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https://www.readbyqxmd.com/read/28340512/activation-mechanisms-of-%C3%AE-v%C3%AE-3-integrin-by-binding-to-fibronectin-a-computational-study
#1
Lingyun Wang, Di Pan, Qi Yan, Yuhua Song
Integrin αVβ3 plays an important role in regulating cellular activities and in human diseases. Although the structure of αVβ3 has been studied by crystallography and electron microscopy, the detailed activation mechanism of integrin αVβ3 induced by fibronectin (Fn) remains unclear. In this study, we investigated the conformational and dynamical motion changes of Mn(2+) -bound integrin αVβ3 by binding to Fn with molecular dynamics simulations. Results showed that Fn binding to integrin αVβ3 caused the changes of the conformational flexibility of αVβ3 domains, the essential mode of motion for the domains of αV subunit and β3 subunit and the degrees of correlated motion of residues between the domains of αV subunit and β3 subunit of integrin αVβ3...
March 24, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28340354/mechanism-of-substrate-translocation-in-an-alternating-access-transporter
#2
Naomi R Latorraca, Nathan M Fastman, A J Venkatakrishnan, Wolf B Frommer, Ron O Dror, Liang Feng
Transporters shuttle molecules across cell membranes by alternating among distinct conformational states. Fundamental questions remain about how transporters transition between states and how such structural rearrangements regulate substrate translocation. Here, we capture the translocation process by crystallography and unguided molecular dynamics simulations, providing an atomic-level description of alternating access transport. Simulations of a SWEET-family transporter initiated from an outward-open, glucose-bound structure reported here spontaneously adopt occluded and inward-open conformations...
March 23, 2017: Cell
https://www.readbyqxmd.com/read/28340353/molecular-structure-of-the-human-cftr-ion-channel
#3
Fangyu Liu, Zhe Zhang, László Csanády, David C Gadsby, Jue Chen
The cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-binding cassette (ABC) transporter that uniquely functions as an ion channel. Here, we present a 3.9 Å structure of dephosphorylated human CFTR without nucleotides, determined by electron cryomicroscopy (cryo-EM). Close resemblance of this human CFTR structure to zebrafish CFTR under identical conditions reinforces its relevance for understanding CFTR function. The human CFTR structure reveals a previously unresolved helix belonging to the R domain docked inside the intracellular vestibule, precluding channel opening...
March 23, 2017: Cell
https://www.readbyqxmd.com/read/28340295/response-of-catalase-of-the-mouse-primary-hepatocytes-to-sodium-dodecylbenzene-sulfonate-and-the-underlying-molecular-mechanisms
#4
Jing Wang, Jiaxi Wang, Lu Zhang, Rutao Liu, Wansong Zong
This study investigated the adverse effects of sodium dodecylbenzene sulfonates (SDBS) on the mouse primary hepatocytes by conducting cell viability, intracellular oxidative stress level and catalase (CAT) activity assays. It was shown that SDBS altered CAT activities, triggered oxidative stress, and thus exhibited cytotoxicity to the hepatocytes. Both the stimulation of intracellular CAT production and the inhibition of molecular CAT activity contributed to intracellular CAT activity change. Molecular mechanisms underlying CAT activity inhibition and structural changes were explored by isothermal titration calorimetry, multi-spectroscopy and molecular docking studies...
March 24, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28339206/utilizing-electron-spin-echo-envelope-modulation-to-distinguish-between-the-local-secondary-structures-of-an-%C3%AE-helix-and-an-amphipathic-310-helical-peptide
#5
Lauren Bottorf, Sophia Rafferty, Indra Dev Sahu, Robert M McCarrick, Gary A Lorigan
Electron Spin Echo Envelope Modulation (ESEEM) spectroscopy was used to distinguish between the local secondary structures of an α-helix and a 310-helix. Previously, we have shown that ESEEM spectroscopy in combination with site-directed spin labeling (SDSL) and 2H-labeled amino acids (i) can probe the local secondary structure of α-helices, resulting in an obvious deuterium modulation pattern, where i+4 positions generally show larger 2H ESEEM peak intensities than i+3 positions. Here, we have hypothesized that due to the unique turn periodicities of an α-helix (3...
March 24, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28335521/gene-transformation-induced-changes-in-chemical-functional-group-features-and-molecular-structure-conformation-in-alfalfa-plants-co-expressing-lc-bhlh-and-c1-myb-transcriptive-flavanoid-regulatory-genes-effects-of-single-gene-and-two-gene-insertion
#6
Ravindra G Heendeniya, Peiqiang Yu
Alfalfa (Medicago sativa L.) genotypes transformed with Lc-bHLH and Lc transcription genes were developed with the intention of stimulating proanthocyanidin synthesis in the aerial parts of the plant. To our knowledge, there are no studies on the effect of single-gene and two-gene transformation on chemical functional groups and molecular structure changes in these plants. The objective of this study was to use advanced molecular spectroscopy with multivariate chemometrics to determine chemical functional group intensity and molecular structure changes in alfalfa plants when co-expressing Lc-bHLH and C1-MYB transcriptive flavanoid regulatory genes in comparison with non-transgenic (NT) and AC Grazeland (ACGL) genotypes...
March 20, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28335314/effects-of-g-quadruplex-topology-on-electronic-transfer-integrals
#7
Wenming Sun, Daniele Varsano, Rosa Di Felice
G-quadruplex is a quadruple helical form of nucleic acids that can appear in guanine-rich parts of the genome. The basic unit is the G-tetrad, a planar assembly of four guanines connected by eight hydrogen bonds. Its rich topology and its possible relevance as a drug target for a number of diseases have stimulated several structural studies. The superior stiffness and electronic π-π overlap between consecutive G-tetrads suggest exploitation for nanotechnologies. Here we inspect the intimate link between the structure and the electronic properties, with focus on charge transfer parameters...
October 15, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28334976/a-sensitivity-analysis-of-rna-folding-nearest-neighbor-parameters-identifies-a-subset-of-free-energy-parameters-with-the-greatest-impact-on-rna-secondary-structure-prediction
#8
Jeffrey Zuber, Hongying Sun, Xiaoju Zhang, Iain McFadyen, David H Mathews
Nearest neighbor parameters for estimating the folding energy changes of RNA secondary structures are used in structure prediction and analysis. Despite their widespread application, a comprehensive analysis of the impact of each parameter on the precision of calculations had not been conducted. To identify the parameters with greatest impact, a sensitivity analysis was performed on the 291 parameters that compose the 2004 version of the free energy nearest neighbor rules. Perturbed parameter sets were generated by perturbing each parameter independently...
March 15, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334932/ribosome-dependent-vibrio-cholerae-mrnase-higb2-is-regulated-by-a-%C3%AE-strand-sliding-mechanism
#9
San Hadži, Abel Garcia-Pino, Sarah Haesaerts, Dukas Jurenas, Kenn Gerdes, Jurij Lah, Remy Loris
Toxin-antitoxin (TA) modules are small operons involved in bacterial stress response and persistence. higBA operons form a family of TA modules with an inverted gene organization and a toxin belonging to the RelE/ParE superfamily. Here, we present the crystal structures of chromosomally encoded Vibrio cholerae antitoxin (VcHigA2), toxin (VcHigB2) and their complex, which show significant differences in structure and mechanisms of function compared to the higBA module from plasmid Rts1, the defining member of the family...
February 28, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334863/consecutive-non-natural-pz-nucleobase-pairs-in-dna-impact-helical-structure-as-seen-in-50-%C3%AE-s-molecular-dynamics-simulations
#10
Robert W Molt, Millie M Georgiadis, Nigel G J Richards
Little is known about the influence of multiple consecutive 'non-standard' ( , 6-amino-5-nitro-2(1H)-pyridone, and , 2-amino-imidazo[1,2-a]-1,3,5-triazin-4(8H)-one) nucleobase pairs on the structural parameters of duplex DNA. nucleobase pairs follow standard rules for Watson-Crick base pairing but have rearranged hydrogen bonding donor and acceptor groups. Using the X-ray crystal structure as a starting point, we have modeled the motions of a DNA duplex built from a self-complementary oligonucleotide (5΄-CTTATPPPZZZATAAG-3΄) in water over a period of 50 μs and calculated DNA local parameters, step parameters, helix parameters, and major/minor groove widths to examine how the presence of multiple, consecutive nucleobase pairs might impact helical structure...
February 28, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334855/slc30a9-mutation-affecting-intracellular-zinc-homeostasis-causes-a-novel-cerebro-renal-syndrome
#11
Yonatan Perez, Zamir Shorer, Keren Liani-Leibson, Pauline Chabosseau, Rotem Kadir, Michael Volodarsky, Daniel Halperin, Shiran Barber-Zucker, Hanna Shalev, Ruth Schreiber, Libe Gradstein, Evgenia Gurevich, Raz Zarivach, Guy A Rutter, Daniel Landau, Ohad S Birk
A novel autosomal recessive cerebro-renal syndrome was identified in consanguineous Bedouin kindred: neurological deterioration was evident as of early age, progressing into severe intellectual disability, profound ataxia, camptocormia and oculomotor apraxia. Brain MRI was normal. Four of the six affected individuals also had early-onset nephropathy with features of tubulo-interstitial nephritis, hypertension and tendency for hyperkalemia, though none had rapid deterioration of renal function. Genome wide linkage analysis identified an ∼18 Mb disease-associated locus on chromosome 4 (maximal logarithm of odds score 4...
February 9, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28334819/comparative-analyses-of-the-thermodynamic-rna-binding-signatures-of-different-types-of-rna-recognition-motifs
#12
Brighton Samatanga, Antoine Cléry, Pierre Barraud, Frédéric H-T Allain, Ilian Jelesarov
RNA recognition motifs (RRMs) are structurally versatile domains important in regulation of alternative splicing. Structural mechanisms of sequence-specific recognition of single-stranded RNAs (ssRNAs) by RRMs are well understood. The thermodynamic strategies are however unclear. Therefore, we utilized microcalorimetry and semi-empirical analyses to comparatively analyze the cognate ssRNA binding thermodynamics of four different RRM domains, each with a different RNA binding mode. The different binding modes are: canonical binding to the β-sheet surface; canonical binding with involvement of N- and C-termini; binding to conserved loops; and binding to an α-helix...
February 23, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334658/extraction-of-the-3d-local-orientation-of-myocytes-in-human-cardiac-tissue-using-x-ray-phase-contrast-micro-tomography-and-multi-scale-analysis
#13
François Varray, Iulia Mirea, Max Langer, Françoise Peyrin, Laurent Fanton, Isabelle E Magnin
This paper presents a methodology to access the 3D local myocyte arrangements in fresh human post-mortem heart samples. We investigated the cardiac micro-structure at a high and isotropic resolution of 3.5 µm in three dimensions using X-ray phase micro-tomography at the European Synchrotron Radiation Facility. We then processed the reconstructed volumes to extract the 3D local orientation of the myocytes using a multi-scale approach with no segmentation. We created a simplified 3D model of tissue sample made of simulated myocytes with known size and orientations, to evaluate our orientation extraction method...
February 20, 2017: Medical Image Analysis
https://www.readbyqxmd.com/read/28334501/unravelling-a-direct-role-for-polysaccharide-%C3%AE-strands-in-the-higher-order-structure-of-physical-hydrogels
#14
Anja Rüther, Aurelien Forget, Anjan Roy, Carolina Carballo, Florian Mießmer, Rina K Dukor, Laurence A Nafie, Christian Johannessen, V Prasad Shastri, Steffen Lüdeke
The mechanical properties of agarose-derived hydrogels depend on the scaffolding of the polysaccharide network. To identify and quantify such higher order structure, we applied Raman optical activity (ROA)-a spectroscopic technique that is highly sensitive toward carbohydrates-on native agarose and chemically modified agarose in the gel phase for the first time. By spectral global fitting, we isolated features that change as a function of backbone carboxylation (28, 40, 50, 60, 80, and 93 %) from other features that remain unchanged...
March 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28333442/photoaffinity-ligand-for-the-inhalational-anesthetic-sevoflurane-allows-mechanistic-insight-into-potassium-channel-modulation
#15
Kellie A Woll, Wesley Peng, Qiansheng Liang, Lianteng Zhi, Jack A Jacobs, Lina Maciunas, Natarajan Bhanu, Benjamin A Garcia, Manuel Covarrubias, Patrick J Loll, William P Dailey, Roderic G Eckenhoff
Sevoflurane is a commonly used inhaled general anesthetic. Despite this, its mechanism of action remains largely elusive. Compared to other anesthetics, sevoflurane exhibits distinct functional activity. In particular, sevoflurane is a positive modulator of voltage-gated Shaker-related potassium channels (Kv1.x), which are key regulators of action potentials. Here, we report the synthesis and validation of azisevoflurane, a photoaffinity ligand for the direct identification of sevoflurane binding sites in the Kv1...
March 23, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28330183/purification-and-characterization-of-lipoxygenase-from-mung-bean-vigna-radiata-l-germinating-seedlings
#16
Raveendra Aanangi, Kasi Viswanath Kotapati, Bhagath Kumar Palaka, Thyagaraju Kedam, Nirmala Devi Kanika, Dinakara Rao Ampasala
This study reports purification and characterization of lipoxygenase protein from mung bean germinating seedlings. Lipoxygenases (LOXs) are key enzymes in seed germination. The purified mung bean LOX has resolved into two peaks by chromatofocusing, one has highest LOX activity with an isoelectric point of 5.84 and the other has lowest LOX activity with an isoelectric point of 5.52. The purified LOX has molecular mass of approximately 97 kDa and showed high activity with linoleic acid than linolenic acid and arachidonic acid...
June 2016: 3 Biotech
https://www.readbyqxmd.com/read/28330126/characterization-of-lignin-degrading-enzymes-ldes-from-a-dimorphic-novel-fungus-and-identification-of-products-of-enzymatic-breakdown-of-lignin
#17
Lipin Dev Mundur Sahadevan, Chandra Shekhar Misra, V Thankamani
Lignin is a major component of all plants, the degradation of which remains a major challenge to date owing to its recalcitrant nature. Several classes of fungi have been studied to carry out this process to some extent, but overall the process remains inefficient. We have isolated a novel alkalophilic dimorphic lignin-degrading Deuteromycete from soil, identified as "uncultured" and coded as MVI.2011. Supernatant from 12-h culture of MVI.2011 in optimized mineral medium containing lignin pH 9.0 was analysed for Lignin Peroxidase, Manganese Peroxidase and Laccase...
June 2016: 3 Biotech
https://www.readbyqxmd.com/read/28329594/perforating-gout-of-the-ear
#18
Leigh Sutton, Palak Parekh
Gout is the most common cause of inflammatory arthritis in men over 40 [1]. The prevalence of gout in the US is approximately 3.9%. Tophus is a characteristic sign of gout and results when monosodium urate deposits at the joint, skin, or cartilage. Tophi develop in 12-35% of patients who are diagnosed with gout [2]. We report a case of a 70-year-old man who was diagnosed with squamous cell carcinoma of the helix via shave biopsy. During Mohs micrographic surgery, a vigorous foreign-body reaction was noted. Review of the initial biopsy slides identified crystals with pseudoepitheliomatous hyperplasia (PEH) rendering a diagnosis of gout...
October 15, 2016: Dermatology Online Journal
https://www.readbyqxmd.com/read/28329249/acetylation-regulates-protein-stability-and-dna-binding-ability-of-hild-to-modulate-salmonella-typhimurium-virulence
#19
Yu Sang, Jie Ren, Ran Qin, Shuting Liu, Zhongli Cui, Sen Cheng, Xiaoyun Liu, Jie Lu, Jing Tao, Yu-Feng Yao
HilD, a dominant regulator of Salmonella pathogenicity island 1 (SPI-1), can be acetylated by acetyltransferase Pat in Salmonella Typhimurium, and the acetylation is beneficial to its stability. However, the underlying mechanism of HilD stability regulated by acetylation is not clear. We show here that lysine 297 (K297) located in the helix-turn-helix motif, can be acetylated by Pat. Acetylation of K297 increases HilD stability, but reduces its DNA-binding affinity. In turn, the deacetylated K297 enhances the DNA-binding ability, but decreases HilD stability...
February 24, 2017: Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28328501/monte-carlo-simulations-of-diffusion-weighted-mri-in-myocardium-validation-and-sensitivity-analysis
#20
Joanne Bates, Darryl McClymont, Irvin Teh, Peter Kohl, Jurgen Schneider, Vicente Grau
A model of cardiac microstructure and diffusion MRI is presented, and compared with experimental data from ex vivo rat hearts. The model includes a simplified representation of individual cells, with physiologically correct cell size and orientation, as well as intra- to extracellular volume ratio. Diffusion MRI is simulated using a Monte Carlo model and realistic MRI sequences. The results show good correspondence between the simulated and experimental MRI signals. Similar patterns are observed in the eigenvalues of the diffusion tensor, the mean diffusivity (MD) and the fractional anisotropy (FA)...
March 10, 2017: IEEE Transactions on Medical Imaging
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