
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Huang W, Zeng X, Shi Y, Liu M. Functional characterization of human equilibrative nucleoside transporter 1. Protein Cell 2017; 8:284-295. [PMID: 27995448 PMCID: PMC5359181 DOI: 10.1007/s13238-016-0350-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 11/04/2016] [Indexed: 12/15/2022] Open
Abstract
Equilibrative nucleoside transporters (ENTs), which facilitate cross-membrane transport of nucleosides and nucleoside-derived drugs, play an important role in the salvage pathways of nucleotide synthesis, cancer chemotherapy, and treatment for virus infections. Functional characterization of ENTs at the molecular level remains technically challenging and hence scant. In this study, we report successful purification and biochemical characterization of human equilibrative nucleoside transporter 1 (hENT1) in vitro. The HEK293F-derived, recombinant hENT1 is homogenous and functionally active in proteoliposome-based counter flow assays. hENT1 transports the substrate adenosine with a Km of 215 ± 34 µmol/L and a Vmax of 578 ± 23.4 nmol mg-1 min-1. Adenosine uptake by hENT1 is competitively inhibited by nitrobenzylmercaptopurine ribonucleoside (NBMPR), nucleosides, deoxynucleosides, and nucleoside-derived anti-cancer and anti-viral drugs. Binding of hENT1 to adenosine, deoxyadenosine, and adenine by isothermal titration calorimetry is in general agreement with results of the competitive inhibition assays. These results validate hENT1 as a bona fide target for potential drug target and serve as a useful basis for future biophysical and structural studies.
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Affiliation(s)
- Weiyun Huang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Xin Zeng
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Minhao Liu
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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Kumar Deokar H, Barch HP, Buolamwini JK. Homology Modeling of Human Concentrative Nucleoside Transporters (hCNTs) and Validation by Virtual Screening and Experimental Testing to Identify Novel hCNT1 Inhibitors. ACTA ACUST UNITED AC 2017; 6. [PMID: 29167753 DOI: 10.4172/2169-0138.1000146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Objective The nucleoside transporter family is an emerging target for cancer, viral and cardiovascular diseases. Due to the difficulty in the expression, isolation and crystallization of membrane proteins, there is a lack of structural information on any of the mammalian and for that matter the human proteins. Thus the objective of this study was to build homology models for the three cloned concentrative nucleoside transporters hCNT1, hCNT2 and hCNT3 and validate them for screening towards the discovery of much needed inhibitors and probes. Methods The recently reported crystal structure of the Vibrio cholerae concentrative nucleoside transporter (vcCNT), has satisfactory similarity to the human CNT orthologues and was thus used as a template to build homology models of all three hCNTs. The Schrödinger modeling suite was used for the exercise. External validation of the homology models was carried out by docking a set of recently reported known hCNT1 nucleoside class inhibitors at the putative binding site using induced fit docking (IDF) methodology with the Glide docking program. Then, the hCNT1 homology model was subsequently used to conduct a virtual screening of a 360,000 compound library, and 172 compounds were obtained and biologically evaluated for hCNT 1, 2 and 3 inhibitory potency and selectivity. Results Good quality homology models were obtained for all three hCNTs as indicated by interrogation for various structural parameters and also external validated by docking of known inhibitors. The IDF docking results showed good correlations between IDF scores and inhibitory activities; particularly for hCNT1. From the top 0.1% of compounds ranked by virtual screening with the hCNT1 homology model, 172 compounds selected and tested for against hCNT1, hCNT2 and hCNT3, yielded 14 new inhibitors (hits) of (i.e., 8% success rate). The most active compound exhibited an IC50 of 9.05 μM, which shows a greater than 25-fold higher potency than phlorizin the standard CNT inhibitor (IC50 of 250 μM). Conclusion We successfully undertook homology modeling and validation for all human concentrative nucleoside transporters (hCNT 1, 2 and 3). The proof-of-concept that these models are promising for virtual screening to identify potent and selective inhibitors was also obtained using the hCNT1 model. Thus we identified a novel potent hCNT1 inhibitor that is more potent and more selective than the standard inhibitor phlorizin. The other hCNT1 hits also mostly exhibited selectivity. These homology models should be useful for virtual screening to identify novel hCNT inhibitors, as well as for optimization of hCNT inhibitors.
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Affiliation(s)
- Hemant Kumar Deokar
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Suite 327, Memphis, Tennessee, 38163, USA.,Department of Pharmaceutical Sciences, College of Pharmacy, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, 60064, USA
| | - Hilaire Playa Barch
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Suite 327, Memphis, Tennessee, 38163, USA
| | - John K Buolamwini
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 847 Monroe Avenue, Suite 327, Memphis, Tennessee, 38163, USA.,Department of Pharmaceutical Sciences, College of Pharmacy, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois, 60064, USA
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Lapponi MJ, Rivero CW, Zinni MA, Britos CN, Trelles JA. New developments in nucleoside analogues biosynthesis: A review. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2016.08.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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40
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Dissection of Transporter Function: From Genetics to Structure. Trends Genet 2016; 32:576-590. [DOI: 10.1016/j.tig.2016.06.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 06/20/2016] [Accepted: 06/21/2016] [Indexed: 12/20/2022]
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The bacterial dicarboxylate transporter VcINDY uses a two-domain elevator-type mechanism. Nat Struct Mol Biol 2016; 23:256-63. [PMID: 26828963 PMCID: PMC5215794 DOI: 10.1038/nsmb.3166] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 12/30/2015] [Indexed: 11/11/2022]
Abstract
Secondary transporters use alternating access mechanisms to couple uphill substrate movement to downhill ion flux. Most known transporters utilize a “rocking bundle” motion, where the protein moves around an immobile substrate binding site. However, the glutamate transporter homolog, GltPh, translocates its substrate binding site vertically across the membrane, an “elevator” mechanism. Here, we used the “repeat swap” approach to computationally predict the outward-facing state of the Na+/succinate transporter VcINDY, from Vibrio cholerae. Our model predicts a substantial “elevator”-like movement of vcINDY’s substrate binding site, with a vertical translation of ~15 Å and a rotation of ~43°; multiple disulfide crosslinks which completely inhibit transport provide experimental confirmation and demonstrate that such movement is essential. In contrast, crosslinks across the VcINDY dimer interface preserve transport, revealing an absence of large scale coupling between protomers.
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Gumpenberger T, Vorkapic D, Zingl FG, Pressler K, Lackner S, Seper A, Reidl J, Schild S. Nucleoside uptake in Vibrio cholerae and its role in the transition fitness from host to environment. Mol Microbiol 2015. [PMID: 26202476 DOI: 10.1111/mmi.13143] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
As it became evident recently, extracellular DNA could be a versatile nutrient source of the facultative pathogen Vibrio cholerae along the different stages of its life cycle. By the use of two extracellular nucleases and periplasmic phosphatases, V. cholerae degrades extracellular DNA to nucleosides. In this study, we investigated the nucleoside uptake via identification and characterization of VCA0179, VC1953 and VC2352 representing the three nucleoside transport systems in V. cholerae. Based on our results VC2352 seems to be the dominant nucleoside transporter. Nevertheless, all three transporters are functional and can contribute to the utilization of nucleosides as a sole source of carbon or nitrogen. We found that the transcriptional activity of these three distal genes is equally promoted or antagonized by CRP or CytR respectively. Finally, mutants impaired for nucleoside uptake exhibit decreased transition fitness from the host into low carbon environments along the life cycle of V. cholerae.
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Affiliation(s)
- Tanja Gumpenberger
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Dina Vorkapic
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Franz G Zingl
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Katharina Pressler
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Stefanie Lackner
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Andrea Seper
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Joachim Reidl
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
| | - Stefan Schild
- Institute of Molecular Biosciences, University of Graz, Humboldtstr. 50, Graz, 8010, Austria
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Vergara-Jaque A, Fenollar-Ferrer C, Kaufmann D, Forrest LR. Repeat-swap homology modeling of secondary active transporters: updated protocol and prediction of elevator-type mechanisms. Front Pharmacol 2015; 6:183. [PMID: 26388773 PMCID: PMC4560100 DOI: 10.3389/fphar.2015.00183] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 08/13/2015] [Indexed: 12/04/2022] Open
Abstract
Secondary active transporters are critical for neurotransmitter clearance and recycling during synaptic transmission and uptake of nutrients. These proteins mediate the movement of solutes against their concentration gradients, by using the energy released in the movement of ions down pre-existing concentration gradients. To achieve this, transporters conform to the so-called alternating-access hypothesis, whereby the protein adopts at least two conformations in which the substrate binding sites are exposed to one or other side of the membrane, but not both simultaneously. Structures of a bacterial homolog of neuronal glutamate transporters, GltPh, in several different conformational states have revealed that the protein structure is asymmetric in the outward- and inward-open states, and that the conformational change connecting them involves a elevator-like movement of a substrate binding domain across the membrane. The structural asymmetry is created by inverted-topology repeats, i.e., structural repeats with similar overall folds whose transmembrane topologies are related to each other by two-fold pseudo-symmetry around an axis parallel to the membrane plane. Inverted repeats have been found in around three-quarters of secondary transporter folds. Moreover, the (a)symmetry of these systems has been successfully used as a bioinformatic tool, called “repeat-swap modeling” to predict structural models of a transporter in one conformation using the known structure of the transporter in the complementary conformation as a template. Here, we describe an updated repeat-swap homology modeling protocol, and calibrate the accuracy of the method using GltPh, for which both inward- and outward-facing conformations are known. We then apply this repeat-swap homology modeling procedure to a concentrative nucleoside transporter, VcCNT, which has a three-dimensional arrangement related to that of GltPh. The repeat-swapped model of VcCNT predicts that nucleoside transport also occurs via an elevator-like mechanism.
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Affiliation(s)
- Ariela Vergara-Jaque
- Computational Structural Biology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke - National Institutes of Health, Bethesda, MD USA
| | - Cristina Fenollar-Ferrer
- Computational Structural Biology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke - National Institutes of Health, Bethesda, MD USA
| | - Desirée Kaufmann
- Computational Structural Biology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke - National Institutes of Health, Bethesda, MD USA
| | - Lucy R Forrest
- Computational Structural Biology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke - National Institutes of Health, Bethesda, MD USA
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Multifaceted roles of extracellular DNA in bacterial physiology. Curr Genet 2015; 62:71-9. [PMID: 26328805 PMCID: PMC4723616 DOI: 10.1007/s00294-015-0514-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 08/20/2015] [Accepted: 08/21/2015] [Indexed: 11/08/2022]
Abstract
In textbooks, DNA is generally defined as the universal storage material for genetic information in all branches of life. Beyond this important intracellular role, DNA can also be present outside of living cells and is an abundant biopolymer in aquatic and terrestrial ecosystems. The origin of extracellular DNA in such ecological niches is diverse: it can be actively secreted or released by prokaryotic and eukaryotic cells by means of autolysis, apoptosis, necrosis, bacterial secretion systems or found in association with extracellular bacterial membrane vesicles. Especially for bacteria, extracellular DNA represents a significant and convenient element that can be enzymatically modulated and utilized for multiple purposes. Herein, we discuss briefly the main origins of extracellular DNA and the most relevant roles for the bacterial physiology, such as biofilm formation, nutrient source, antimicrobial means and horizontal gene transfer.
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Lin L, Yee SW, Kim RB, Giacomini KM. SLC transporters as therapeutic targets: emerging opportunities. Nat Rev Drug Discov 2015; 14:543-60. [PMID: 26111766 DOI: 10.1038/nrd4626] [Citation(s) in RCA: 512] [Impact Index Per Article: 56.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Solute carrier (SLC) transporters - a family of more than 300 membrane-bound proteins that facilitate the transport of a wide array of substrates across biological membranes - have important roles in physiological processes ranging from the cellular uptake of nutrients to the absorption of drugs and other xenobiotics. Several classes of marketed drugs target well-known SLC transporters, such as neurotransmitter transporters, and human genetic studies have provided powerful insight into the roles of more-recently characterized SLC transporters in both rare and common diseases, indicating a wealth of new therapeutic opportunities. This Review summarizes knowledge on the roles of SLC transporters in human disease, describes strategies to target such transporters, and highlights current and investigational drugs that modulate SLC transporters, as well as promising drug targets.
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Affiliation(s)
- Lawrence Lin
- Department of Bioengineering and Therapeutic Sciences, Schools of Pharmacy and Medicine, University of California San Francisco, San Francisco, California 94158, USA
| | - Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, Schools of Pharmacy and Medicine, University of California San Francisco, San Francisco, California 94158, USA
| | - Richard B Kim
- Division of Clinical Pharmacology, Department of Medicine, University of Western Ontario, London Health Science Centre, London, Ontario N6A 5A5, Canada
| | - Kathleen M Giacomini
- 1] Department of Bioengineering and Therapeutic Sciences, Schools of Pharmacy and Medicine, University of California San Francisco, San Francisco, California 94158, USA. [2] Institute for Human Genetics, University of California San Francisco, San Francisco, California 94158, USA
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Johnson ZL, Lee SY. Liposome reconstitution and transport assay for recombinant transporters. Methods Enzymol 2015; 556:373-83. [PMID: 25857791 DOI: 10.1016/bs.mie.2014.11.048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Secondary active transporters are responsible for the cellular uptake of many biologically important molecules, including neurotransmitters, nutrients, and drugs. Because of their physiological and clinical importance, a method for assessing their transport activity in vitro is necessary to gain a better understanding of how these transporters function at the molecular level. In this chapter, we describe a protocol for reconstituting the concentrative nucleoside transporter from Vibrio cholerae into proteoliposomes. We then describe a radiolabeled substrate uptake assay that can be used to functionally characterize the transporter. These methods are relatively common and can be applied to other secondary active transporters, with or without some modification.
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Affiliation(s)
- Zachary Lee Johnson
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, USA
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, USA.
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