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Molecular BioSystems

M Baranek, A Belter, M Z Naskręt-Barciszewska, M Stobiecki, W T Markiewicz, J Barciszewski
The essential idea of regenerative medicine is to fix or replace tissues or organs with alive and patient-specific implants. Pluripotent stem cells are able to indefinitely self-renew and differentiate into all cell types of the body which makes them a potent substantial player in regenerative medicine. The easily accessible source of induced pluripotent stem cells may allow obtaining and cultivating tissues in vitro. Reprogramming refers to regression of mature cells to its initial pluripotent state. One of the approaches affecting pluripotency is the usage of low molecular mass compounds that can modulate enzymes and receptors leading to the formation of pluripotent stem cells (iPSCs)...
December 5, 2016: Molecular BioSystems
Jamal Adiban, Yousef Jamali, Hashem Rafii-Tabar
Activation of voltage-gated calcium channels by action potentials leads to the influx of Ca(2+) ions. In this study, the ion permeation characteristics in bacterial voltage-gated calcium (CaVAb) channels were investigated using molecular dynamics simulations. Furthermore, the potential of mean force (PMF) calculations was evaluated to determine the free energy profile for the permeation of cations (Ca(2+) and Na(+)) and anions (Cl(-)) in the CaVAb channel. The results showed that both Ca(2+) and Na(+) cations experienced a deep energy well, while the Cl(-) anion experienced a relatively high energy barrier at the center of the selectivity filter (site 2)...
December 5, 2016: Molecular BioSystems
Bikash Ranjan Sahoo, Toshimichi Fujiwara
Understanding the downstream signaling mechanism of sensory rhodopsin and its cognate transducer complex (srII-htrII) has long been a challenge in the field of photoreceptor research. Here, an integration of all-atom and coarse-grained (CG) molecular dynamics (MD) simulations in different srII-htrII complex states is carried out. It is shown that the cytoplasmic four-helix HAMP dimer gives rise to a gear-box model interaction with discrete hydrophobic packing in Natronomonas pharaonis (Np). Structural analysis in all-atom and CG-MD reveals a stable conformational state in the physiological environment (323 K and 1...
November 30, 2016: Molecular BioSystems
Tianlei Zhang, Aihua Zhang, Shi Qiu, Hui Sun, Ying Han, Yu Guan, Xijun Wang
Alcohol-induced liver injury (ALD) shows obvious metabolic disorders, categorized by a wide range of metabolite abnormalities. High-throughput metabolomics technology appears to be an appropriate solution. In this study, a urine metabolic profile was assessed using a UPLC-Q-TOF/HDMS (liquid chromatography coupled to high resolution mass spectrometry) approach to investigate the underlying molecular mechanisms of ALD and the therapeutic effect of geniposide. The endogenous low-molecular-weight metabolites in the mouse model of ALD were observed and 48 specific biomarkers were identified...
November 29, 2016: Molecular BioSystems
Sayem Miah, Charles A S Banks, Mark K Adams, Laurence Florens, Kiven E Lukong, Michael P Washburn
Understanding the complexity of cancer biology requires extensive information about the cancer proteome over the course of the disease. The recent advances in mass spectrometry-based proteomics technologies have led to the accumulation of an incredible amount of such proteomic information. This information allows us to identify protein signatures or protein biomarkers, which can be used to improve cancer diagnosis, prognosis and treatment. For example, mass spectrometry-based proteomics has been used in breast cancer research for over two decades to elucidate protein function...
November 28, 2016: Molecular BioSystems
Yury O Nunez Lopez, Gabriella Garufi, Attila A Seyhan
Today obesity and type 2 diabetes (T2D) have both reached epidemic proportions. However, our current understanding of the primary mechanisms leading to these diseases is still limited due to the complex multifactorial nature of the underlying phenomena. We hypothesize that the levels of specific cytokines and miRNAs vary across the diabetes spectrum and unique signatures associated with them may serve as early biomarkers of the disease and provide insights into respective pathogenetic mechanisms. In this study, we measured the circulating levels of cytokines and microRNAs (miRNAs) in lean and obese humans with prediabetes (n = 21), T2D (n = 17), and healthy controls (n = 20) (ORIGINS trial, NCT02226640)...
November 21, 2016: Molecular BioSystems
Le Ou-Yang, Hong Yan, Xiao-Fei Zhang
Exploring how the structure of a gene regulatory network differs between two different disease states is fundamental for understanding the biological mechanisms behind disease development and progression. Recently, with rapid advances in microarray technologies, gene expression profiles of the same patients can be collected from multiple microarray platforms. However, previous differential network analysis methods were usually developed based on a single type of platform, which could not utilize the common information shared across different platforms...
November 21, 2016: Molecular BioSystems
Jennifer A E Payne, Melanie Schoppet, Mathias Henning Hansen, Max J Cryle
The biosynthesis of complex natural products by non-ribosomal peptide synthetases (NRPSs) and the related polyketide synthases (PKSs) represents a major source of important bioactive compounds. These large, multi-domain machineries are able to produce a fascinating range of molecules due to the nature of their modular architectures, which allows natural products to be assembled and tailored in a modular, step-wise fashion. In recent years there has been significant progress in characterising the important domains and underlying mechanisms of non-ribosomal peptide synthesis...
November 17, 2016: Molecular BioSystems
L Dorosh, M Stepanova
Aggregation of amyloid β (Aβ) peptide is implicated in fatal Alzheimer's disease, for which no cure is available. Understanding the mechanisms responsible for this aggregation is required in order for therapies to be developed. In an effort to better understand the molecular mechanisms involved in spontaneous aggregation of Aβ peptide, extensive molecular dynamics simulations are reported, and the results are analyzed through a combination of structural biology tools and a novel essential collective dynamics method...
November 15, 2016: Molecular BioSystems
Jin-Mai Zhang, Cheng Jiang, Wei Ye, Ray Luo, Hai-Feng Chen
Riboswitches are cis-acting genetic control elements. Due to their fundamental importance in bacteria gene regulation, they have been proposed as antibacterial drug targets. Tetrahydrofolate (THF) is an essential cofactor of one-carbon transfer reactions and downregulates the expression of downstream genes. However, information on how to transfer from the binding site of THF to the expression platform is still unavailable. Herein, a nucleotide/nucleotide dynamics correlation network based on an all-atom molecular dynamic simulation was used to reveal the regulation mechanism of a THF-sensing riboswitch...
November 14, 2016: Molecular BioSystems
Ashutosh Srivastava, Somdatta Sinha
Anthranilate synthase (AS) is the first branch node enzyme that catalyzes the conversion of chorismate to anthranilate in the high energy-consuming tryptophan biosynthetic pathway in Serratia marcescens. AS, with an allosterically-bound inhibitor (tryptophan), shows complete inhibition in its catalytic function, but the inhibitor-bound structure is very similar to that of the substrate-bound AS. Even though the reaction mechanisms of several chorismate-utilizing enzymes are known, the unusual structure-function relationship in catalysis and allosteric inhibition of AS by tryptophan, with an insignificant change in structure, remains elusive...
November 11, 2016: Molecular BioSystems
Nikolas Ferreira Dos Santos Paparidis, Maxwell Castro Durvale, Fernanda Canduri
CDK9 is a prominent member of the transcriptional CDKs subfamily, a group of kinases whose function is to control the primary steps of mRNA synthesis and processing by eukaryotic RNA polymerase II. As a cyclin-dependent kinase, CDK9 activation in vivo depends upon its association with T-type cyclins to assemble the positive transcription elongation factor (P-TEFb). Although CDK9/P-TEFb phosphorylates the C-terminal domain of RNAP II in the same positions targeted by CDK7 (TFIIH) and CDK8 (Mediator), the former does not participate in the transcription initiation, but rather plays a unique role by driving the polymerase to productive elongation...
November 11, 2016: Molecular BioSystems
Vladimir N Uversky, Elrashdy M Redwan
Erythropoietin (Epo) is a heavily glycosylated protein, with its main function being related to erythropoiesis, where it controls red blood cell production via interaction with the Epo receptor (EpoR). It also plays a number of important roles in various hormonal, growth factor, and cytokine pathways. These roles are defined by Epo partners, such as the homodimeric (EpoR)2 receptor, the heterodimeric EpoR/βCR receptor and hypoxia inducing factor (HIF). Although the main structural features of both Epo and EpoR are conserved in vertebrates, the secretion sites of Epo in mammals are different from those in other vertebrates...
November 11, 2016: Molecular BioSystems
Heli Tan, Tuoqi Liu, Jiajun Zhang, Tianshou Zhou
Chromosomal regions are often dynamically modified by histones, leading to the uncertainty of nucleosome positions. Experiments have provided evidence for this randomness, but it is unclear how it impacts epigenetic heritability. Here, by analyzing a mechanic model at the molecular level, which considers three representative types of nucleosomes (unmodified, methylated, and acetylated) and dynamic nucleosome modifications, we find that in contrast to the equidistance partition of nucleosomes, random partition can significantly enhance heritable bistability...
November 11, 2016: Molecular BioSystems
Fei Ye, Jiahui Li, Cai-Guang Yang
The global spread of antibiotic resistance among important human pathogens emphasizes the need to find new antibacterial drugs with a novel mode of action. The ClpP protease has been shown to demonstrate its pivotal importance to both the survival and the virulence of pathogenic bacteria during host infection. Deregulating ClpP activity either through overactivation or inhibition could lead to antibacterial activity, declaiming the dual molecular mechanism for small-molecule modulation. Recently, natural products acyldepsipeptides (ADEPs) have been identified as a new class of antibiotics that activate ClpP to a dysfunctional state in the absence of cognate ATPases...
November 10, 2016: Molecular BioSystems
Kunihiko Morihiro, Yuuya Kasahara, Satoshi Obika
Xeno nucleic acids (XNAs) are a group of chemically modified nucleic acid analogues that have been applied to various biological technologies such as antisense oligonucleotides, siRNAs and aptamers.
November 9, 2016: Molecular BioSystems
Faraz K Mardakheh, Heba Z Sailem, Sandra Kümper, Christopher J Tape, Ryan R McCully, Angela Paul, Sara Anjomani-Virmouni, Claus Jørgensen, George Poulogiannis, Christopher J Marshall, Chris Bakal
Localisation and protein function are intimately linked in eukaryotes, as proteins are localised to specific compartments where they come into proximity of other functionally relevant proteins. Significant co-localisation of two proteins can therefore be indicative of their functional association. We here present COLA, a proteomics based strategy coupled with a bioinformatics framework to detect protein-protein co-localisations on a global scale. COLA reveals functional interactions by matching proteins with significant similarity in their subcellular localisation signatures...
November 8, 2016: Molecular BioSystems
Yiqing Zhou, Weichao Li, Mingli Wang, Xixi Zhang, Haibing Zhang, Xiaofeng Tong, Youli Xiao
Celastrol, isolated from the traditional Chinese medicinal herb Tripterygium wilfordii Hook. f. (Thunder God's Vine), has been used to treat cancer, chronic inflammatory, autoimmune and other human diseases. However, to date, the protein targets and the mechanism of action of celastrol have remained elusive. In this study, we find that celastrol can react with protein thiols in a unique covalent and reversible manner, while protein denaturing disrupts the interaction. Through a competitive chemoproteomics approach utilizing a cysteine-targeting activity-based probe, we report the proteome-wide quantitative profiling of cellular targets of celastrol in human cervical cancer HeLa cells...
November 7, 2016: Molecular BioSystems
Shu-Ichi Nakano, Naoki Sugimoto
Molecular interactions and reactions in living cells occur with high concentrations of background molecules and ions. Many research studies have shown that intracellular molecules have characteristics different from those obtained using simple aqueous solutions. To better understand the behavior of biomolecules in intracellular environments, biophysical experiments were conducted under cell-mimicking conditions in a test tube. It has been shown that the molecular environments at the physiological level of macromolecular crowding, spatial confinement, water activity and dielectric constant, have significant effects on the interactions of DNA and RNA for hybridization, higher-order folding, and catalytic activity...
November 7, 2016: Molecular BioSystems
C F Baez, V A Barel, A M T de Souza, C R Rodrigues, R B Varella, N Cirauqui
Zika virus (ZIKV) is an emergent arbovirus that has attracted attention in the last year as a possible causative agent of congenital malformation; it shows a remarkably increased microcephaly risk during otherwise healthy pregnancies. We present here an analysis of all ZIKV sequences available in Genbank up to April 2016, studying the mutations in the whole polyprotein and their possible structural implications for the proteins E, NS1, NS3 and NS5. This study suggests that microcephaly is not a consequence of any particular amino acid substitution but, conceivably, is a feature of ZIKV itself...
November 2, 2016: Molecular BioSystems
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