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Lu Xu, Gordon Bosiljevac, Kyle Yu, Yi Y Zuo
Langmuir monolayer self-assembled at the air-water interface represents an excellent model for studying phase transition and lipid polymorphism in two dimensions. Compared to numerous studies of phospholipid phase transitions induced by isothermal compression, there are very scarce reports on two-dimensional phase transitions induced by isobaric heating. This is mainly due to technical difficulties of continuously regulating temperature variations while maintaining a constant surface pressure in a classical Langmuir-type film balance...
March 22, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Emma Langella, Martina Buonanno, Daniela Vullo, Nina Dathan, Marilisa Leone, Claudiu T Supuran, Giuseppina De Simone, Simona Maria Monti
Human carbonic anhydrase IX (hCA IX) is a tumour-associated enzyme present in a limited number of normal tissues, but overexpressed in several malignant human tumours. It is a transmembrane protein, where the extracellular region consists of a greatly investigated catalytic CA domain and a much less investigated proteoglycan-like (PG) domain. Considering its important role in tumour biology, here, we report for the first time the full characterization of the PG domain, providing insights into its structural and functional features...
March 21, 2018: Cellular and Molecular Life Sciences: CMLS
Javier Cervera, José A Manzanares, Salvador Mafe
Genetic networks operate in the presence of local heterogeneities in single-cell transcription and translation rates. Bioelectrical networks and spatio-temporal maps of cell electric potentials can influence multicellular ensembles. Could cell-cell bioelectrical interactions mediated by intercellular gap junctions contribute to the stabilization of multicellular states against local genetic heterogeneities? We theoretically analyze this question on the basis of two well-established experimental facts: (i) the membrane potential is a reliable read-out of the single-cell electrical state and (ii) when the cells are coupled together, their individual cell potentials can be influenced by ensemble-averaged electrical potentials...
March 22, 2018: Physical Chemistry Chemical Physics: PCCP
Kornelius Zeth, Ulrich Zachariae
Mitochondria are evolutionarily related to Gram-negative bacteria and both comprise two membrane systems with strongly differing protein composition. The major protein in the outer membrane of mitochondria is the voltage-dependent anion channel (VDAC), which mediates signal transmission across the outer membrane but also the exchange of metabolites, most importantly ADP and ATP. More than 30 years after its discovery three identical high-resolution structures were determined in 2008. These structures show a 19-stranded anti-parallel beta-barrel with an N-terminal helix located inside...
2018: Frontiers in Physiology
Styliani Vakrou, Ryuya Fukunaga, D Brian Foster, Lars Sorensen, Yamin Liu, Yufan Guan, Kirubel Woldemichael, Roberto Pineda-Reyes, Ting Liu, Jill C Tardiff, Leslie A Leinwand, Carlo G Tocchetti, Theodore P Abraham, Brian O'Rourke, Miguel A Aon, M Roselle Abraham
Hypertrophic cardiomyopathy (HCM) stems from mutations in sarcomeric proteins that elicit distinct biophysical sequelae, which in turn may yield radically different intracellular signaling and molecular pathologic profiles. These signaling events remain largely unaddressed by clinical trials that have selected patients based on clinical HCM diagnosis, irrespective of genotype. In this study, we determined how two mouse models of HCM differ, with respect to cellular/mitochondrial function and molecular biosignatures, at an early stage of disease...
March 22, 2018: JCI Insight
Yukihiro Nakamura, Maria Reva, David A DiGregorio
The timing and probability of synaptic vesicle fusion from presynaptic terminals is governed by the strength of coupling between voltage-gated Ca2+ channels (VGCCs) and Ca2+ sensors for exocytosis. This VGCC-sensor coupling distance can be estimated from the fractional block of vesicular release by exogenous Ca2+ chelators. However, estimates of this distance can depend on many biophysical factors, whose contributions have not been thoroughly explored. Using numerical simulations of Ca2+ reaction and diffusion, as well as vesicular release, we examined the contributions of conductance, density, and open duration of VGCCs, as well as the influence of endogenous Ca2+ buffers on the inhibition of exocytosis by EGTA...
March 21, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Isaac Fernández-Gómez, Marquiza Sablón-Carrazana, Alberto Bencomo-Martínez, Guadalupe Domínguez, Reyna Lara-Martínez, Nelly F Altamirano-Bustamante, Luis Felipe Jiménez-García, Karina Pasten-Hidalgo, Rosa Angélica Castillo-Rodríguez, Perla Altamirano, Suchitil Rivera Marrero, Cristina Revilla-Monsalve, Peter Valdés-Sosa, Fabio Salamanca-Gómez, Eulalia Garrido-Magaña, Chryslaine Rodríguez-Tanty, Myriam M Altamirano-Bustamante
Human islet amyloid peptide (hIAPP1-37 ) aggregation is an early step in Diabetes Mellitus. We aimed to evaluate a family of pharmaco-chaperones to act as modulators that provide dynamic interventions and the multi-target capacity (native state, cytotoxic oligomers, protofilaments and fibrils of hIAPP1-37 ) required to meet the treatment challenges of diabetes. We used a cross-functional approach that combines in silico and in vitro biochemical and biophysical methods to study the hIAPP1-37 aggregation-oligomerization process as to reveal novel potential anti-diabetic drugs...
March 19, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Caterina Monini, Micaela Cunha, Etienne Testa, Michaёl Beuve
NanOx is a new biophysical model that aims at predicting the biological effect of ions in the context of hadron therapy. It integrates the fully-stochastic nature of ionizing radiation both at micrometric and nanometric scales and also takes into account the production and diffusion of reactive chemical species. In order to further characterize the new framework, we discuss the meaning and relevance of most of the NanOx parameters by evaluating their influence on the linear-quadratic coefficient α and on the dose deposited to achieve 10% or 1% of cell survival, D 10 % or D 1 % , as a function of LET...
March 21, 2018: Cancers
Jeremy C Smith, Pan Tan, Loukas Petridis, Liang Hong
Dynamic neutron scattering directly probes motions in biological systems on femtosecond to microsecond timescales. When combined with molecular dynamics simulation and normal mode analysis, detailed descriptions of the forms and frequencies of motions can be derived. We examine vibrations in proteins, the temperature dependence of protein motions, and concepts describing the rich variety of motions detectable using neutrons in biological systems at physiological temperatures. New techniques for deriving information on collective motions using coherent scattering are also reviewed...
March 21, 2018: Annual Review of Biophysics
Ekta Makhija, Anna Jagielska, Lena Zhu, Alexander C Bost, William Ong, Sing Y Chew, G V Shivashankar, Krystyn J Van Vliet
Mechanical and physical stimuli including material stiffness and topography or applied mechanical strain have been demonstrated to modulate differentiation of glial progenitor and neural stem cells. Recent studies probing such mechanotransduction in oligodendrocytes have focused chiefly on the biomolecular components. However, the cell-level biophysical changes associated with such responses remain largely unknown. Here, we explored mechanotransduction in oligodendrocyte progenitor cells (OPCs) during the first 48 h of differentiation induction by quantifying the biophysical state in terms of nuclear dynamics, cytoskeleton organization, and cell migration...
2018: Frontiers in Cellular Neuroscience
Vasudha C Shukla, Tai-Rong Kuang, Abirami Senthilvelan, Natalia Higuita-Castro, Silvia Duarte-Sanmiguel, Samir N Ghadiali, Daniel Gallego-Perez
Recent cancer research has more strongly emphasized the biophysical aspects of tumor development, progression, and microenvironment. In addition to genetic modifications and mutations in cancer cells, it is now well accepted that the physical properties of cancer cells such as stiffness, electrical impedance, and refractive index vary with tumor progression and can identify a malignant phenotype. Moreover, cancer heterogeneity renders population-based characterization techniques inadequate, as individual cellular features are lost in the average...
March 17, 2018: Trends in Biotechnology
Himanshu Pandey, Farheen Fatma, Shivraj M Yabaji, Meera Kumari, Sarita Tripathi, Kanchan Srivastava, Dinesh K Tripathi, Surya Kant, Kishore K Srivastava, Ashish Arora
The ESAT-6 family proteins of Mycobacterium tuberculosis are regarded as the key mediators in mycobacterial virulence and are largely considered as antigens that can improve TB vaccines and diagnostics. We have characterized Rv3444c and Rv3445c proteins of the ESX-4 system of ESAT-6 family of M. tuberculosis H37Rv, and have experimentally established that these two proteins interact to form a heterodimeric complex. Complex formation resulted in induction of α-helical conformation and stability against chemical denaturation...
March 2018: Tuberculosis
Junghyun L Suh, Brian Watts, Jacob I Stuckey, Jacqueline L Norris-Drouin, Stephanie H Cholensky, Bradley M Dickson, Yi An, Sebastian Mathea, Eidarus Salah, Stefan Knapp, Abid Khan, Alexander T Adams, Brian D Strahl, Cari A Sagum, Mark T Bedford, Lindsey I James, Dmitri B Kireev, Stephen V Frye
Multivalent binding is an efficient means to enhance the affinity and specificity of chemical probes targeting multi-domain proteins in order to study their function and role in disease. While the theory of multivalent binding is straightforward, physical and structural characterization of bivalent binding encounters multiple technical difficulties. We present a case study where a combination of experimental techniques and computational simulations was used to comprehensively characterize the binding and structure-affinity relationships for a series of Bromosporine-based bivalent bromodomain ligands with a bivalent protein, Transcription Initiation Factor TFIID subunit 1 (TAF1)...
March 20, 2018: Biochemistry
Kolla Rajasekhar, Kapilkumar Mehta, Thimmaiah Govindaraju
Amyloid beta (Aβ) aggregation is the key trait responsible for the pathological devastation caused by Alzheimer's disease (AD). Among the various pathways of multifaceted toxicity exhibited by Aβ aggregates in neuronal cells, generation of reactive oxygen species (ROS) by Aβ-CuII complex and mitochondrial damage are prominent. Aβ interferes with mitochondrial transport channels, causing mitochondrial dysfunction. Herein, we present nontoxic hybrid multifunctional modulators (HMMs, TGR86-88) developed by integrating the structural and functional features of the metal chelating aggregation modulator, clioquinol (Clq) and the antioxidant epigallocatechin gallate (EGCG)...
March 20, 2018: ACS Chemical Neuroscience
Ruoxing Lei, Jessica P Lee, Matthew B Francis, Sanjay Kumar
Intrinsically disordered proteins (IDPs) play central roles in numerous cellular processes. While IDP structure and function are often regulated by multisite phosphorylation, the biophysical mechanisms linking these post-translational modifications to IDP structure remain elusive. For example, the intrinsically disordered C-terminal sidearm domain of the neurofilament heavy subunit (NFH-SA) forms a dense brush along axonal NF backbones and is subject to extensive serine phosphorylation. Yet, biophysical insight into the relationship between phosphorylation and structure has been limited by the lack of paradigms in which NF brush conformational responses can be measured in the setting of controlled phosphorylation...
March 20, 2018: Biochemistry
Cathryn Clarke Murray, Janson Wong, Gerald G Singh, Megan Mach, Jackie Lerner, Bernardo Ranieri, Guillaume Peterson St-Laurent, Alice Guimaraes, Kai M A Chan
Environmental assessment is the process that decision-makers rely on to predict, evaluate, and prevent biophysical, social, and economic impacts of potential project developments. The determination of significance in environmental assessment is central to environmental management in many nations. We reviewed ten recent environmental impact assessments from British Columbia, Canada and systematically reviewed and scored significance determination and the approaches used by assessors, the use of thresholds in significance determination, threshold exceedances, and the outcomes...
March 19, 2018: Environmental Management
Julie Eberle Davis, Ravi Kumar Gundampati, Srinivas Jayanthi, Joshua Anderson, Abigail Pickhardt, Bhanu Prasanth Koppolu, David A Zaharoff, Thallapuranam Krishnaswamy Suresh Kumar
Acidic human fibroblast growth factor (hFGF1) plays a key role in cell growth and proliferation. Activation of the cell surface FGF receptor is believed to involve the glycosaminoglycan, heparin. However, the exact role of heparin is a subject of considerable debate. In this context, in this study, the correlation between heparin binding affinity and cell proliferation activity of hFGF1 is examined by extending the heparin binding pocket through selective engineering via charge reversal mutations (D82R, D84R and D82R/D84R)...
March 2018: Biochemistry and Biophysics Reports
Carla Caballero, Sejal Mistry, Joe Vero, Elizabeth B Torres
The variability inherently present in biophysical data is partly contributed by disparate sampling resolutions across instrumentations. This poses a potential problem for statistical inference using pooled data in open access repositories. Such repositories combine data collected from multiple research sites using variable sampling resolutions. One example is the Autism Brain Imaging Data Exchange repository containing thousands of imaging and demographic records from participants in the spectrum of autism and age-matched neurotypical controls...
2018: Frontiers in Integrative Neuroscience
Siddhant Bhoir, Althaf Shaik, Vijay Thiruvenkatam, Sivapriya Kirubakaran
Human Tousled-like kinases (TLKs) are highly conserved serine/threonine protein kinases responsible for cell proliferation, DNA repair, and genome surveillance. Their possible involvement in cancer via efficient DNA repair mechanisms have made them clinically relevant molecular targets for anticancer therapy. Innovative approaches in chemical biology have played a key role in validating the importance of kinases as molecular targets. However, the detailed understanding of the protein structure and the mechanisms of protein-drug interaction through biochemical and biophysical techniques demands a method for the production of an active protein of exceptional stability and purity on a large scale...
March 19, 2018: Scientific Reports
Xiaofan Jin, Ingmar H Riedel-Kruse
Bacterial biofilms represent a promising opportunity for engineering of microbial communities. However, our ability to control spatial structure in biofilms remains limited. Here we engineer Escherichia coli with a light-activated transcriptional promoter (pDawn) to optically regulate expression of an adhesin gene (Ag43). When illuminated with patterned blue light, long-term viable biofilms with spatial resolution down to 25 μm can be formed on a variety of substrates and inside enclosed culture chambers without the need for surface pretreatment...
March 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
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