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Chen G, Liang H, Zhao Q, Wu AM, Wang B. Exploiting MATE efflux proteins to improve flavonoid accumulation in Camellia sinensis in silico. Int J Biol Macromol 2019; 143:732-743. [PMID: 31622702 DOI: 10.1016/j.ijbiomac.2019.10.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 08/04/2019] [Accepted: 10/02/2019] [Indexed: 01/30/2023]
Abstract
Flavonoids in tea plant are the important bioactive compounds for both human health and taste quality. Multidrug and Toxic compound Extrusion (MATE) proteins could improve flavonoid accumulations by transporting and sequestering the flavonoid in vacuoles. We identified 41 putative MATE genes in tea plants. The similar intron-exon structures of tea MATEs clustered within the same gene clade. The correlation analysis of tea flavonoid and transcriptome data showed that TEA006173 might be involve in the tea flavonoid accumulation. The RT-PCR results confirmed that TEA006173 showed high expression in the young leaf tissues. Tertiary structure prediction has shown that TEA006173 contained the 12 helices with three active pockets, comprising 13 critical residues. The present study provided the structural variations and expression patterns of tea MATEs and it would be helpful for taste and nutrient quality improvement in tea plant.
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Affiliation(s)
- Guanming Chen
- The Key Laboratory of Plant Molecular Breeding of Guangdong Province, College of Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Haohong Liang
- The Key Laboratory of Plant Molecular Breeding of Guangdong Province, College of Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Qi Zhao
- The Key Laboratory of Plant Molecular Breeding of Guangdong Province, College of Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Ai-Min Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou 510642, China; Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University, Guangzhou 510642, China
| | - Bo Wang
- The Key Laboratory of Plant Molecular Breeding of Guangdong Province, College of Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China.
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52
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Dey D, Siddiqui SI, Mamidi P, Ghosh S, Kumar CS, Chattopadhyay S, Ghosh S, Banerjee M. The effect of amantadine on an ion channel protein from Chikungunya virus. PLoS Negl Trop Dis 2019; 13:e0007548. [PMID: 31339886 PMCID: PMC6655611 DOI: 10.1371/journal.pntd.0007548] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 06/11/2019] [Indexed: 01/01/2023] Open
Abstract
Viroporins like influenza A virus M2, hepatitis C virus p7, HIV-1 Vpu and picornavirus 2B associate with host membranes, and create hydrophilic corridors, which are critical for viral entry, replication and egress. The 6K proteins from alphaviruses are conjectured to be viroporins, essential during egress of progeny viruses from host membranes, although the analogue in Chikungunya Virus (CHIKV) remains relatively uncharacterized. Using a combination of electrophysiology, confocal and electron microscopy, and molecular dynamics simulations we show for the first time that CHIKV 6K is an ion channel forming protein that primarily associates with endoplasmic reticulum (ER) membranes. The ion channel activity of 6K can be inhibited by amantadine, an antiviral developed against the M2 protein of Influenza A virus; and CHIKV infection of cultured cells can be effectively inhibited in presence of this drug. Our study provides crucial mechanistic insights into the functionality of 6K during CHIKV-host interaction and suggests that 6K is a potential therapeutic drug target, with amantadine and its derivatives being strong candidates for further development. Chikungunya fever is a severe crippling illness caused by the arthropod-borne virus CHIKV. Originally from the African subcontinent, the virus has now spread worldwide and is responsible for substantial morbidity and economic loss. The existing treatment against CHIKV is primarily symptomatic, and it is imperative that specific therapeutics be devised. The present study provides detailed insight into the functionality of 6K, an ion channel forming protein of CHIKV. Amantadine, a known antiviral against influenza virus, also inhibits CHIKV replication in cell culture and drastically alters the morphology of virus particles. This work highlights striking parallels among functionalities of virus-encoded membrane-interacting proteins, which may be exploited for developing broad-spectrum antivirals.
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Affiliation(s)
- Debajit Dey
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, India
| | | | | | - Sukanya Ghosh
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, India
| | | | | | - Subhendu Ghosh
- Department of Biophysics, University of Delhi (South Campus), Delhi, India
| | - Manidipa Banerjee
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, India
- * E-mail:
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53
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Suresh A, Hung A. Structural effects of divalent calcium cations on the α7 nicotinic acetylcholine receptor: A molecular dynamics simulation study. Proteins 2019; 87:992-1005. [PMID: 31228282 DOI: 10.1002/prot.25761] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 05/27/2019] [Accepted: 06/15/2019] [Indexed: 12/11/2022]
Abstract
The α7 subtype of neuronal nicotinic acetylcholine receptor (nAChR) is a ligand-gated ion channel protein that is vital to various neurological functions, including modulation of neurotransmitter release. A relatively high concentration of extracellular Ca2+ in the neuronal environment is likely to exert substantial structural and functional influence on nAChRs, which may affect their interactions with agonists and antagonists. In this work, we employed atomistic molecular dynamics (MD) simulations to examine the effects of elevated Ca2+ on the structure and dynamics of α7 nAChR embedded in a model phospholipid bilayer. Our results suggest that the presence of Ca2+ in the α7 nAChR environment results in closure of loop C-in the extracellular ligand-binding domain, a motion normally associated with agonist binding and receptor activation. Elevated Ca2+ also alters the conformation of key regions of the receptor, including the inter-helical loops, pore-lining helices and the "gate" residues, and causes partial channel opening in the absence of an agonist, leading to an attendant reduction in the free energy of Ca2+ permeation through the pore as elucidated by umbrella sampling simulations. Overall, the structural and permeability changes in α7 nAChR suggest that elevated Ca2+ induces a partially activated receptor state that is distinct from both the resting and the agonist-activated states. These results are consistent with the notion that divalent ions can serve as a potentiator of nAChRs, resulting in a higher rate of receptor activation (and subsequent desensitization) in the presence of agonists, with possible implications for diseases involving calcium dysregulation.
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Affiliation(s)
- Abishek Suresh
- School of Science, RMIT University, Melbourne, Victoria, Australia
| | - Andrew Hung
- School of Science, RMIT University, Melbourne, Victoria, Australia
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54
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Shivaraj SM, Deshmukh R, Sonah H, Bélanger RR. Identification and characterization of aquaporin genes in Arachis duranensis and Arachis ipaensis genomes, the diploid progenitors of peanut. BMC Genomics 2019; 20:222. [PMID: 30885116 PMCID: PMC6423786 DOI: 10.1186/s12864-019-5606-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/13/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Aquaporins (AQPs) facilitate transport of water and small solutes across cell membranes and play an important role in different physiological processes in plants. Despite their importance, limited data is available about AQP distribution and function in the economically important oilseed crop peanut, Arachis hypogea (AABB). The present study reports the identification and structural and expression analysis of the AQPs found in the diploid progenitor genomes of A. hypogea i.e. Arachis duranensis (AA) and Arachis ipaensis (BB). RESULTS Genome-wide analysis revealed the presence of 32 and 36 AQPs in A. duranensis and A. ipaensis, respectively. Phylogenetic analysis showed similar numbers of AQPs clustered in five distinct subfamilies including the plasma membrane intrinsic proteins (PIPs), the tonoplast intrinsic proteins (TIPs), the nodulin 26-like intrinsic proteins (NIPs), the small basic intrinsic proteins (SIPs), and the uncharacterized intrinsic proteins (XIPs). A notable exception was the XIP subfamily where XIP1 group was observed only in A. ipaensis genome. Protein structure evaluation showed a hydrophilic aromatic/arginine (ar/R) selectivity filter (SF) in PIPs whereas other subfamilies mostly contained a hydrophobic ar/R SF. Both genomes contained one NIP2 with a GSGR SF indicating a conserved ability within the genus to uptake silicon. Analysis of RNA-seq data from A. hypogea revealed a similar expression pattern for the different AQP paralogs of AA and BB genomes. The TIP3s showed seed-specific expression while the NIP1s' expression was confined to roots and root nodules. CONCLUSIONS The identification and the phylogenetic analysis of AQPs in both Arachis species revealed the presence of all five sub-families of AQPs. Within the NIP subfamily, the presence of a NIP2 in both genomes supports a conserved ability to absorb Si within plants of the genus. The global expression profile of AQPs in A. hypogea revealed a similar pattern of AQP expression regardless of the subfamilies or the genomes. The tissue-specific expression of AQPs suggests an important role in the development and function of the respective organs. The AQPs identified in the present study will serve as a resource for further characterization and possible exploitation of AQPs to understand their physiological role in A. hypogea.
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Affiliation(s)
- S. M. Shivaraj
- Département de phytologie–Faculté des Sciences de l’agriculture et de l’alimentation, Université Laval, 2425 rue de l’Agriculture, Québec City, QC G1V 0A6 Canada
| | - Rupesh Deshmukh
- National Agri-Food Biotechnology Institute (NABI), Mohali, India
| | - Humira Sonah
- National Agri-Food Biotechnology Institute (NABI), Mohali, India
| | - Richard R. Bélanger
- Département de phytologie–Faculté des Sciences de l’agriculture et de l’alimentation, Université Laval, 2425 rue de l’Agriculture, Québec City, QC G1V 0A6 Canada
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55
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Roles of the Hydrophobic Gate and Exit Channel in Vigna radiata Pyrophosphatase Ion Translocation. J Mol Biol 2019; 431:1619-1632. [PMID: 30878480 DOI: 10.1016/j.jmb.2019.03.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/26/2019] [Accepted: 03/03/2019] [Indexed: 12/25/2022]
Abstract
Membrane-embedded pyrophosphatase (M-PPase) hydrolyzes pyrophosphate to drive ion (H+ and/or Na+) translocation. We determined crystal structures and functions of Vigna radiata M-PPase (VrH+-PPase), the VrH+-PPase-2Pi complex and mutants at hydrophobic gate (residue L555) and exit channel (residues T228 and E225). Ion pore diameters along the translocation pathway of three VrH+-PPases complexes (Pi-, 2Pi- and imidodiphosphate-bound states) present a unique wave-like profile, with different pore diameters at the hydrophobic gate and exit channel, indicating that the ligands induced pore size alterations. The 2Pi-bound state with the largest pore diameter might mimic the hydrophobic gate open. In mutant structures, ordered waters detected at the hydrophobic gate among VrH+-PPase imply the possibility of solvation, and numerous waters at the exit channel might signify an open channel. A salt-bridge, E225-R562 is at the way out of the exit channel of VrH+-PPase; E225A mutant makes the interaction eliminated and reveals a decreased pumping ability. E225-R562 might act as a latch to regulate proton release. A water wire from the ion gate (R-D-K-E) through the hydrophobic gate and into the exit channel may reflect the path of proton transfer.
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56
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Sequence and structural analysis of OmpW protein of Pasteurella multocida strains reveal evolutionary conservation among members of Pasteurellaceae along with its homologues. GENE REPORTS 2019. [DOI: 10.1016/j.genrep.2018.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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57
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Khan S, Thomas BR, de la Mata R, Randall MJ, Zhang W, Zwiazek JJ. Variation in Aquaporin and Physiological Responses Among Pinus contorta Families Under Different Moisture Conditions. PLANTS 2019; 8:plants8010013. [PMID: 30621354 PMCID: PMC6359517 DOI: 10.3390/plants8010013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/22/2018] [Accepted: 12/31/2018] [Indexed: 01/05/2023]
Abstract
A population of eight open pollinated families of Pinus contorta was selected from sites varying in precipitation regimes and elevation to examine the possible role of aquaporins in adaptation to different moisture conditions. Five Pinus contorta aquaporins encoding PiconPIP2;1, PiconPIP2;2, PiconPIP2;3, PiconPIP1;2, and PiconTIP1;1 were cloned and detailed structural analyses were conducted to provide essential information that can explain their biological and molecular function. All five PiconAQPs contained hydrophilic aromatic/arginine selective filters to facilitate the transport of water. Transcript abundance patterns of PiconAQPs varied significantly across the P. contorta families under varying soil moisture conditions. The transcript abundance of five PiconPIPs remained unchanged under control and water-stress conditions in two families that originated from the sites with lower precipitation levels. These two families also displayed a different adaptive strategy of photosynthesis to cope with drought stress, which was manifested by reduced sensitivity in photosynthesis (maintaining the same rate) while exhibiting a reduction in stomatal conductance. In general, root:shoot ratios were not affected by drought stress, but some variation was observed between families. The results showed variability in drought coping mechanisms, including the expression of aquaporin genes and plant biomass allocation among eight families of Pinus contorta.
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Affiliation(s)
- Shanjida Khan
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Bldg., Edmonton, AB T6G 2E3, Canada.
| | - Barb R Thomas
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Bldg., Edmonton, AB T6G 2E3, Canada.
| | - Raul de la Mata
- Institut de Recerca i Tecnología Agroalimentàries (IRTA), Torre Marimon, 08140 Caldes de Montbui, Spain.
| | - Morgan J Randall
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Bldg., Edmonton, AB T6G 2E3, Canada.
| | - Wenqing Zhang
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Bldg., Edmonton, AB T6G 2E3, Canada.
| | - Janusz J Zwiazek
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Bldg., Edmonton, AB T6G 2E3, Canada.
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58
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Tejada MG, Sudhakar S, Kim NK, Aoyama H, Shilton BH, Bai D. Variants with increased negative electrostatic potential in the Cx50 gap junction pore increased unitary channel conductance and magnesium modulation. Biochem J 2018; 475:3315-3330. [PMID: 30287491 DOI: 10.1042/bcj20180523] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 10/03/2018] [Accepted: 10/04/2018] [Indexed: 11/17/2022]
Abstract
Gap junction (GJ) channels are oligomers of connexins forming channels linking neighboring cells. GJs formed by different connexins show distinct unitary channel conductance (γj), transjunctional voltage-dependent gating (Vj-gating) properties, and modulation by intracellular magnesium ([Mg2+]i). The underlying molecular determinants are not fully clear. Previous experimental evidence indicates that residues in the amino terminal (NT) and initial segment of the first extracellular (E1) domain influence the γj, Vj-gating, and/or [Mg2+]i modulation in several GJs. Increasing negatively charged residues in Cx50 (connexin50) E1 (G46D or G46E) increased γj, while increasing positively charged residue (G46K) reduced the γj Sequence alignment of Cx50 and Cx37 in the NT and E1 domains revealed that in Cx50 G8 and V53, positions are negatively charged residues in Cx37 (E8 and E53, respectively). To evaluate these residues together, we generated a triple variant in Cx50, G8E, G46E, and V53E simultaneously to study its γj, Vj-gating properties, and modulation by [Mg2+]i Our data indicate that the triple variant and individual variants G8E, G46E, and V53E significantly increased Cx50 GJ γj without a significant change in the Vj gating. In addition, elevated [Mg2+]i reduced γj in Cx50 and all the variant GJs. These results and our homology structural models suggest that these NT/E1 residues are likely to be pore-lining and the variants increased the negative electrostatic potentials along the GJ pore to facilitate the γj of this cation-preferring GJ channel. Our results indicate that electrostatic properties of the Cx50 GJ pore are important for the γj and the [Mg2+]i modulation.
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Affiliation(s)
- Mary Grace Tejada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Swathy Sudhakar
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Nicholas K Kim
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Hiroshi Aoyama
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Brian H Shilton
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
| | - Donglin Bai
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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59
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Noori HR, Mücksch C, Vengeliene V, Schönig K, Takahashi TT, Mukhtasimova N, Bagher Oskouei M, Mosqueira M, Bartsch D, Fink R, Urbassek HM, Spanagel R, Sine SM. Alcohol reduces muscle fatigue through atomistic interactions with nicotinic receptors. Commun Biol 2018; 1:159. [PMID: 30302403 PMCID: PMC6170420 DOI: 10.1038/s42003-018-0157-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 08/21/2018] [Indexed: 11/08/2022] Open
Abstract
Alcohol consumption affects many organs and tissues, including skeletal muscle. However, the molecular mechanism of ethanol action on skeletal muscle remains unclear. Here, using molecular dynamics simulations and single channel recordings, we show that ethanol interacts with a negatively charged amino acid within an extracellular region of the neuromuscular nicotinic acetylcholine receptor (nAChR), thereby altering its global conformation and reducing the single channel current amplitude. Charge reversal of the negatively charged amino acid abolishes the nAChR-ethanol interaction. Moreover, using transgenic animals harboring the charge-reversal mutation, ex vivo measurements of muscle force production show that ethanol counters fatigue in wild type but not homozygous αE83K mutant animals. In accord, in vivo studies of motor coordination following ethanol administration reveal an approximately twofold improvement for wild type compared to homozygous mutant animals. Together, the converging results from molecular to animal studies suggest that ethanol counters muscle fatigue through its interaction with neuromuscular nAChRs.
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Affiliation(s)
- Hamid R Noori
- Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5, 68159, Mannheim, Germany.
- Neuronal Convergence Group, Max Planck Institute for Biological Cybernetics, Max Panck Ring 8, 72076, Tübingen, Germany.
- Physics Department and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger Strasse 46, 67663, Kaiserslautern, Germany.
- Courant Institute for Mathematical Sciences, New York University, 251 Mercer Street, New York, NY, 10012, USA.
- Neuronal Convergence Group, Max Planck Institute for Biological Cybernetics, Max Planck Ring 8, 72076, Tübingen, Germany.
| | - Christian Mücksch
- Physics Department and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger Strasse 46, 67663, Kaiserslautern, Germany
| | - Valentina Vengeliene
- Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5, 68159, Mannheim, Germany
| | - Kai Schönig
- Department of Molecular Biology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5, 68159, Mannheim, Germany
| | - Tatiane T Takahashi
- Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5, 68159, Mannheim, Germany
| | - Nuriya Mukhtasimova
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN, 55905, USA
| | - Maryam Bagher Oskouei
- Neuronal Convergence Group, Max Planck Institute for Biological Cybernetics, Max Panck Ring 8, 72076, Tübingen, Germany
| | - Matias Mosqueira
- Institute of Physiology and Pathophysiology, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
| | - Dusan Bartsch
- Department of Molecular Biology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5, 68159, Mannheim, Germany
| | - Rainer Fink
- Institute of Physiology and Pathophysiology, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
| | - Herbert M Urbassek
- Physics Department and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger Strasse 46, 67663, Kaiserslautern, Germany
| | - Rainer Spanagel
- Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5, 68159, Mannheim, Germany
| | - Steven M Sine
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN, 55905, USA
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60
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An Algorithm for Computing Side Chain Conformational Variations of a Protein Tunnel/Channel. Molecules 2018; 23:molecules23102459. [PMID: 30261587 PMCID: PMC6222877 DOI: 10.3390/molecules23102459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 09/21/2018] [Accepted: 09/22/2018] [Indexed: 11/16/2022] Open
Abstract
In this paper, a novel method to compute side chain conformational variations for a protein molecule tunnel (or channel) is proposed. From the conformational variations, we compute the flexibly deformed shapes of the initial tunnel, and present a way to compute the maximum size of the ligand that can pass through the deformed tunnel. By using the two types of graphs corresponding to amino acids and their side chain rotamers, the suggested algorithm classifies amino acids and rotamers which possibly have collisions. Based on the divide and conquer technique, local side chain conformations are computed first, and then a global conformation is generated by combining them. With the exception of certain cases, experimental results show that the algorithm finds up to 327,680 valid side chain conformations from 128~1233 conformation candidates within three seconds.
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61
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Mapping the sensing spots of aerolysin for single oligonucleotides analysis. Nat Commun 2018; 9:2823. [PMID: 30026547 PMCID: PMC6053387 DOI: 10.1038/s41467-018-05108-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 06/05/2018] [Indexed: 12/05/2022] Open
Abstract
Nanopore sensing is a powerful single-molecule method for DNA and protein sequencing. Recent studies have demonstrated that aerolysin exhibits a high sensitivity for single-molecule detection. However, the lack of the atomic resolution structure of aerolysin pore has hindered the understanding of its sensing capabilities. Herein, we integrate nanopore experimental results and molecular simulations based on a recent pore structural model to precisely map the sensing spots of this toxin for ssDNA translocation. Rationally probing ssDNA length and composition upon pore translocation provides new important insights for molecular determinants of the aerolysin nanopore. Computational and experimental results reveal two critical sensing spots (R220, K238) generating two constriction points along the pore lumen. Taking advantage of the sensing spots, all four nucleobases, cytosine methylation and oxidation of guanine can be clearly identified in a mixture sample. The results provide evidence for the potential of aerolysin as a nanosensor for DNA sequencing. Nanopores are an emerging powerful single-molecule method of DNA sequencing. Here the authors map the structure of aerolysin for use as a nanopore and show detection of modified and unmodified nucleobases.
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62
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Assur Sanghai Z, Liu Q, Clarke OB, Belcher-Dufrisne M, Wiriyasermkul P, Giese MH, Leal-Pinto E, Kloss B, Tabuso S, Love J, Punta M, Banerjee S, Rajashankar KR, Rost B, Logothetis D, Quick M, Hendrickson WA, Mancia F. Structure-based analysis of CysZ-mediated cellular uptake of sulfate. eLife 2018; 7:27829. [PMID: 29792261 PMCID: PMC5967866 DOI: 10.7554/elife.27829] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 04/11/2018] [Indexed: 01/25/2023] Open
Abstract
Sulfur, most abundantly found in the environment as sulfate (SO42-), is an essential element in metabolites required by all living cells, including amino acids, co-factors and vitamins. However, current understanding of the cellular delivery of SO42- at the molecular level is limited. CysZ has been described as a SO42- permease, but its sequence family is without known structural precedent. Based on crystallographic structure information, SO42- binding and flux experiments, we provide insight into the molecular mechanism of CysZ-mediated translocation of SO42- across membranes. CysZ structures from three different bacterial species display a hitherto unknown fold and have subunits organized with inverted transmembrane topology. CysZ from Pseudomonas denitrificans assembles as a trimer of antiparallel dimers and the CysZ structures from two other species recapitulate dimers from this assembly. Mutational studies highlight the functional relevance of conserved CysZ residues.
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Affiliation(s)
- Zahra Assur Sanghai
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States
| | - Qun Liu
- Biology Department, Brookhaven National Laboratory, Upton, United States
| | - Oliver B Clarke
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States
| | - Meagan Belcher-Dufrisne
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States
| | - Pattama Wiriyasermkul
- Center for Molecular Recognition, Department of Psychiatry, Columbia University, New York, United States
| | - M Hunter Giese
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States
| | - Edgar Leal-Pinto
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, United States.,Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, United States
| | - Brian Kloss
- New York Structural Biology Center, New York, United States
| | | | - James Love
- New York Structural Biology Center, New York, United States
| | - Marco Punta
- Centre for Evolution and Cancer, The Institute of Cancer Research, London, United Kingdom
| | - Surajit Banerjee
- Department of Chemistry and Chemical Biology, Cornell University, NE-CAT, Argonne, United States
| | | | - Burkhard Rost
- Department of Informatics, Technical University of Munich, Munich, Germany
| | - Diomedes Logothetis
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, United States.,Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, United States
| | - Matthias Quick
- Center for Molecular Recognition, Department of Psychiatry, Columbia University, New York, United States.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, United States
| | - Wayne A Hendrickson
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States.,New York Structural Biology Center, New York, United States
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States
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63
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Oversized galactosides as a probe for conformational dynamics in LacY. Proc Natl Acad Sci U S A 2018; 115:4146-4151. [PMID: 29602806 DOI: 10.1073/pnas.1800706115] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Binding kinetics of α-galactopyranoside homologs with fluorescent aglycones of different sizes and shapes were determined with the lactose permease (LacY) of Escherichia coli by FRET from Trp151 in the binding site of LacY to the fluorophores. Fast binding was observed with LacY stabilized in an outward-open conformation (kon = 4-20 μM-1·s-1), indicating unobstructed access to the binding site even for ligands that are much larger than lactose. Dissociation rate constants (koff) increase with the size of the aglycone so that Kd values also increase but remain in the micromolar range for each homolog. Phe27 (helix I) forms an apparent constriction in the pathway for sugar by protruding into the periplasmic cavity. However, replacement of Phe27 with a bulkier Trp does not create an obstacle in the pathway even for large ligands, since binding kinetics remain unchanged. High accessibility of the binding site is also observed in a LacY/nanobody complex with partially blocked periplasmic opening. Remarkably, E. coli expressing WT LacY catalyzes transport of α- or β-galactopyranosides with oversized aglycones such as bodipy or Aldol518, which may require an extra space within the occluded intermediate. The results confirm that LacY specificity is strictly directed toward the galactopyranoside ring and also clearly indicate that the opening on the periplasmic side is sufficiently wide to accommodate the large galactoside derivatives tested here. We conclude that the actual pathway for the substrate entering from the periplasmic side is wider than the pore diameter calculated in the periplasmic-open X-ray structures.
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64
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Lee GY, You DG, Lee HR, Hwang SW, Lee CJ, Yoo YD. Romo1 is a mitochondrial nonselective cation channel with viroporin-like characteristics. J Cell Biol 2018; 217:2059-2071. [PMID: 29545371 PMCID: PMC5987721 DOI: 10.1083/jcb.201709001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 01/22/2018] [Accepted: 02/28/2018] [Indexed: 11/22/2022] Open
Abstract
Romo1 regulates mitochondrial reactive oxygen species production and acts as an essential redox sensor in mitochondrial dynamics. Lee et al. demonstrate that Romo1 is a unique mitochondrial ion channel with viroporin-like characteristics that distinguish Romo1 from other known eukaryotic ion channels. Reactive oxygen species (ROS) modulator 1 (Romo1) is a nuclear-encoded mitochondrial inner membrane protein known to regulate mitochondrial ROS production and to act as an essential redox sensor in mitochondrial dynamics. Although its physiological roles have been studied for a decade, the biophysical mechanisms that explain these activities of Romo1 are unclear. In this study, we report that Romo1 is a unique mitochondrial ion channel that differs from currently identified eukaryotic ion channels. Romo1 is a highly conserved protein with structural features of class II viroporins, which are virus-encoded nonselective cation channels. Indeed, Romo1 forms a nonselective cation channel with its amphipathic helical transmembrane domain necessary for pore-forming activity. Notably, channel activity was specifically inhibited by Fe2+ ions, an essential transition metal ion in ROS metabolism. Using structural bioinformatics, we designed an experimental data–guided structural model of Romo1 with a rational hexameric structure. We propose that Romo1 establishes a new category of viroporin-like nonselective cation channel in eukaryotes.
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Affiliation(s)
- Gi Young Lee
- Laboratory of Molecular Cell Biology, Graduate School of Medicine, Korea University College of Medicine, Korea University, Seoul, Republic of Korea
| | - Deok-Gyun You
- Laboratory of Molecular Cell Biology, Graduate School of Medicine, Korea University College of Medicine, Korea University, Seoul, Republic of Korea
| | - Hye-Ra Lee
- Laboratory of Molecular Cell Biology, Graduate School of Medicine, Korea University College of Medicine, Korea University, Seoul, Republic of Korea.,Department of Biosystems and Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Sun Wook Hwang
- Department of Biomedical Sciences, Korea University College of Medicine, Korea University, Seoul, Republic of Korea
| | - C Justin Lee
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology, Seoul, Republic of Korea.,Korea University-Korea Institute of Science and Technology Graduate School of Convergence Technology, Korea University, Seoul, Republic of Korea
| | - Young Do Yoo
- Laboratory of Molecular Cell Biology, Graduate School of Medicine, Korea University College of Medicine, Korea University, Seoul, Republic of Korea
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Streptomyces spp. in the biocatalysis toolbox. Appl Microbiol Biotechnol 2018; 102:3513-3536. [PMID: 29502181 DOI: 10.1007/s00253-018-8884-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 02/17/2018] [Accepted: 02/19/2018] [Indexed: 02/07/2023]
Abstract
About 20,100 research publications dated 2000-2017 were recovered searching the PubMed and Web of Science databases for Streptomyces, which are the richest known source of bioactive molecules. However, these bacteria with versatile metabolism are powerful suppliers of biocatalytic tools (enzymes) for advanced biotechnological applications such as green chemical transformations and biopharmaceutical and biofuel production. The recent technological advances, especially in DNA sequencing coupled with computational tools for protein functional and structural prediction, and the improved access to microbial diversity enabled the easier access to enzymes and the ability to engineer them to suit a wider range of biotechnological processes. The major driver behind a dramatic increase in the utilization of biocatalysis is sustainable development and the shift toward bioeconomy that will, in accordance to the UN policy agenda "Bioeconomy to 2030," become a global effort in the near future. Streptomyces spp. already play a significant role among industrial microorganisms. The intention of this minireview is to highlight the presence of Streptomyces in the toolbox of biocatalysis and to give an overview of the most important advances in novel biocatalyst discovery and applications. Judging by the steady increase in a number of recent references (228 for the 2000-2017 period), it is clear that biocatalysts from Streptomyces spp. hold promises in terms of valuable properties and applicative industrial potential.
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66
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Benkerrou D, Ceccarelli M. Free energy calculations and molecular properties of substrate translocation through OccAB porins. Phys Chem Chem Phys 2018. [DOI: 10.1039/c7cp08299a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We investigated with molecular modeling the translocation of simple substrates through four similar specific bacterial porins from the Acinetobacter baumannii pathogen providing structure–function analysis at the molecular level.
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67
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Newcombe J, Chatzidaki A, Sheppard TD, Topf M, Millar NS. Diversity of Nicotinic Acetylcholine Receptor Positive Allosteric Modulators Revealed by Mutagenesis and a Revised Structural Model. Mol Pharmacol 2017; 93:128-140. [PMID: 29196491 PMCID: PMC5767682 DOI: 10.1124/mol.117.110551] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/30/2017] [Indexed: 01/26/2023] Open
Abstract
By combining electrophysiological and computational approaches we have examined a series of positive allosteric modulators (PAMs) acting on the human α7 nicotinic acetylcholine receptor (nAChR). Electrophysiological studies have focused on three α7-selective PAMs (A-867744, TBS-516, and TQS) that display similar effects on wild-type α7 nAChRs. In addition to potentiating agonist-evoked responses, all three compounds reduce receptor desensitization and, consequently, are classed as type II PAMs. Despite having similar effects on wild-type receptors, A-867744 was found to have profoundly differing effects on mutated receptors compared with TBS-516 and TQS, a finding that is consistent with previous studies indicating that A-867744 may have a different mechanism of action compare with other α7-selective type II PAMs. Due to evidence that these PAMs bind within the α7 nAChR transmembrane region, we generated and validated new structural models of α7. Importantly, we have corrected a previously identified error in the transmembrane region of the original cryo–electron microscopy Torpedo model; the only pentameric ligand-gated ion channel imaged in a native lipid membrane. Real-space refinement was used to generate closed and open conformations on which the α7 models were based. Consensus docking with an extended series of PAMs with chemical similarity to A-867744, TBS-516, and TQS suggests that all bind to a broadly similar intersubunit transmembrane site. However, differences in the predicted binding of A-867744, compared with TBS-516 and TQS, may help to explain the distinct functional effects of A-867744. Thus, our revised structural models may provide a useful tool for interpreting functional effects of PAMs.
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Affiliation(s)
- Joseph Newcombe
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
| | - Anna Chatzidaki
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
| | - Tom D Sheppard
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
| | - Maya Topf
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
| | - Neil S Millar
- Departments of Chemistry (J.N., T.D.S.) and Neuroscience, Physiology and Pharmacology (A.C., N.S.M.), University College London, London, United Kingdom; and Institute of Structural and Molecular Biology, Birkbeck, University of London, London, United Kingdom (J.N., M.T.)
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Simões T, Lopes D, Dias S, Fernandes F, Pereira J, Jorge J, Bajaj C, Gomes A. Geometric Detection Algorithms for Cavities on Protein Surfaces in Molecular Graphics: A Survey. COMPUTER GRAPHICS FORUM : JOURNAL OF THE EUROPEAN ASSOCIATION FOR COMPUTER GRAPHICS 2017; 36:643-683. [PMID: 29520122 PMCID: PMC5839519 DOI: 10.1111/cgf.13158] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Detecting and analyzing protein cavities provides significant information about active sites for biological processes (e.g., protein-protein or protein-ligand binding) in molecular graphics and modeling. Using the three-dimensional structure of a given protein (i.e., atom types and their locations in 3D) as retrieved from a PDB (Protein Data Bank) file, it is now computationally viable to determine a description of these cavities. Such cavities correspond to pockets, clefts, invaginations, voids, tunnels, channels, and grooves on the surface of a given protein. In this work, we survey the literature on protein cavity computation and classify algorithmic approaches into three categories: evolution-based, energy-based, and geometry-based. Our survey focuses on geometric algorithms, whose taxonomy is extended to include not only sphere-, grid-, and tessellation-based methods, but also surface-based, hybrid geometric, consensus, and time-varying methods. Finally, we detail those techniques that have been customized for GPU (Graphics Processing Unit) computing.
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Affiliation(s)
- Tiago Simões
- Instituto de Telecomunicações, Portugal
- Universidade da Beira Interior, Portugal
| | | | - Sérgio Dias
- Instituto de Telecomunicações, Portugal
- Universidade da Beira Interior, Portugal
| | | | - João Pereira
- INESC-ID Lisboa, Portugal
- Instituto Superior Técnico, Universidade de Lisboa, Portugal
| | - Joaquim Jorge
- INESC-ID Lisboa, Portugal
- Instituto Superior Técnico, Universidade de Lisboa, Portugal
| | | | - Abel Gomes
- Instituto de Telecomunicações, Portugal
- Universidade da Beira Interior, Portugal
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69
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Prediction of arsenic and antimony transporter major intrinsic proteins from the genomes of crop plants. Int J Biol Macromol 2017; 107:2630-2642. [PMID: 29080824 DOI: 10.1016/j.ijbiomac.2017.10.153] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 10/24/2017] [Accepted: 10/24/2017] [Indexed: 01/17/2023]
Abstract
Major intrinsic proteins (MIPs), commonly known as aquaporins, transport water and non-polar small solutes. Comparing the 3D models and the primary selectivity-related motifs (two Asn-Pro-Ala (NPA) regions, the aromatic/arginine (ar/R) selectivity filter, and Froger's positions (FPs)) of all plant MIPs that have been experimentally proven to transport arsenic (As) and antimony (Sb), some substrate-specific signature sequences (SSSS) or specificity determining sites (SDPs) have been predicted. These SSSS or SDPs were determined in 543 MIPs found in the genomes of 12 crop plants; the As and Sb transporters were predicted to be distributed in noduline-26 like intrinsic proteins (NIPs), and every plant had one or several As and Sb transporter NIPs. Phylogenetic grouping of the NIP subfamily based on the ar/R selectivity filter and FPs were linked to As and Sb transport. We further determined the group-wise substrate selectivity profiles of the NIPs in the 12 crop plants. In addition to two NPA regions, the ar/R filter, and FPs, certain amino acids especially in the pore line, loop D, and termini contribute to the functional distinctiveness of the NIP groups. Expression analysis of transcripts in different organs indicated that most of the As and Sb transporter NIPs were expressed in roots.
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70
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Venom-derived peptides inhibiting Kir channels: Past, present, and future. Neuropharmacology 2017; 127:161-172. [PMID: 28716449 DOI: 10.1016/j.neuropharm.2017.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/05/2017] [Accepted: 07/13/2017] [Indexed: 12/17/2022]
Abstract
Inwardly rectifying K+ (Kir) channels play a significant role in vertebrate and invertebrate biology by regulating the movement of K+ ions involved in membrane transport and excitability. Yet unlike other ion channels including their ancestral K+-selective homologs, there are very few venom toxins known to target and inhibit Kir channels with the potency and selectivity found for the Ca2+-activated and voltage-gated K+ channel families. It is unclear whether this is simply due to a lack of discovery, or instead a consequence of the evolutionary processes that drive the development of venom components towards their targets based on a collective efficacy to 1) elicit pain for defensive purposes, 2) promote paralysis for prey capture, or 3) facilitate delivery of venom components into the circulation. The past two decades of venom screening has yielded three venom peptides with inhibitory activity towards mammalian Kir channels, including the discovery of tertiapin, a high-affinity pore blocker from the venom of the European honey bee Apis mellifera. Venomics and structure-based computational approaches represent exciting new frontiers for venom peptide development, where re-engineering peptide 'scaffolds' such as tertiapin may aid in the quest to expand the palette of potent and selective Kir channel blockers for future research and potentially new therapeutics. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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71
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Vollan HS, Tannæs T, Caugant DA, Vriend G, Bukholm G. Outer membrane phospholipase A's roles in Helicobacter pylori acid adaptation. Gut Pathog 2017; 9:36. [PMID: 28616083 PMCID: PMC5469174 DOI: 10.1186/s13099-017-0184-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 06/08/2017] [Indexed: 02/08/2023] Open
Abstract
Background The pH of the human gastric mucosa varies around 2.5 so that only bacteria with strong acidic stress tolerance can colonize it. The ulcer causing Helicobacter pylori thrives in the gastric mucosa. We analyse the roles of the key outer membrane protein OMPLA in its roles in acid tolerance. Results The homology model of Helicobacter pylori outer membrane phospholipase A (OMPLA) reveals a twelve stranded β-barrel with a pore that allows molecules to pass with a diameter up to 4 Å. Structure based multiple sequence alignments revealed the functional roles of many amino acids, and led to the suggestion that OMPLA has multiple functions. Besides its role as phospholipase it lets urea enter and ammonium exit the periplasm. Combined with an extensive literature study, our work leads to a comprehensive model for H. pylori’s acid tolerance. This model is based on the conversion of urea into ammonium, and it includes multiple roles for OMPLA and involves two hitherto little studied membrane channels in the OMPLA operon. Conclusion The three-dimensional model of OMPLA predicts a transmembrane pore that can aid H. pylori’s acid tolerance through urea influx and ammonium efflux. After urea passes through OMPLA into the periplasm, it passes through the pH-gated inner membrane channel UreI into the cytoplasm where urease hydrolyses it into NH3 and CO2. Most of the NH3 becomes NH4+ that is likely to need an inner membrane channel to reach the periplasm. Two genes that are co-regulated with OMPLA in gastric Helicobacter operons could aid this transport. The NH4+ that might leave the cell through the OMPLA pore has been implicated in H. pylor’s pathogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s13099-017-0184-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hilde S Vollan
- Department of Clinical Molecular Biology (EpiGen), Division of Medicine, Akershus University Hospital and University of Oslo, PO box 28, 1478 Lørenskog, Norway.,Norwegian Institute of Public Health, Box 4404, Nydalen, 0403 Oslo, Norway
| | - Tone Tannæs
- Department of Clinical Molecular Biology (EpiGen), Division of Medicine, Akershus University Hospital and University of Oslo, PO box 28, 1478 Lørenskog, Norway
| | - Dominique A Caugant
- Norwegian Institute of Public Health, Box 4404, Nydalen, 0403 Oslo, Norway.,Department of Community Medicine and Global Health, Faculty of Medicine, University of Oslo, P.O. Box 1130, Blindern, 0318 Oslo, Norway
| | - Gert Vriend
- CMBI, Radboudumc, 6525 GA Nijmegen, The Netherlands
| | - Geir Bukholm
- Norwegian Institute of Public Health, Box 4404, Nydalen, 0403 Oslo, Norway.,Norwegian University of Life Sciences, PO Box 5003, 1430 Ås, Norway
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Altered Channel Conductance States and Gating of GABA A Receptors by a Pore Mutation Linked to Dravet Syndrome. eNeuro 2017; 4:eN-NWR-0251-16. [PMID: 28197552 PMCID: PMC5301078 DOI: 10.1523/eneuro.0251-16.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 01/19/2017] [Accepted: 01/19/2017] [Indexed: 11/21/2022] Open
Abstract
We identified a de novo missense mutation, P302L, in the γ-aminobutyric acid type A (GABAA) receptor γ2 subunit gene GABRG2 in a patient with Dravet syndrome using targeted next-generation sequencing. The mutation was in the cytoplasmic portion of the transmembrane segment M2 of the γ2 subunit that faces the pore lumen. GABAA receptor α1 and β3 subunits were coexpressed with wild-type (wt) γ2L or mutant γ2L(P302L) subunits in HEK 293T cells and cultured mouse cortical neurons. We measured currents using whole-cell and single-channel patch clamp techniques, surface and total expression levels using surface biotinylation and Western blotting, and potential structural perturbations in mutant GABAA receptors using structural modeling. The γ2(P302L) subunit mutation produced an ∼90% reduction of whole-cell current by increasing macroscopic desensitization and reducing GABA potency, which resulted in a profound reduction of GABAA receptor-mediated miniature IPSCs (mIPSCs). The conductance of the receptor channel was reduced to 24% of control conductance by shifting the relative contribution of the conductance states from high- to low-conductance levels with only slight changes in receptor surface expression. Structural modeling of the GABAA receptor in the closed, open, and desensitized states showed that the mutation was positioned to slow activation, enhance desensitization, and shift channels to a low-conductance state by reshaping the hour-glass-like pore cavity during transitions between closed, open, and desensitized states. Our study revealed a novel γ2 subunit missense mutation (P302L) that has a novel pathogenic mechanism to cause defects in the conductance and gating of GABAA receptors, which results in hyperexcitability and contributes to the pathogenesis of the genetic epilepsy Dravet syndrome.
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Adiban J, Jamali Y, Rafii-Tabar H. Modeling ion permeation through a bacterial voltage-gated calcium channel CaVAb using molecular dynamics simulations. MOLECULAR BIOSYSTEMS 2017; 13:208-214. [DOI: 10.1039/c6mb00690f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ca2+ion binds tightly to the center of the selectivity filter of voltage-gated calcium channels.
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Affiliation(s)
- Jamal Adiban
- Department of Medical Physics and Biomedical Engineering
- Faculty of Medicine
- Shahid Beheshti University of Medical Sciences
- Tehran
- Iran
| | - Yousef Jamali
- Department of Applied Mathematics
- School of Mathematical Sciences
- Tarbiat Modares University
- Tehran
- Iran
| | - Hashem Rafii-Tabar
- Department of Medical Physics and Biomedical Engineering
- Faculty of Medicine
- Shahid Beheshti University of Medical Sciences
- Tehran
- Iran
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Mazhab-Jafari MT, Rohou A, Schmidt C, Bueler SA, Benlekbir S, Robinson CV, Rubinstein JL. Atomic model for the membrane-embedded V O motor of a eukaryotic V-ATPase. Nature 2016; 539:118-122. [PMID: 27776355 DOI: 10.1038/nature19828] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/06/2016] [Indexed: 12/15/2022]
Abstract
Vacuolar-type ATPases (V-ATPases) are ATP-powered proton pumps involved in processes such as endocytosis, lysosomal degradation, secondary transport, TOR signalling, and osteoclast and kidney function. ATP hydrolysis in the soluble catalytic V1 region drives proton translocation through the membrane-embedded VO region via rotation of a rotor subcomplex. Variability in the structure of the intact enzyme has prevented construction of an atomic model for the membrane-embedded motor of any rotary ATPase. We induced dissociation and auto-inhibition of the V1 and VO regions of the V-ATPase by starving the yeast Saccharomyces cerevisiae, allowing us to obtain a ~3.9-Å resolution electron cryomicroscopy map of the VO complex and build atomic models for the majority of its subunits. The analysis reveals the structures of subunits ac8c'c″de and a protein that we identify and propose to be a new subunit (subunit f). A large cavity between subunit a and the c-ring creates a cytoplasmic half-channel for protons. The c-ring has an asymmetric distribution of proton-carrying Glu residues, with the Glu residue of subunit c″ interacting with Arg735 of subunit a. The structure suggests sequential protonation and deprotonation of the c-ring, with ATP-hydrolysis-driven rotation causing protonation of a Glu residue at the cytoplasmic half-channel and subsequent deprotonation of a Glu residue at a luminal half-channel.
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Affiliation(s)
- Mohammad T Mazhab-Jafari
- Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Alexis Rohou
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA
| | - Carla Schmidt
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Stephanie A Bueler
- Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Samir Benlekbir
- Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Carol V Robinson
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - John L Rubinstein
- Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Morrill GA, Kostellow AB. Molecular Properties of Globin Channels and Pores: Role of Cholesterol in Ligand Binding and Movement. Front Physiol 2016; 7:360. [PMID: 27656147 PMCID: PMC5011150 DOI: 10.3389/fphys.2016.00360] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/08/2016] [Indexed: 02/02/2023] Open
Abstract
Globins contain one or more cavities that control or affect such functions as ligand movement and ligand binding. Here we report that the extended globin family [cytoglobin (Cygb); neuroglobin (Ngb); myoglobin (Mb); hemoglobin (Hb) subunits Hba(α); and Hbb(β)] contain either a transmembrane (TM) helix or pore-lining region as well as internal cavities. Protein motif/domain analyses indicate that Ngb and Hbb each contain 5 cholesterol- binding (CRAC/CARC) domains and 1 caveolin binding motif, whereas the Cygb dimer has 6 cholesterol-binding domains but lacks caveolin-binding motifs. Mb and Hba each exhibit 2 cholesterol-binding domains and also lack caveolin-binding motifs. The Hb αβ-tetramer contains 14 cholesterol-binding domains. Computer algorithms indicate that Cygb and Ngb cavities display multiple partitions and C-terminal pore-lining regions, whereas Mb has three major cavities plus a C-terminal pore-lining region. The Hb tetramer exhibits a large internal cavity but the subunits differ in that they contain a C-terminal TM helix (Hba) and pore-lining region (Hbb). The cavities include 43 of 190 Cygb residues, 38 of 151 of Ngb residues, 55 of 154 Mb residues, and 137 of 688 residues in the Hb tetramer. Each cavity complex includes 6 to 8 residues of the TM helix or pore-lining region and CRAC/CARC domains exist within all cavities. Erythrocyte Hb αβ-tetramers are largely cytosolic but also bind to a membrane anion exchange protein, "band 3," which contains a large internal cavity and 12 TM helices (5 being pore-lining regions). The Hba TM helix may be the erythrocyte membrane "band 3" attachment site. "Band 3" contributes 4 caveolin binding motifs and 10 CRAC/CARC domains. Cholesterol binding may create lipid-disordered phases that alter globin cavities and facilitate ligand movement, permitting ion channel formation and conformational changes that orchestrate anion and ligand (O2, CO2, NO) movement within the large internal cavities and channels of the globins.
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Affiliation(s)
- Gene A Morrill
- Department of Physiology and Biophysics, Albert Einstein College of Medicine Bronx, NY, USA
| | - Adele B Kostellow
- Department of Physiology and Biophysics, Albert Einstein College of Medicine Bronx, NY, USA
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The role of receptor topology in the vitamin D3 uptake and Ca 2+ response systems. Biochem Biophys Res Commun 2016; 477:834-840. [DOI: 10.1016/j.bbrc.2016.06.143] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Accepted: 06/27/2016] [Indexed: 11/18/2022]
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77
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Manoharan P, Saravanan KM. Computational profiling of pore properties of outer membrane proteins. J Biomol Struct Dyn 2016; 35:2372-2381. [PMID: 27494049 DOI: 10.1080/07391102.2016.1220329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Prabu Manoharan
- a Centre of Excellence in Bioinformatics, School of Biotechnology , Madurai Kamaraj University , Madurai 625021 , Tamilnadu , India
| | - Konda Mani Saravanan
- b Centre of Advanced Study in Crystallography & Biophysics , University of Madras, Guindy Campus , Chennai 600025 , Tamilnadu , India
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Marracino P, Castellani F, Vernier PT, Liberti M, Apollonio F. Geometrical Characterization of an Electropore from Water Positional Fluctuations. J Membr Biol 2016; 250:11-19. [PMID: 27435217 DOI: 10.1007/s00232-016-9917-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 07/06/2016] [Indexed: 11/30/2022]
Abstract
We present here a new method for calculating the radius of a transmembrane pore in a phospholipid bilayer. To compare size-related properties of pores in bilayers of various compositions, generated and maintained under different physical and chemical conditions, reference metrics are needed. Operational metrics can be associated with some observed behavior. For example, pore size can be defined by the largest object that will pass through the length of the pore. The novelty of the present approach resides in the characterization of electropore geometry via a statistical approach, based on essential dynamics rules. We define the pore size geometrically with an algorithm for determining the pore radius. In particular, we extract the radius from the tri-dimensional surface of a defined pore region. The method is applied to a pore formed in a phospholipid bilayer by application of an external electric field. Although the details described here are specific for lipid pores in molecular dynamics simulations, the method can be generalized for any kind of pores for which appropriate structural information is available.
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Affiliation(s)
- P Marracino
- Department of Information Engineering, Electronics, and Telecommunications, Sapienza University of Rome, Rome, Italy.
| | - F Castellani
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA.,Biomedical Engineering Institute, Frank Batten College of Engineering and Technology, Old Dominion University, Norfolk, VA, 23529, USA
| | - P T Vernier
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA
| | - M Liberti
- Department of Information Engineering, Electronics, and Telecommunications, Sapienza University of Rome, Rome, Italy
| | - F Apollonio
- Department of Information Engineering, Electronics, and Telecommunications, Sapienza University of Rome, Rome, Italy
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79
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Installing hydrolytic activity into a completely de novo protein framework. Nat Chem 2016; 8:837-44. [DOI: 10.1038/nchem.2555] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 05/23/2016] [Indexed: 12/23/2022]
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80
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Azad AK, Ahmed J, Alum MA, Hasan MM, Ishikawa T, Sawa Y, Katsuhara M. Genome-Wide Characterization of Major Intrinsic Proteins in Four Grass Plants and Their Non-Aqua Transport Selectivity Profiles with Comparative Perspective. PLoS One 2016; 11:e0157735. [PMID: 27327960 PMCID: PMC4915720 DOI: 10.1371/journal.pone.0157735] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 06/04/2016] [Indexed: 11/27/2022] Open
Abstract
Major intrinsic proteins (MIPs), commonly known as aquaporins, transport not only water in plants but also other substrates of physiological significance and heavy metals. In most of the higher plants, MIPs are divided into five subfamilies (PIPs, TIPs, NIPs, SIPs and XIPs). Herein, we identified 68, 42, 38 and 28 full-length MIPs, respectively in the genomes of four monocot grass plants, specifically Panicum virgatum, Setaria italica, Sorghum bicolor and Brachypodium distachyon. Phylogenetic analysis showed that the grass plants had only four MIP subfamilies including PIPs, TIPs, NIPs and SIPs without XIPs. Based on structural analysis of the homology models and comparing the primary selectivity-related motifs [two NPA regions, aromatic/arginine (ar/R) selectivity filter and Froger's positions (FPs)] of all plant MIPs that have been experimentally proven to transport non-aqua substrates, we predicted the transport profiles of all MIPs in the four grass plants and also in eight other plants. Groups of MIP subfamilies based on ar/R selectivity filter and FPs were linked to the non-aqua transport profiles. We further deciphered the substrate selectivity profiles of the MIPs in the four grass plants and compared them with their counterparts in rice, maize, soybean, poplar, cotton, Arabidopsis thaliana, Physcomitrella patens and Selaginella moellendorffii. In addition to two NPA regions, ar/R filter and FPs, certain residues, especially in loops B and C, contribute to the functional distinctiveness of MIP groups. Expression analysis of transcripts in different organs indicated that non-aqua transport was related to expression of MIPs since most of the unexpressed MIPs were not predicted to facilitate the transport of non-aqua molecules. Among all MIPs in every plant, TIP (BdTIP1;1, SiTIP1;2, SbTIP2;1 and PvTIP1;2) had the overall highest mean expression. Our study generates significant information for understanding the diversity, evolution, non-aqua transport profiles and insight into comparative transport selectivity of plant MIPs, and provides tools for the development of transgenic plants.
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Affiliation(s)
- Abul Kalam Azad
- Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh
| | - Jahed Ahmed
- Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh
| | - Md. Asraful Alum
- Forensic DNA Laboratory of Bangladesh Police, Malibagh, Dhaka, Bangladesh
| | - Md. Mahbub Hasan
- Department of Genetic Engineering and Biotechnology, University of Chittagong, Chittagong 4331, Bangladesh
| | - Takahiro Ishikawa
- Department of Life Science and Biotechnology, Shimane University, Shimane 690–8504, Japan
| | - Yoshihiro Sawa
- Department of Life Science and Biotechnology, Shimane University, Shimane 690–8504, Japan
| | - Maki Katsuhara
- Institute of Plant Science and Resources, Okayama University, Chuo-2-chome, Kurashiki 710–0046, Japan
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81
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Molecular Dynamics Simulations and Structural Analysis to Decipher Functional Impact of a Twenty Residue Insert in the Ternary Complex of Mus musculus TdT Isoform. PLoS One 2016; 11:e0157286. [PMID: 27311013 PMCID: PMC4911049 DOI: 10.1371/journal.pone.0157286] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 05/26/2016] [Indexed: 01/08/2023] Open
Abstract
Insertions/deletions are common evolutionary tools employed to alter the structural and functional repertoire of protein domains. An insert situated proximal to the active site or ligand binding site frequently impacts protein function; however, the effect of distal indels on protein activity and/or stability are often not studied. In this paper, we have investigated a distal insert, which influences the function and stability of a unique DNA polymerase, called terminal deoxynucleotidyl transferase (TdT). TdT (EC:2.7.7.31) is a monomeric 58 kDa protein belonging to family X of eukaryotic DNA polymerases and known for its role in V(D)J recombination as well as in non-homologous end-joining (NHEJ) pathways. Two murine isoforms of TdT, with a length difference of twenty residues and having different biochemical properties, have been studied. All-atom molecular dynamics simulations at different temperatures and interaction network analyses were performed on the short and long-length isoforms. We observed conformational changes in the regions distal to the insert position (thumb subdomain) in the longer isoform, which indirectly affects the activity and stability of the enzyme through a mediating loop (Loop1). A structural rationale could be provided to explain the reduced polymerization rate as well as increased thermosensitivity of the longer isoform caused by peripherally located length variations within a DNA polymerase. These observations increase our understanding of the roles of length variants in introducing functional diversity in protein families in general.
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82
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Natchimuthu V, Bandaru S, Nayarisseri A, Ravi S. Design, synthesis and computational evaluation of a novel intermediate salt of N-cyclohexyl-N-(cyclohexylcarbamoyl)-4-(trifluoromethyl) benzamide as potential potassium channel blocker in epileptic paroxysmal seizures. Comput Biol Chem 2016; 64:64-73. [PMID: 27266485 DOI: 10.1016/j.compbiolchem.2016.05.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 04/11/2016] [Accepted: 05/19/2016] [Indexed: 01/26/2023]
Abstract
The narrow therapeutic range and limited pharmacokinetics of available Antiepileptic drugs (AEDs) have raised serious concerns in the proper management of epilepsy. To overcome this, the present study attempts to identify a candidate molecule targeting voltage gated potassium channels anticipated to have superior pharmacological than existing potassium channel blockers. The compound was synthesized by reacting (S)-(+)-2,3-dihydro-1H-pyrrolo[2,1-c][1,4] benzodiazepine5,11(10H,11aH)-dione with 4-(Trifluoromethyl) benzoic acid (C8H5F3O2) in DMF and N,N'-dicyclohexylcarbodiimide (DCC) which lead to the formation of an intermediate salt of N-cyclohexyl-N-(cyclohexylcarbamoyl)-4-(trifluoromethyl)benzamide with a perfect crystalline structure. The structure of the compound was characterized by FTIR, 1H NMR and 13C NMR analysis. The crystal structure is confirmed by single crystal X-ray diffraction analysis. The Structure-Activity Relationship (SAR) studies revealed that substituent of fluoro or trifluoromethyl moiety into the compound had a great effect on the biological activity in comparison to clinically used drugs. Employing computational approaches the compound was further tested for its affinity against potassium protein structure by molecular docking in addition, bioactivity and ADMET properties were predicted through computer aided programs.
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Affiliation(s)
- V Natchimuthu
- PG & Research Department of Physics, National College (Affiliated to Bharathidasan University), Tiruchirapalli, 620 001 Tamil Nadu, India
| | - Srinivas Bandaru
- Bioinformatics Research Laboratory, Eminent Biosciences, Vijaynagar, Indore 452010 Madhya Pradesh, India
| | - Anuraj Nayarisseri
- Bioinformatics Research Laboratory, Eminent Biosciences, Vijaynagar, Indore 452010 Madhya Pradesh, India
| | - S Ravi
- PG & Research Department of Physics, National College (Affiliated to Bharathidasan University), Tiruchirapalli, 620 001 Tamil Nadu, India.
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83
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Pavelka A, Sebestova E, Kozlikova B, Brezovsky J, Sochor J, Damborsky J. CAVER: Algorithms for Analyzing Dynamics of Tunnels in Macromolecules. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2016; 13:505-517. [PMID: 27295634 DOI: 10.1109/tcbb.2015.2459680] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The biological function of a macromolecule often requires that a small molecule or ion is transported through its structure. The transport pathway often leads through void spaces in the structure. The properties of transport pathways change significantly in time; therefore, the analysis of a trajectory from molecular dynamics rather than of a single static structure is needed for understanding the function of pathways. The identification and analysis of transport pathways are challenging because of the high complexity and diversity of macromolecular shapes, the thermal motion of their atoms, and the large amount of conformations needed to properly describe conformational space of protein structure. In this paper, we describe the principles of the CAVER 3.0 algorithms for the identification and analysis of properties of transport pathways both in static and dynamic structures. Moreover, we introduce the improved clustering solution for finding tunnels in macromolecules, which is included in the latest CAVER 3.02 version. Voronoi diagrams are used to identify potential pathways in each snapshot of a molecular dynamics trajectory and clustering is then used to find the correspondence between tunnels from different snapshots. Furthermore, the geometrical properties of pathways and their evolution in time are computed and visualized.
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84
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Sreedharan S, Kothandan G, Sankaranarayanan K. Structural insights into the Aedes aegypti aquaporins and aquaglyceroporins – an in silico study. J Recept Signal Transduct Res 2016; 36:543-557. [DOI: 10.3109/10799893.2016.1141954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Sandhya Sreedharan
- AU-KBC Research Centre, Madras Institute of Technology, Anna University, Chennai, India and
| | - Gugan Kothandan
- Centre for Advanced Study in Crystallography and Biophysics, Guindy Campus, University of Madras, Chennai, India
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85
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Song L, Nguyen N, Deshmukh RK, Patil GB, Prince SJ, Valliyodan B, Mutava R, Pike SM, Gassmann W, Nguyen HT. Soybean TIP Gene Family Analysis and Characterization of GmTIP1;5 and GmTIP2;5 Water Transport Activity. FRONTIERS IN PLANT SCIENCE 2016; 7:1564. [PMID: 27818669 PMCID: PMC5073556 DOI: 10.3389/fpls.2016.01564] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 10/04/2016] [Indexed: 05/04/2023]
Abstract
Soybean, one of the most important crops worldwide, is severely affected by abiotic stress. Drought and flooding are the major abiotic stresses impacting soybean yield. In this regard, understanding water uptake by plants, its utilization and transport has great importance. In plants, water transport is mainly governed by channel forming aquaporin proteins (AQPs). Tonoplast intrinsic proteins (TIPs) belong to the plant-specific AQP subfamily and are known to have a role in abiotic stress tolerance. In this study, 23 soybean TIP genes were identified based on the latest soybean genome annotation. TIPs were characterized based on conserved structural features and phylogenetic distribution. Expression analysis of soybean TIP genes in various tissues and under abiotic stress conditions demonstrated tissue/stress-response specific differential expression. The natural variations for TIP genes were analyzed using whole genome re-sequencing data available for a set of 106 diverse soybean genotypes including wild types, landraces and elite lines. Results revealed 81 single-nucleotide polymorphisms (SNPs) and several large insertions/deletions in the coding region of TIPs. Among these, non-synonymous SNPs are most likely to have a greater impact on protein function and are candidates for molecular studies as well as for the development of functional markers to assist breeding. The solute transport function of two TIPs was further validated by expression in Xenopus laevis oocytes. GmTIP1;5 was shown to facilitate the rapid movement of water across the oocyte membrane, while GmTIP2;5 facilitated the movement of water and boric acid. The present study provides an initial insight into the possible roles of soybean TIP genes under abiotic stress conditions. Our results will facilitate elucidation of their precise functions during abiotic stress responses and plant development, and will provide potential breeding targets for modifying water movement in soybean.
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Affiliation(s)
- Li Song
- Division of Plant Science, National Center for Soybean Biotechnology, University of MissouriColumbia, MO, USA
| | - Na Nguyen
- Division of Plant Science, National Center for Soybean Biotechnology, University of MissouriColumbia, MO, USA
| | | | - Gunvant B. Patil
- Division of Plant Science, National Center for Soybean Biotechnology, University of MissouriColumbia, MO, USA
| | - Silvas J. Prince
- Division of Plant Science, National Center for Soybean Biotechnology, University of MissouriColumbia, MO, USA
| | - Babu Valliyodan
- Division of Plant Science, National Center for Soybean Biotechnology, University of MissouriColumbia, MO, USA
| | - Raymond Mutava
- Division of Plant Science, National Center for Soybean Biotechnology, University of MissouriColumbia, MO, USA
| | - Sharon M. Pike
- Division of Plant Sciences and Interdisciplinary Plant Group, Christopher S. Bond Life Sciences Center, University of MissouriColumbia, MO, USA
| | - Walter Gassmann
- Division of Plant Sciences and Interdisciplinary Plant Group, Christopher S. Bond Life Sciences Center, University of MissouriColumbia, MO, USA
| | - Henry T. Nguyen
- Division of Plant Science, National Center for Soybean Biotechnology, University of MissouriColumbia, MO, USA
- *Correspondence: Henry T. Nguyen,
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86
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Tong X, Aoyama H, Sudhakar S, Chen H, Shilton BH, Bai D. The First Extracellular Domain Plays an Important Role in Unitary Channel Conductance of Cx50 Gap Junction Channels. PLoS One 2015; 10:e0143876. [PMID: 26625162 PMCID: PMC4666595 DOI: 10.1371/journal.pone.0143876] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 11/10/2015] [Indexed: 11/28/2022] Open
Abstract
Gap junction (GJ) channels provide direct passage for ions and small molecules to be exchanged between neighbouring cells and are crucial for many physiological processes. GJ channels can be gated by transjunctional voltage (known as Vj-gating) and display a wide range of unitary channel conductance (γj), yet the domains responsible for Vj-gating and γj are not fully clear. The first extracellular domain (E1) of several connexins has been shown to line part of their GJ channel pore and play important roles in Vj-gating properties and/or ion permeation selectivity. To test roles of the E1 of Cx50 GJ channels, we generated a chimera, Cx50Cx36E1, where the E1 domain of Cx50 was replaced with that of Cx36, a connexin showing quite distinct Vj-gating and γj from those of Cx50. Detailed characterizations of the chimera and three point mutants in E1 revealed that, although the E1 domain is important in determining γj, the E1 domain of Cx36 is able to effectively function within the context of the Cx50 channel with minor changes in Vj-gating properties, indicating that sequence differences between the E1 domains in Cx36 and Cx50 cannot account for their drastic differences in Vj-gating and γj. Our homology models of the chimera and the E1 mutants revealed that electrostatic properties of the pore-lining residues and their contribution to the electric field in the pore are important factors for the rate of ion permeation of Cx50 and possibly other GJ channels.
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Affiliation(s)
- Xiaoling Tong
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Hiroshi Aoyama
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Swathy Sudhakar
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Honghong Chen
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Brian H. Shilton
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
| | - Donglin Bai
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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87
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Pliotas C, Dahl ACE, Rasmussen T, Mahendran KR, Smith TK, Marius P, Gault J, Banda T, Rasmussen A, Miller S, Robinson CV, Bayley H, Sansom MSP, Booth IR, Naismith JH. The role of lipids in mechanosensation. Nat Struct Mol Biol 2015; 22:991-8. [PMID: 26551077 PMCID: PMC4675090 DOI: 10.1038/nsmb.3120] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 10/06/2015] [Indexed: 12/13/2022]
Abstract
The ability of proteins to sense membrane tension is pervasive in biology. A higher-resolution structure of the Escherichia coli small-conductance mechanosensitive channel MscS identifies alkyl chains inside pockets formed by the transmembrane helices (TMs). Purified MscS contains E. coli lipids, and fluorescence quenching demonstrates that phospholipid acyl chains exchange between bilayer and TM pockets. Molecular dynamics and biophysical analyses show that the volume of the pockets and thus the number of lipid acyl chains within them decreases upon channel opening. Phospholipids with one acyl chain per head group (lysolipids) displace normal phospholipids (with two acyl chains) from MscS pockets and trigger channel opening. We propose that the extent of acyl-chain interdigitation in these pockets determines the conformation of MscS. When interdigitation is perturbed by increased membrane tension or by lysolipids, the closed state becomes unstable, and the channel gates.
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Affiliation(s)
- Christos Pliotas
- Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews, UK
| | | | - Tim Rasmussen
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | | | - Terry K Smith
- Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews, UK
| | - Phedra Marius
- Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews, UK
| | - Joseph Gault
- Department of Chemistry, University of Oxford, Oxford, UK
| | - Thandiwe Banda
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Akiko Rasmussen
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Samantha Miller
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | | | - Hagan Bayley
- Department of Chemistry, University of Oxford, Oxford, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Ian R Booth
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - James H Naismith
- Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews, UK
- State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China
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88
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PrinCCes: Continuity-based geometric decomposition and systematic visualization of the void repertoire of proteins. J Mol Graph Model 2015; 62:118-127. [PMID: 26409191 DOI: 10.1016/j.jmgm.2015.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Revised: 07/20/2015] [Accepted: 09/14/2015] [Indexed: 11/20/2022]
Abstract
Grooves and pockets on the surface, channels through the protein, the chambers or cavities, and the tunnels connecting the internal points to each other or to the external fluid environment are fundamental determinants of a wide range of biological functions. PrinCCes (Protein internal Channel & Cavity estimation) is a computer program supporting the visualization of voids. It includes a novel algorithm for the decomposition of the entire void volume of the protein or protein complex to individual entities. The decomposition is based on continuity. An individual void is defined by uninterrupted extension in space: a spherical probe can freely move between any two internal locations of a continuous void. Continuous voids are detected irrespective of their topological complexity, they may contain any number of holes and bifurcations. The voids of a protein can be visualized one by one or in combinations as triangulated surfaces. The output is automatically exported to free VMD (Visual Molecular Dynamics) or Chimera software, allowing the 3D rotation of the surfaces and the production of publication quality images. PrinCCes with graphic user interface and command line versions are available for MS Windows and Linux. The source code and executable can be downloaded at any of the following links: http://scholar.semmelweis.hu/czirjakgabor/s/princces/#t1 https://github.com/CzirjakGabor/PrinCCes http://1drv.ms/1bP9iJ3.
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89
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Morrill GA, Kostellow AB, Gupta RK. Transmembrane helices in "classical" nuclear reproductive steroid receptors: a perspective. NUCLEAR RECEPTOR SIGNALING 2015; 13:e003. [PMID: 26430393 PMCID: PMC4590301 DOI: 10.1621/nrs.13003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 05/28/2015] [Indexed: 12/25/2022]
Abstract
Abstract Steroid receptors of the nuclear receptor superfamily are proposed to be either: 1) located in the cytosol and moved to the cell nucleus upon activation, 2) tethered to the inside of the plasma membrane, or 3) retained in the nucleus until free steroid hormone enters and activates specific receptors. Using computational methods to analyze peptide receptor topology, we find that the “classical” nuclear receptors for progesterone (PRB/PGR), androgen (ARB/AR) and estrogen (ER1/ESR1) contain two transmembrane helices (TMH) within their ligand-binding domains (LBD).The MEMSAT-SVM algorithm indicates that ARB and ER2 (but not PRB or ER1) contain a pore-lining (channel-forming) region which may merge with other pore-lining regions to form a membrane channel. ER2 lacks a TMH, but contains a single pore-lining region. The MemBrain algorithm predicts that PRB, ARB and ER1 each contain one TMH plus a half TMH separated by 51 amino acids.ER2 contains two half helices. The TM-2 helices of ARB, ER1 and ER2 each contain 9-13 amino acid motifs reported to translocate the receptor to the plasma membrane, as well as cysteine palmitoylation sites. PoreWalker analysis of X-ray crystallographic data identifies a pore or channel within the LBDs of ARB and ER1 and predicts that 70 and 72 residues are pore-lining residues, respectively. The data suggest that (except for ER2), cytosolic receptors become anchored to the plasma membrane following synthesis. Half-helices and pore-lining regions in turn form functional ion channels and/or facilitate passive steroid uptake into the cell. In perspective, steroid-dependent insertion of “classical” receptors containing pore-lining regions into the plasma membrane may regulate permeability to ions such as Ca2+, Na+ or K+, as well as facilitate steroid translocation into the nucleus.
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Affiliation(s)
- Gene A Morrill
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Adele B Kostellow
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Raj K Gupta
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
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90
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Trembath-Reichert E, Wilson JP, McGlynn SE, Fischer WW. Four hundred million years of silica biomineralization in land plants. Proc Natl Acad Sci U S A 2015; 112:5449-54. [PMID: 25825729 PMCID: PMC4418875 DOI: 10.1073/pnas.1500289112] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Biomineralization plays a fundamental role in the global silicon cycle. Grasses are known to mobilize significant quantities of Si in the form of silica biominerals and dominate the terrestrial realm today, but they have relatively recent origins and only rose to taxonomic and ecological prominence within the Cenozoic Era. This raises questions regarding when and how the biological silica cycle evolved. To address these questions, we examined silica abundances of extant members of early-diverging land plant clades, which show that silica biomineralization is widespread across terrestrial plant linages. Particularly high silica abundances are observed in lycophytes and early-diverging ferns. However, silica biomineralization is rare within later-evolving gymnosperms, implying a complex evolutionary history within the seed plants. Electron microscopy and X-ray spectroscopy show that the most common silica-mineralized tissues include the vascular system, epidermal cells, and stomata, which is consistent with the hypothesis that biomineralization in plants is frequently coupled to transpiration. Furthermore, sequence, phylogenetic, and structural analysis of nodulin 26-like intrinsic proteins from diverse plant genomes points to a plastic and ancient capacity for silica accumulation within terrestrial plants. The integration of these two comparative biology approaches demonstrates that silica biomineralization has been an important process for land plants over the course of their >400 My evolutionary history.
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Affiliation(s)
| | | | - Shawn E McGlynn
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125; Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji-shi, Tokyo 192-0397, Japan
| | - Woodward W Fischer
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
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91
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Kim JK, Cho Y, Lee M, Laskowski RA, Ryu SE, Sugihara K, Kim DS. BetaCavityWeb: a webserver for molecular voids and channels. Nucleic Acids Res 2015; 43:W413-8. [PMID: 25904629 PMCID: PMC4489219 DOI: 10.1093/nar/gkv360] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 04/07/2015] [Indexed: 11/24/2022] Open
Abstract
Molecular cavities, which include voids and channels, are critical for molecular function. We present a webserver, BetaCavityWeb, which computes these cavities for a given molecular structure and a given spherical probe, and reports their geometrical properties: volume, boundary area, buried area, etc. The server's algorithms are based on the Voronoi diagram of atoms and its derivative construct: the beta-complex. The correctness of the computed result and computational efficiency are both mathematically guaranteed. BetaCavityWeb is freely accessible at the Voronoi Diagram Research Center (VDRC) (http://voronoi.hanyang.ac.kr/betacavityweb).
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Affiliation(s)
- Jae-Kwan Kim
- Vorononi Diagram Research Center, Hanyang University, Korea
| | - Youngsong Cho
- Vorononi Diagram Research Center, Hanyang University, Korea
| | - Mokwon Lee
- School of Mechanical Engineering, Hanyang University, Korea
| | | | - Seong Eon Ryu
- Department of Bioengineering, Hanyang University, Korea
| | - Kokichi Sugihara
- Meiji Institute for Advanced Study of Mathematical Sciences, Tokyo, Japan
| | - Deok-Soo Kim
- Vorononi Diagram Research Center, Hanyang University, Korea School of Mechanical Engineering, Hanyang University, Korea
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92
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Masood TB, Sandhya S, Chandra N, Natarajan V. CHEXVIS: a tool for molecular channel extraction and visualization. BMC Bioinformatics 2015; 16:119. [PMID: 25888118 PMCID: PMC4411761 DOI: 10.1186/s12859-015-0545-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/20/2015] [Indexed: 12/11/2022] Open
Abstract
Background Understanding channel structures that lead to active sites or traverse the molecule is important in the study of molecular functions such as ion, ligand, and small molecule transport. Efficient methods for extracting, storing, and analyzing protein channels are required to support such studies. Further, there is a need for an integrated framework that supports computation of the channels, interactive exploration of their structure, and detailed visual analysis of their properties. Results We describe a method for molecular channel extraction based on the alpha complex representation. The method computes geometrically feasible channels, stores both the volume occupied by the channel and its centerline in a unified representation, and reports significant channels. The representation also supports efficient computation of channel profiles that help understand channel properties. We describe methods for effective visualization of the channels and their profiles. These methods and the visual analysis framework are implemented in a software tool, ChExVis. We apply the method on a number of known channel containing proteins to extract pore features. Results from these experiments on several proteins show that ChExVis performance is comparable to, and in some cases, better than existing channel extraction techniques. Using several case studies, we demonstrate how ChExVis can be used to study channels, extract their properties and gain insights into molecular function. Conclusion ChExVis supports the visual exploration of multiple channels together with their geometric and physico-chemical properties thereby enabling the understanding of the basic biology of transport through protein channels. The ChExVis web-server is freely available at http://vgl.serc.iisc.ernet.in/chexvis/. The web-server is supported on all modern browsers with latest Java plug-in. Electronic supplementary material The online version of this article (doi:10.1186/s12859-015-0545-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Talha Bin Masood
- Department of Computer Science and Automation, Indian Institute of Science, Bangalore, 560012, India.
| | - Sankaran Sandhya
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India.
| | - Nagasuma Chandra
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India.
| | - Vijay Natarajan
- Department of Computer Science and Automation, Indian Institute of Science, Bangalore, 560012, India. .,Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore, 560012, India.
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93
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Patel SK, Khedkar VM, Jha PC, Jasrai YT, Pandya HA, George LB, Highland HN, Skelton AA. Molecular interaction of selected phytochemicals under the charged environment ofPlasmodium falciparumchloroquine resistance transporter (PfCRT) model. J Biomol Struct Dyn 2015; 34:290-303. [DOI: 10.1080/07391102.2015.1028449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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94
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Computational analysis of the extracellular domain of the Ca²⁺-sensing receptor: an alternate model for the Ca²⁺ sensing region. Biochem Biophys Res Commun 2015; 459:36-41. [PMID: 25701780 DOI: 10.1016/j.bbrc.2015.02.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 02/10/2015] [Indexed: 11/21/2022]
Abstract
The extracellular Ca(2+) sensing receptor (CaSR) belongs to Class C G-protein-coupled receptors (GPCRs) which include receptors for amino acids, γ-aminobutyric acid and glutamate neurotransmitters. CaSR has been described as having an extended sequence containing a Ca(2+) binding pocket within an extracellular amino (N)-terminal domain, called a Venus Fly Trap (VFT) module. CaSR is thought to consist of three domains: 1) a Ca(2+-)sensory domain, 2) a region containing 7 transmembrane (TM) helices, and 3) a carboxy (C)-terminal tail. We find that SPOCTOPUS (a combination of hidden Markov models and artificial neural networks) predicts that Homo sapiens CaSR contains two additional TM helices ((190)D - G(210); (262)S-E(282)), with the second TM helix containing a pore-lining region ((265)K - I(280)). This predicts that the putative Ca(2+) sensory domain is within an extracellular loop, N-terminal to the highly conserved heptahelical bundle. This loop contains both the cysteine-rich domain ((537)V - C(598)) and a 14 residue "linker" sequence ((599)I - F(612)) thought to support signal transmission to the heptahelical bundle. Thus domain 1 may contain a 189 residue N-terminal extracellular region followed successively by TM-1, a short intracellular loop, TM-2 and a 329 residue extracellular loop; rather than the proposed 620 residue VFT module based on crystallography of the N-terminal region of mGluR1. Since the topologies of the two proteins differ, the published CaSR VFT model is questionable. CaSR also contains multiple caveolin-binding motifs and cholesterol-binding (CRAC/CARC) domains, facilitating localization to plasma membrane lipid rafts. Ion sensing may involve combination of pore-lining regions from CaSR dimers and CaSR-bound caveolins to form ion channels capable of monitoring ionized Ca(2+) levels.
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95
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Abstract
Lactose permease (LacY), a paradigm for the largest family of membrane transport proteins, catalyzes the coupled translocation of a galactoside and an H(+) across the Escherichia coli membrane (galactoside/H(+) symport). Initial X-ray structures reveal N- and C-terminal domains, each with six largely irregular transmembrane helices surrounding an aqueous cavity open to the cytoplasm. Recently, a structure with a narrow periplasmic opening and an occluded galactoside was obtained, confirming many observations and indicating that sugar binding involves induced fit. LacY catalyzes symport by an alternating access mechanism. Experimental findings garnered over 45 y indicate the following: (i) The limiting step for lactose/H(+) symport in the absence of the H(+) electrochemical gradient (∆µ̃H+) is deprotonation, whereas in the presence of ∆µ̃H+, the limiting step is opening of apo LacY on the other side of the membrane; (ii) LacY must be protonated to bind galactoside (the pK for binding is ∼10.5); (iii) galactoside binding and dissociation, not ∆µ̃H+, are the driving forces for alternating access; (iv) galactoside binding involves induced fit, causing transition to an occluded intermediate that undergoes alternating access; (v) galactoside dissociates, releasing the energy of binding; and (vi) Arg302 comes into proximity with protonated Glu325, causing deprotonation. Accumulation of galactoside against a concentration gradient does not involve a change in Kd for sugar on either side of the membrane, but the pKa (the affinity for H(+)) decreases markedly. Thus, transport is driven chemiosmotically but, contrary to expectation, ∆µ̃H+ acts kinetically to control the rate of the process.
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96
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Efremov RG, Leitner A, Aebersold R, Raunser S. Architecture and conformational switch mechanism of the ryanodine receptor. Nature 2014; 517:39-43. [DOI: 10.1038/nature13916] [Citation(s) in RCA: 250] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Accepted: 10/06/2014] [Indexed: 12/11/2022]
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97
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Thomson AR, Wood CW, Burton AJ, Bartlett GJ, Sessions RB, Brady RL, Woolfson DN. Computational design of water-soluble α-helical barrels. Science 2014; 346:485-8. [DOI: 10.1126/science.1257452] [Citation(s) in RCA: 270] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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98
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Morrill GA, Kostellow AB, Gupta RK. The pore-lining regions in cytochrome c oxidases: A computational analysis of caveolin, cholesterol and transmembrane helix contributions to proton movement. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2838-51. [PMID: 25037006 DOI: 10.1016/j.bbamem.2014.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/19/2014] [Accepted: 07/08/2014] [Indexed: 11/30/2022]
Abstract
Cytochrome c oxidase (CcO) is the terminal enzyme in the electron transfer chain. CcO catalyzes a four electron reduction of O2 to water at a catalytic site formed by high-spin heme (a3) and copper atoms (CuB). While it is recognized that proton movement is coupled to oxygen reduction, the proton channel(s) have not been well defined. Using computational methods developed to study protein topology, membrane channels and 3D packing arrangements within transmembrane (TM) helix arrays, we find that subunit-1 (COX-1), subunit-2 (COX-2) and subunit-3 (COX-3) contribute 139, 46 and 25 residues, respectively, to channel formation between the mitochondrial matrix and intermembrane space. Nine of 12 TM helices in COX-1, both helices in COX-2 and 5 of the 6 TM helices in COX-3 are pore-lining regions (possible channel formers). Heme a3 and the CuB sites (as well as the CuA center of COX-2) are located within the channel that includes TM-6, TM-7, TM-10 and TM-11 of COX-1 and are associated with multiple cholesterol and caveolin-binding (CB) motifs. Sequence analysis identifies five CB motifs within COX-1, two within COX-2 and four within COX-3; each caveolin containing a pore-lining helix C-terminal to a TM helix-turn-helix. Channel formation involves interaction between multiple pore-lining regions within protein subunits and/or dimers. PoreWalker analysis lends support to the D-channel model of proton translocation. Under physiological conditions, caveolins may introduce channel formers juxtaposed to those in COX-1, COX-2 and COX-3, which together with cholesterol may form channel(s) essential for proton translocation through the inner mitochondrial membrane.
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Affiliation(s)
- Gene A Morrill
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA.
| | - Adele B Kostellow
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA
| | - Raj K Gupta
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA
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Kozlikova B, Sebestova E, Sustr V, Brezovsky J, Strnad O, Daniel L, Bednar D, Pavelka A, Manak M, Bezdeka M, Benes P, Kotry M, Gora A, Damborsky J, Sochor J. CAVER Analyst 1.0: graphic tool for interactive visualization and analysis of tunnels and channels in protein structures. Bioinformatics 2014; 30:2684-5. [DOI: 10.1093/bioinformatics/btu364] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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100
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Edelheit O, Ben-Shahar R, Dascal N, Hanukoglu A, Hanukoglu I. Conserved charged residues at the surface and interface of epithelial sodium channel subunits--roles in cell surface expression and the sodium self-inhibition response. FEBS J 2014; 281:2097-111. [PMID: 24571549 DOI: 10.1111/febs.12765] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/12/2014] [Accepted: 02/24/2014] [Indexed: 01/18/2023]
Abstract
The epithelial sodium channel (ENaC) is composed of three homologous subunits that form a triangular pyramid-shaped funnel, anchored in the membrane with a stem of six transmembrane domains. We examined the structure-function relationships of 17 conserved charged residues on the surface of the ectodomain of human γ-ENaC subunit by alanine mutagenesis and co-expression with α- and β-ENaC subunits in Xenopus oocytes. The results showed that Na(+) conductance of cells expressing these mutants can be accounted for by two parameters: (a) the ENaC density on the cell surface as measured by the fluorescence of an α-EnaC-yellow fluorescent protein hybrid and (b) the sodium self-inhibition (SSI) response that reflects the open probability of the channel (Po). Overall, the activity of all 17 mutants was correlated with surface levels of ENaC. There was no significant correlation between these parameters measured for α- and γ-ENaC subunit mutants at nine homologous positions. Thus, the functions of most of the homologous surface residues examined differ between the two subunits. Only four mutants (K328, D510, R514 and E518) significantly reduced the SSI response. The α-ENaC homologs of three of these (R350, E530 and E538) also severely affected the SSI response. The cASIC1 homologs of these (K247, E417, Q421) are located at the interface between subunits, on or about the ion pathway at the rotational symmetry axis in the center of the trimer. Thus, it is likely that these residues are involved in conformational changes that lead to channel constriction and the SSI response upon Na(+) ion flooding.
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Affiliation(s)
- Oded Edelheit
- Sackler School of Medicine, Tel-Aviv University, Israel
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