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Zhao J, Zhang M, Hui W, Zhang Y, Wang J, Wang S, Kwok LY, Kong J, Zhang H, Zhang W. Roles of adenine methylation in the physiology of Lacticaseibacillus paracasei. Nat Commun 2023; 14:2635. [PMID: 37149616 PMCID: PMC10164179 DOI: 10.1038/s41467-023-38291-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 04/21/2023] [Indexed: 05/08/2023] Open
Abstract
Lacticaseibacillus paracasei is an economically important bacterial species, used in the food industry and as a probiotic. Here, we investigate the roles of N6-methyladenine (6mA) modification in L. paracasei using multi-omics and high-throughput chromosome conformation capture (Hi-C) analyses. The distribution of 6mA-modified sites varies across the genomes of 28 strains, and appears to be enriched near genes involved in carbohydrate metabolism. A pglX mutant, defective in 6mA modification, shows transcriptomic alterations but only modest changes in growth and genomic spatial organization.
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Affiliation(s)
- Jie Zhao
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Meng Zhang
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Wenyan Hui
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Yue Zhang
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Jing Wang
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Shaojing Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Lai-Yu Kwok
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Jian Kong
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Heping Zhang
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, 010018, China
- Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Wenyi Zhang
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, 010018, China.
- Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, 010018, China.
- Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China.
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Wang M, He J, Li S, Cai Q, Zhang K, She J. Structural basis of vitamin C recognition and transport by mammalian SVCT1 transporter. Nat Commun 2023; 14:1361. [PMID: 36914666 PMCID: PMC10011568 DOI: 10.1038/s41467-023-37037-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 02/28/2023] [Indexed: 03/15/2023] Open
Abstract
Vitamin C (L-ascorbic acid) is an essential nutrient for human health, and its deficiency has long been known to cause scurvy. Sodium-dependent vitamin C transporters (SVCTs) are responsible for vitamin C uptake and tissue distribution in mammals. Here, we present cryogenic electron microscopy structures of mouse SVCT1 in both the apo and substrate-bound states. Mouse SVCT1 forms a homodimer with each protomer containing a core domain and a gate domain. The tightly packed extracellular interfaces between the core domain and gate domain stabilize the protein in an inward-open conformation for both the apo and substrate-bound structures. Vitamin C binds at the core domain of each subunit, and two potential sodium ions are identified near the binding site. The coordination of sodium ions by vitamin C explains their coupling transport. SVCTs probably deliver substrate through an elevator mechanism in combination with local structural arrangements. Altogether, our results reveal the molecular mechanism by which SVCTs recognize vitamin C and lay a foundation for further mechanistic studies on SVCT substrate transport.
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Affiliation(s)
- Mingxing Wang
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China
| | - Jin He
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China
| | - Shanshan Li
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China
| | - Qianwen Cai
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Kaiming Zhang
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China.
| | - Ji She
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China.
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3
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Muñoz-Montesino C, Peña E, Roa FJ, Sotomayor K, Escobar E, Rivas CI. Transport of Vitamin C in Cancer. Antioxid Redox Signal 2021; 35:61-74. [PMID: 33607936 DOI: 10.1089/ars.2020.8166] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Significance: Vitamin C is a powerful antioxidant that has an intricate relationship with cancer and has been studied for more than 60 years. However, the specific mechanisms that allow malignant cells to uptake, metabolize, and compartmentalize vitamin C remain unclear. In normal human cells, two different transporter systems are responsible for its acquisition: glucose transporters (GLUTs) transport the oxidized form of vitamin C (dehydroascorbic acid) and sodium-coupled ascorbic acid transporters (SVCTs) transport the reduced form (ascorbic acid [AA]). In this study, we review the mechanisms described for vitamin C uptake and metabolization in cancer. Recent Advances: Several studies performed recently in vivo and in vitro have provided the scientific community a better understanding of the differential capacities of cancer cells to acquire vitamin C: tumors from different origins do not express SVCTs in the plasma membrane and are only able to acquire vitamin C in its oxidized form. Interestingly, cancer cells differentially express a mitochondrial form of SVCT2. Critical Issues: Why tumors have reduced AA uptake capacity at the plasma membrane, but develop the capacity of AA transport within mitochondria, remains a mystery. However, it shows that understanding vitamin C physiology in tumor survival might be key to decipher the controversies in its relationship with cancer. Future Directions: A comprehensive analysis of the mechanisms by which cancer cells acquire, compartmentalize, and use vitamin C will allow the design of new therapeutic approaches in human cancer. Antioxid. Redox Signal. 35, 61-74.
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Affiliation(s)
- Carola Muñoz-Montesino
- Departamento de Fisiología and Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Eduardo Peña
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Francisco J Roa
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Kirsty Sotomayor
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Elizabeth Escobar
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Coralia I Rivas
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
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Jiaranaikulwanitch J, Pandith H, Tadtong S, Thammarat P, Jiranusornkul S, Chauthong N, Nilkosol S, Vajragupta O. Novel Multifunctional Ascorbic Triazole Derivatives for Amyloidogenic Pathway Inhibition, Anti-Inflammation, and Neuroprotection. Molecules 2021; 26:molecules26061562. [PMID: 33809092 PMCID: PMC7999550 DOI: 10.3390/molecules26061562] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/02/2021] [Accepted: 03/09/2021] [Indexed: 01/25/2023] Open
Abstract
Alzheimer's disease (AD) is a common neurodegenerative disorder. The number of patients with AD is projected to reach 152 million by 2050. Donepezil, rivastigmine, galantamine, and memantine are the only four drugs currently approved by the United States Food and Drug Administration for AD treatment. However, these drugs can only alleviate AD symptoms. Thus, this research focuses on the discovery of novel lead compounds that possess multitarget regulation of AD etiopathology relating to amyloid cascade. The ascorbic acid structure has been designated as a core functional domain due to several characteristics, including antioxidant activities, amyloid aggregation inhibition, and the ability to be transported to the brain and neurons. Multifunctional ascorbic derivatives were synthesized by copper (I)-catalyzed azide-alkyne cycloaddition reaction (click chemistry). The in vitro and cell-based assays showed that compounds 2c and 5c exhibited prominent multifunctional activities as beta-secretase 1 inhibitors, amyloid aggregation inhibitors, and antioxidant, neuroprotectant, and anti-inflammatory agents. Significant changes in activities promoting neuroprotection and anti-inflammation were observed at a considerably low concentration at a nanomolar level. Moreover, an in silico study showed that compounds 2c and 5c were capable of being permeated across the blood-brain barrier by sodium-dependent vitamin C transporter-2.
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Affiliation(s)
- Jutamas Jiaranaikulwanitch
- Innovation Center for Holistic Health, Nutraceuticals, and Cosmeceuticals, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand; (P.T.); (S.J.); (N.C.); (S.N.)
- Correspondence: ; Tel.: +66-5394-4382
| | - Hataichanok Pandith
- Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand;
| | - Sarin Tadtong
- Department of Pharmacognosy, Faculty of Pharmacy, Srinakharinwirot University, Nakhonnayok 26120, Thailand;
| | - Phanit Thammarat
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand; (P.T.); (S.J.); (N.C.); (S.N.)
| | - Supat Jiranusornkul
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand; (P.T.); (S.J.); (N.C.); (S.N.)
| | - Nattapong Chauthong
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand; (P.T.); (S.J.); (N.C.); (S.N.)
| | - Supitcha Nilkosol
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand; (P.T.); (S.J.); (N.C.); (S.N.)
| | - Opa Vajragupta
- Office of Research Affairs, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand;
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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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6
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Jeckelmann JM, Erni B. The mannose phosphotransferase system (Man-PTS) - Mannose transporter and receptor for bacteriocins and bacteriophages. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183412. [PMID: 32710850 DOI: 10.1016/j.bbamem.2020.183412] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/08/2020] [Accepted: 07/14/2020] [Indexed: 02/06/2023]
Abstract
Mannose transporters constitute a superfamily (Man-PTS) of the Phosphoenolpyruvate Carbohydrate Phosphotransferase System (PTS). The membrane complexes are homotrimers of protomers consisting of two subunits, IIC and IID. The two subunits without recognizable sequence similarity assume the same fold, and in the protomer are structurally related by a two fold pseudosymmetry axis parallel to membrane-plane (Liu et al. (2019) Cell Research 29 680). Two reentrant loops and two transmembrane helices of each subunit together form the N-terminal transport domain. Two three-helix bundles, one of each subunit, form the scaffold domain. The protomer is stabilized by a helix swap between these bundles. The two C-terminal helices of IIC mediate the interprotomer contacts. PTS occur in bacteria and archaea but not in eukaryotes. Man-PTS are abundant in Gram-positive bacteria living on carbohydrate rich mucosal surfaces. A subgroup of IICIID complexes serve as receptors for class IIa bacteriocins and as channel for the penetration of bacteriophage lambda DNA across the inner membrane. Some Man-PTS are associated with host-pathogen and -symbiont processes.
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Affiliation(s)
- Jean-Marc Jeckelmann
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.
| | - Bernhard Erni
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland.
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7
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Functional (un)cooperativity in elevator transport proteins. Biochem Soc Trans 2020; 48:1047-1055. [PMID: 32573703 DOI: 10.1042/bst20190970] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 11/17/2022]
Abstract
The activity of enzymes is subject to regulation at multiple levels. Cooperativity, the interconnected behavior of active sites within a protein complex, directly affects protein activity. Cooperativity is a mode of regulation that requires neither extrinsic factors nor protein modifications. Instead, it allows enzymes themselves to modulate reaction rates. Cooperativity is an important regulatory mechanism in soluble proteins, but also examples of cooperative membrane proteins have been described. In this review, we summarize the current knowledge on interprotomer cooperativity in elevator-type proteins, a class of membrane transporters characterized by large rigid-body movements perpendicular to the membrane, and highlight well-studied examples and experimental approaches.
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Transporters of glucose and other carbohydrates in bacteria. Pflugers Arch 2020; 472:1129-1153. [PMID: 32372286 DOI: 10.1007/s00424-020-02379-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 12/18/2022]
Abstract
Glucose arguably is the most important energy carrier, carbon source for metabolites and building block for biopolymers in all kingdoms of life. The proper function of animal organs and tissues depends on the continuous supply of glucose from the bloodstream. Most animals can resorb only a small number of monosaccharides, mostly glucose, galactose and fructose, while all other sugars oligosaccharides and dietary fibers are degraded and metabolized by the microbiota of the lower intestine. Bacteria, in contrast, are omnivorous. They can import and metabolize structurally different sugars and, as a consortium of different species, utilize almost any sugar, sugar derivative and oligosaccharide occurring in nature. Bacteria have membrane transport systems for the uptake of sugars against steep concentration gradients energized by ATP, the proton motive force and the high energy glycolytic intermediate phosphoenolpyruvate (PEP). Different uptake mechanisms and the broad range of overlapping substrate specificities allow bacteria to quickly adapt to and colonize changing environments. Here, we review the structures and mechanisms of bacterial representatives of (i) ATP-dependent cassette (ABC) transporters, (ii) major facilitator (MFS) superfamily proton symporters, (iii) sodium solute symporters (SSS) and (iv) enzyme II integral membrane subunits of the bacterial PEP-dependent phosphotransferase system (PTS). We give a short overview on the distribution of transporter genes and their phylogenetic relationship in different bacterial species. Some sugar transporters are hijacked for import of bacteriophage DNA and antibacterial toxins (bacteriocins) and they facilitate the penetration of polar antibiotics. Finally, we describe how the expression and activity of certain sugar transporters are controlled in response to the availability of sugars and how the presence and uptake of sugars may affect pathogenicity and host-microbiota interactions.
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Aboulwafa M, Zhang Z, Saier MH. Protein:Protein interactions in the cytoplasmic membrane apparently influencing sugar transport and phosphorylation activities of the e. coli phosphotransferase system. PLoS One 2019; 14:e0219332. [PMID: 31751341 PMCID: PMC6872149 DOI: 10.1371/journal.pone.0219332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 10/13/2019] [Indexed: 01/05/2023] Open
Abstract
The multicomponent phosphoenolpyruvate (PEP)-dependent sugar-transporting phosphotransferase system (PTS) in Escherichia coli takes up sugar substrates from the medium and concomitantly phosphorylates them, releasing sugar phosphates into the cytoplasm. We have recently provided evidence that many of the integral membrane PTS permeases interact with the fructose PTS (FruA/FruB) [1]. However, the biochemical and physiological significance of this finding was not known. We have carried out molecular genetic/biochemical/physiological studies that show that interactions of the fructose PTS often enhance, but sometimes inhibit the activities of other PTS transporters many fold, depending on the target PTS system under study. Thus, the glucose (Glc), mannose (Man), mannitol (Mtl) and N-acetylglucosamine (NAG) permeases exhibit enhanced in vivo sugar transport and sometimes in vitro PEP-dependent sugar phosphorylation activities while the galactitol (Gat) and trehalose (Tre) systems show inhibited activities. This is observed when the fructose system is induced to high levels and prevented when the fruA/fruB genes are deleted. Overexpression of the fruA and/or fruB genes in the absence of fructose induction during growth also enhances the rates of uptake of other hexoses. The β-galactosidase activities of man, mtl, and gat-lacZ transcriptional fusions and the sugar-specific transphosphorylation activities of these enzyme transporters were not affected either by frustose induction or by fruAB overexpression, showing that the rates of synthesis of the target PTS permeases were not altered. We thus suggest that specific protein-protein interactions within the cytoplasmic membrane regulate transport in vivo (and sometimes the PEP-dependent phosphorylation activities in vitro) of PTS permeases in a physiologically meaningful way that may help to provide a hierarchy of preferred PTS sugars. These observations appear to be applicable in principle to other types of transport systems as well.
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Affiliation(s)
- Mohammad Aboulwafa
- Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA, United States of America
- Department of Microbiology and Immunology, Faculty of Pharmacy, Ain Shams University, Abbassia, Cairo, Egypt
| | - Zhongge Zhang
- Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA, United States of America
| | - Milton H. Saier
- Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA, United States of America
- * E-mail:
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Balandin SV, Sheremeteva EV, Ovchinnikova TV. Pediocin-Like Antimicrobial Peptides of Bacteria. BIOCHEMISTRY (MOSCOW) 2019; 84:464-478. [PMID: 31234762 DOI: 10.1134/s000629791905002x] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bacteriocins are bacterial antimicrobial peptides that, unlike classical peptide antibiotics, are products of ribosomal synthesis and usually have a narrow spectrum of antibacterial activity against species closely related to the producers. Pediocin-like bacteriocins (PLBs) belong to the class IIa of the bacteriocins of Gram-positive bacteria. PLBs possess high activity against pathogenic bacteria from Listeria and Enterococcus genera. Molecular target for PLBs is a membrane protein complex - bacterial mannose-phosphotransferase. PLBs can be synthesized by components of symbiotic microflora and participate in the maintenance of homeostasis in various compartments of the digestive tract and on the surface of epithelial tissues contacting the external environment. PLBs could give a rise to a new group of antibiotics of narrow spectrum of activity.
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Affiliation(s)
- S V Balandin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - E V Sheremeteva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - T V Ovchinnikova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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11
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Structure of the mannose transporter of the bacterial phosphotransferase system. Cell Res 2019; 29:680-682. [PMID: 31209249 DOI: 10.1038/s41422-019-0194-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 05/14/2019] [Indexed: 12/17/2022] Open
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12
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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Jeckelmann JM, Erni B. Carbohydrate Transport by Group Translocation: The Bacterial Phosphoenolpyruvate: Sugar Phosphotransferase System. Subcell Biochem 2019; 92:223-274. [PMID: 31214989 DOI: 10.1007/978-3-030-18768-2_8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Bacterial Phosphoenolpyruvate (PEP) : Sugar Phosphotransferase System (PTS) mediates the uptake and phosphorylation of carbohydrates, and controls the carbon- and nitrogen metabolism in response to the availability of sugars. PTS occur in eubacteria and in a few archaebacteria but not in animals and plants. All PTS comprise two cytoplasmic phosphotransferase proteins (EI and HPr) and a species-dependent, variable number of sugar-specific enzyme II complexes (IIA, IIB, IIC, IID). EI and HPr transfer phosphorylgroups from PEP to the IIA units. Cytoplasmic IIA and IIB units sequentially transfer phosphates to the sugar, which is transported by the IIC and IICIID integral membrane protein complexes. Phosphorylation by IIB and translocation by IIC(IID) are tightly coupled. The IIC(IID) sugar transporters of the PTS are in the focus of this review. There are four structurally different PTS transporter superfamilies (glucose, glucitol, ascorbate, mannose) . Crystal structures are available for transporters of two superfamilies: bcIICmal (MalT, 5IWS, 6BVG) and bcIICchb (ChbC, 3QNQ) of B. subtilis from the glucose family, and IICasc (UlaA, 4RP9, 5ZOV) of E. coli from the ascorbate superfamily . They are homodimers and each protomer has an independent transport pathway which functions by an elevator-type alternating-access mechanism. bcIICmal and bcIICchb have the same fold, IICasc has a completely different fold. Biochemical and biophysical data accumulated in the past with the transporters for mannitol (IICBAmtl) and glucose (IICBglc) are reviewed and discussed in the context of the bcIICmal crystal structures. The transporters of the mannose superfamily are dimers of protomers consisting of a IIC and a IID protein chain. The crystal structure is not known and the topology difficult to predict. Biochemical data indicate that the IICIID complex employs a different transport mechanism . Species specific IICIID serve as a gateway for the penetration of bacteriophage lambda DNA across, and insertion of class IIa bacteriocins into the inner membrane. PTS transporters are inserted into the membrane by SecYEG translocon and have specific lipid requirements. Immunoelectron- and fluorescence microscopy indicate a non-random distribution and supramolecular complexes of PTS proteins.
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Affiliation(s)
- Jean-Marc Jeckelmann
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012, Bern, Switzerland.
| | - Bernhard Erni
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012, Bern, Switzerland
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14
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Luo P, Dai S, Zeng J, Duan J, Shi H, Wang J. Inward-facing conformation of l-ascorbate transporter suggests an elevator mechanism. Cell Discov 2018; 4:35. [PMID: 30038796 PMCID: PMC6048161 DOI: 10.1038/s41421-018-0037-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 05/03/2018] [Accepted: 05/08/2018] [Indexed: 11/09/2022] Open
Abstract
Various bacteria can ferment vitamin C (l-ascorbate) under anaerobic conditions via the phosphoenolpyruvate-dependent phosphotransferase system (PTS). The PTSasc system is composed of two soluble energy-coupling proteins (EI and HPr) and an enzyme II complex (EIIA, EIIB, and EIIC) for the anaerobic uptake of ascorbate and its phosphorylation to l-ascorbate 6-phosphate in vivo. Crystal structures of the ascorbate-bound EIIC component from Escherichia coli are available in outward-open and occluded conformations, suggesting a possible elevator mechanism of membrane transport. Despite these advances, it remains unclear how EIIC actually transports the substrate across the membrane and interacts with EIIB, which transfers its phosphate group to the EIIC-embedding ascorbate. Here, we present the crystal structure of the EIICasc component from Pasteurella multocida in the inward-facing conformation. By comparing three conformational states, we confirmed the original proposed model: the ascorbate translocation can be achieved by a rigid-body movement of the substrate-binding core domain relative to the V motif domain, which brings along the transmembrane helices TM2 and TM7 of the V motif domain to undergo a winding at the pivotal positions. Together with an in vivo transport assay, we completed the picture of the transport cycle of the ascorbate superfamily of membrane-spanning EIIC components of the PTS system.
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Affiliation(s)
- Ping Luo
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Shuliu Dai
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jianwei Zeng
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jinsong Duan
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Hui Shi
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jiawei Wang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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15
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Structure of an EIIC sugar transporter trapped in an inward-facing conformation. Proc Natl Acad Sci U S A 2018; 115:5962-5967. [PMID: 29784777 DOI: 10.1073/pnas.1800647115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The phosphoenolpyruvate-dependent phosphotransferase system (PTS) transports sugar into bacteria and phosphorylates the sugar for metabolic consumption. The PTS is important for the survival of bacteria and thus a potential target for antibiotics, but its mechanism of sugar uptake and phosphorylation remains unclear. The PTS is composed of multiple proteins, and the membrane-embedded Enzyme IIC (EIIC) component transports sugars across the membrane. Crystal structures of two members of the glucose superfamily of EIICs, bcChbC and bcMalT, were solved in the inward-facing and outward-facing conformations, and the structures suggest that sugar translocation could be achieved by movement of a structured domain that contains the sugar-binding site. However, different conformations have not been captured on the same transporter to allow precise description of the conformational changes. Here we present a crystal structure of bcMalT trapped in an inward-facing conformation by a mercury ion that bridges two strategically placed cysteine residues. The structure allows direct comparison of the outward- and inward-facing conformations and reveals a large rigid-body motion of the sugar-binding domain and other conformational changes that accompany the rigid-body motion. All-atom molecular dynamics simulations show that the inward-facing structure is stable with or without the cross-linking. The conformational changes were further validated by single-molecule Föster resonance energy transfer (smFRET). Combined, these results establish the elevator-type mechanism of transport in the glucose superfamily of EIIC transporters.
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16
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Wang Y, Feng Y, Cao X, Liu Y, Xue S. Insights into the molecular mechanism of dehalogenation catalyzed by D-2-haloacid dehalogenase from crystal structures. Sci Rep 2018; 8:1454. [PMID: 29362453 PMCID: PMC5780510 DOI: 10.1038/s41598-017-19050-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 12/17/2017] [Indexed: 11/09/2022] Open
Abstract
D-2-haloacid dehalogenases (D-DEXs) catalyse the hydrolytic dehalogenation of D-2-haloacids, releasing halide ions and producing the corresponding 2-hydroxyacids. A structure-guided elucidation of the catalytic mechanism of this dehalogenation reaction has not been reported yet. Here, we report the catalytic mechanism of a D-DEX, HadD AJ1 from Pseudomonas putida AJ1/23, which was elucidated by X-ray crystallographic analysis and the H218O incorporation experiment. HadD AJ1 is an α-helical hydrolase that forms a homotetramer with its monomer including two structurally axisymmetric repeats. The product-bound complex structure was trapped with L-lactic acid in the active site, which is framed by the structurally related helices between two repeats. Site-directed mutagenesis confirmed the importance of the residues lining the binding pocket in stabilizing the enzyme-substrate complex. Asp205 acts as a key catalytic residue and is responsible for activating a water molecule along with Asn131. Then, the hydroxyl group of the water molecule directly attacks the C2 atom of the substrate to release the halogen ion instead of forming an enzyme-substrate ester intermediate as observed in L-2-haloacid dehalogenases. The newly revealed structural and mechanistic information on D-DEX may inspire structure-based mutagenesis to engineer highly efficient haloacid dehalogenases.
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Affiliation(s)
- Yayue Wang
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanbin Feng
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Xupeng Cao
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Yinghui Liu
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Song Xue
- Marine Bioengineering Group, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
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17
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Agrocin 108 is a 5'-cytidine nucleotide bacteriocin containing a carbocyclic phosphoryl-ascorbate group. J Antibiot (Tokyo) 2018; 71:438-446. [PMID: 29348528 DOI: 10.1038/s41429-017-0014-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/26/2017] [Accepted: 12/01/2017] [Indexed: 12/21/2022]
Abstract
Agrocin 108 is a 3'-O-β-D-xylopyranosyl-cytidine-5'-O-phosphodiester of an ascorbate-carbocyclic cyclopentenone analogue, with bacteriocin-like properties. This bacteriocin exhibits orders of magnitude greater than the inhibition zone diameter towards the indicator strain than either ampicillin or streptomycin. It has been isolated from cultures of Rhizobium rhizogenes strain K108. The structure of the agrocin 108 without detail, has been previously published. We now report a detailed structure elucidation, including the hitherto undetermined residual 5'-phospho-diester fragment by a combination of 1D and 2D NMR studies at various pH values in H2O/D2O, high resolution MS, pKa determination, and chemical degradation.
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18
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Chothe PP, Czuba LC, Moore RH, Swaan PW. Human bile acid transporter ASBT (SLC10A2) forms functional non-covalent homodimers and higher order oligomers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:645-653. [PMID: 29198943 DOI: 10.1016/j.bbamem.2017.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 11/22/2017] [Accepted: 11/27/2017] [Indexed: 12/28/2022]
Abstract
The human apical sodium-dependent bile acid transporter, hASBT/SLC10A2, plays a central role in cholesterol homeostasis via the efficient reabsorption of bile acids from the distal ileum. hASBT has been shown to self-associate in higher order complexes, but while the functional role of endogenous cysteines has been reported, their implication in the oligomerization of hASBT remains unresolved. Here, we determined the self-association architecture of hASBT by site-directed mutagenesis combined with biochemical, immunological and functional approaches. We generated a cysteine-less form of hASBT by creating point mutations at all 13 endogenous cysteines in a stepwise manner. Although Cysless hASBT had significantly reduced function correlated with lowered surface expression, it featured an extra glycosylation site that facilitated its differentiation from wt-hASBT on immunoblots. Decreased protein expression was associated with instability and subsequent proteasome-dependent degradation of Cysless hASBT protein. Chemical cross-linking of wild-type and Cysless species revealed that hASBT exists as an active dimer and/or higher order oligomer with apparently no requirement for endogenous cysteine residues. This was further corroborated by co-immunoprecipitation of differentially tagged (HA-, Flag-) wild-type and Cysless hASBT. Finally, Cysless hASBT exhibited a dominant-negative effect when co-expressed with wild-type hASBT which validated heterodimerization/oligomerization at the functional level. Combined, our data conclusively demonstrate the functional existence of hASBT dimers and higher order oligomers irrespective of cysteine-mediated covalent bonds, thereby providing greater understanding of its topological assembly at the membrane surface.
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Affiliation(s)
- Paresh P Chothe
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA
| | - Lindsay C Czuba
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA
| | - Robyn H Moore
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA
| | - Peter W Swaan
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA.
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19
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Vastermark A, Saier MH. Time to Stop Holding the Elevator: A New Piece of the Transport Protein Mechanism Puzzle. Structure 2017; 24:845-6. [PMID: 27276425 DOI: 10.1016/j.str.2016.05.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In this issue of Structure, McCoy et al. (2016) describe the 2.55-Å X-ray structure of the outward-facing occluded conformation of the Bacillus cereus maltose transporter MalT. This structure represents the penultimate piece needed to complete the picture of the transport cycle of the glucose superfamily of membrane-spanning EIIC components.
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Affiliation(s)
- Ake Vastermark
- Department of Molecular Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA
| | - Milton H Saier
- Department of Molecular Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA.
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20
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Electron crystallography reveals that substrate release from the PTS IIC glucose transporter is coupled to a subtle conformational change. J Struct Biol 2017; 199:39-45. [PMID: 28522226 DOI: 10.1016/j.jsb.2017.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/05/2017] [Accepted: 05/13/2017] [Indexed: 01/13/2023]
Abstract
The phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) is a structurally and functionally complex system that mediates sugar uptake in bacteria. Besides several soluble subunits, the glucose-specific PTS includes the integral membrane protein IICB that couples the transmembrane transport of glucose to its phosphorylation. Here, we used electron crystallography of sugar-embedded tubular crystals of the glucose-specific IIC transport domain from Escherichia coli (ecIICglc) to visualize the structure of the transporter in the presence and absence of its substrate. Using an in vivo transport assay and binding competition experiments, we first established that, while it transports d-glucose, ecIICglc does not bind l-glucose. We then determined the projection structure of ecIICglc from tubular crystals embedded in d- and l-glucose and found a subtle conformational change. From comparison of the ecIICglc projection maps with crystal structures of other IIC transporters, we can deduce that the transporter adopts an inward-facing conformation, and that the maps in the presence and absence of the substrate reflect the transporter before and after release of the transported glucose into the cytoplasm. The transition associated with substrate release appears to require a subtle structural rearrangement in the region that includes hairpin 1.
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21
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Faghih-Mirzaee E, Dehestani M, Zeidabadinejad L. Computational study on transfer of L-ascorbic acid by UlaA through Escherichia coli membrane. J Bioinform Comput Biol 2017; 15:1750007. [PMID: 28335678 DOI: 10.1142/s021972001750007x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this study, the transfer of L-ascorbic acid by UlaA through Escherichia coli (E. coli) membrane was evaluated using density functional theory (DFT), molecular docking, and molecular dynamics (MD) simulation methods. DFT calculations at the B3lyp/6[Formula: see text]311[Formula: see text]G(p,d) level were performed to investigate the interaction properties and molecular descriptors. The physical properties, such as chemical potential, chemical hardness, and chemical electrophilicity of all studied molecules, were investigated. Natural population analysis was employed to describe the state of charge transfer between interactions using the natural bond orbital (NBO). The atoms in molecules (AIM) theory was used to examine the properties of the bond critical points such as their electron densities and Laplacians. Molecular docking studies showed that L-ascorbic acid was bounded to the internal cavity of UlaA. It was found that there were some hydrogen bond interactions between L-ascorbic acid and active sites of UlaA. The results of the MD simulation showed that the root mean square deviation (RMSD) of UlaA and L-ascorbic acid bound-UlaA reached equilibrium after 3.7[Formula: see text]ns. An evaluation of the radius of gyration ([Formula: see text]) revealed that UlaA and L-ascorbic acid bound-UlaA were stabilized around 10,000[Formula: see text]ns. Finally, analysis of the RMS fluctuations suggested that the structure of the L-ascorbic acid binding site remained approximately rigid during simulation. All obtained results shed light on the special manner of L-ascorbic acid transfer through E. coli membrane, and confirmed the results of previous studies on this issue.
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Affiliation(s)
- Ehsan Faghih-Mirzaee
- * Department of Medicinal Chemistry, Faculty of Pharmacy, Kerman University of Medical Sciences, Kerman, Iran.,† Pharmaceutics Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman 76175493, Iran
| | - Maryam Dehestani
- ‡ Department of Chemistry, Shahid Bahonar University of Kerman, Kerman, 76169-13,3 Iran
| | - Leila Zeidabadinejad
- ‡ Department of Chemistry, Shahid Bahonar University of Kerman, Kerman, 76169-13,3 Iran
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22
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The V-motifs facilitate the substrate capturing step of the PTS elevator mechanism. J Struct Biol 2016; 196:496-502. [PMID: 27720943 DOI: 10.1016/j.jsb.2016.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/02/2016] [Accepted: 10/05/2016] [Indexed: 12/17/2022]
Abstract
We propose that the alternative crystal forms of outward open UlaA (which are experimental, not simulated, and contain the substrate in the cavity) can be used to interpret/validate the MD results from MalT (the substrate capture step, which involves the mobile second TMSs of the V-motifs, TMSs 2 and 7). Since the crystal contacts are the same between the two alternative crystal forms of outward open UlaA, the striking biological differences noted, including rearranged hydrogen bonds and salt bridge coordination, are not attributable to crystal packing differences. Using transport assays, we identified G58 and G286 as essential for normal vitamin C transport, but the comparison of alternative crystal forms revealed that these residues to unhinge TMS movements from substrate-binding side chains, rendering the mid-TMS regions of homologous TMSs 2 and 7 relatively immobile. While the TMS that is involved in substrate binding in MalT is part of the homologous bundle that holds the two separate halves of the transport assembly (two proteins) together, an unequal effect of the two knockouts was observed for UlaA where both V-motifs are free from such dimer interface interactions.
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23
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McCoy JG, Ren Z, Stanevich V, Lee J, Mitra S, Levin EJ, Poget S, Quick M, Im W, Zhou M. The Structure of a Sugar Transporter of the Glucose EIIC Superfamily Provides Insight into the Elevator Mechanism of Membrane Transport. Structure 2016; 24:956-64. [PMID: 27161976 PMCID: PMC4899283 DOI: 10.1016/j.str.2016.04.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 04/09/2016] [Accepted: 04/14/2016] [Indexed: 01/07/2023]
Abstract
The phosphoenolpyruvate:carbohydrate phosphotransferase systems are found in bacteria, where they play central roles in sugar uptake and regulation of cellular uptake processes. Little is known about how the membrane-embedded components (EIICs) selectively mediate the passage of carbohydrates across the membrane. Here we report the functional characterization and 2.55-Å resolution structure of a maltose transporter, bcMalT, belonging to the glucose superfamily of EIIC transporters. bcMalT crystallized in an outward-facing occluded conformation, in contrast to the structure of another glucose superfamily EIIC, bcChbC, which crystallized in an inward-facing occluded conformation. The structures differ in the position of a structurally conserved substrate-binding domain that is suggested to play a central role in sugar transport. In addition, molecular dynamics simulations suggest a potential pathway for substrate entry from the periplasm into the bcMalT substrate-binding site. These results provide a mechanistic framework for understanding substrate recognition and translocation for the glucose superfamily EIIC transporters.
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Affiliation(s)
- Jason G. McCoy
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Zhenning Ren
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Vitali Stanevich
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Jumin Lee
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, KS 66047
| | - Sharmistha Mitra
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Elena J. Levin
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Sebastien Poget
- Department of Chemistry, College of Staten Island, Staten Island, NY 10314
| | - Matthias Quick
- Department of Psychiatry and Center for Molecular Recognition, Columbia University and New York State Psychiatric Institute, Division of Molecular Therapeutics, New York, New York 10032
| | - Wonpil Im
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, KS 66047
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
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24
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Transport protein evolution deduced from analysis of sequence, topology and structure. Curr Opin Struct Biol 2016; 38:9-17. [PMID: 27270239 DOI: 10.1016/j.sbi.2016.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 11/21/2022]
Abstract
The vast majority of well studied transmembrane channels, secondary carriers, primary active transporters and group translocators are believed to have arisen vis intragenic duplication events from simple channel-forming peptides with just 1-3 transmembrane α-helical segments, found ubiquitously in nature. Only a few established channel-forming proteins appear to have evolved via other pathways. The proposed pathway for the evolutionary appearance of the five types of transport proteins involved intragenic duplication of transmembrane pore-forming peptide-encoding genes, giving rise to channel proteins. These gave rise to single protein secondary carriers which upon superimposition of addition protein domains and proteins, including energy-coupling proteins and extracytoplasmic receptors, gave rise to multidomain, multicomponent carriers, primary active transporters and group translocators. Some of the largest and best characterized superfamilies of these transmembrane transport proteins are discussed from topological and evolutionary standpoints.
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25
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Affiliation(s)
- David Drew
- Centre for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
| | - Olga Boudker
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065;
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26
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Structure of eukaryotic purine/H(+) symporter UapA suggests a role for homodimerization in transport activity. Nat Commun 2016; 7:11336. [PMID: 27088252 PMCID: PMC4837479 DOI: 10.1038/ncomms11336] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 03/16/2016] [Indexed: 02/03/2023] Open
Abstract
The uric acid/xanthine H+ symporter, UapA, is a high-affinity purine transporter from the filamentous fungus Aspergillus nidulans. Here we present the crystal structure of a genetically stabilized version of UapA (UapA-G411VΔ1–11) in complex with xanthine. UapA is formed from two domains, a core domain and a gate domain, similar to the previously solved uracil transporter UraA, which belongs to the same family. The structure shows UapA in an inward-facing conformation with xanthine bound to residues in the core domain. Unlike UraA, which was observed to be a monomer, UapA forms a dimer in the crystals with dimer interactions formed exclusively through the gate domain. Analysis of dominant negative mutants is consistent with dimerization playing a key role in transport. We postulate that UapA uses an elevator transport mechanism likely to be shared with other structurally homologous transporters including anion exchangers and prestin. UapA is a uric acid/xanthine H+ symporter from a filamentous fungus. Here, the authors solve the crystal structure of the transporter in complex with xanthine revealing it to be a dimer, and this homodimerisation is proposed to be important for function.
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27
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Crystal structures reveal the molecular basis of ion translocation in sodium/proton antiporters. Nat Struct Mol Biol 2016; 23:248-55. [PMID: 26828964 DOI: 10.1038/nsmb.3164] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 12/30/2015] [Indexed: 11/09/2022]
Abstract
To fully understand the transport mechanism of Na(+)/H(+) exchangers, it is necessary to clearly establish the global rearrangements required to facilitate ion translocation. Currently, two different transport models have been proposed. Some reports have suggested that structural isomerization is achieved through large elevator-like rearrangements similar to those seen in the structurally unrelated sodium-coupled glutamate-transporter homolog GltPh. Others have proposed that only small domain movements are required for ion exchange, and a conventional rocking-bundle model has been proposed instead. Here, to resolve these differences, we report atomic-resolution structures of the same Na(+)/H(+) antiporter (NapA from Thermus thermophilus) in both outward- and inward-facing conformations. These data combined with cross-linking, molecular dynamics simulations and isothermal calorimetry suggest that Na(+)/H(+) antiporters provide alternating access to the ion-binding site by using elevator-like structural transitions.
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