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  1. Article ; Online: Elastic network modeling of cellular networks unveils sensor and effector genes that control information flow.

    Omer Acar / She Zhang / Ivet Bahar / Anne-Ruxandra Carvunis

    PLoS Computational Biology, Vol 18, Iss 5, p e

    2022  Volume 1010181

    Abstract: The high-level organization of the cell is embedded in indirect relationships that connect distinct cellular processes. Existing computational approaches for detecting indirect relationships between genes typically consist of propagating abstract ... ...

    Abstract The high-level organization of the cell is embedded in indirect relationships that connect distinct cellular processes. Existing computational approaches for detecting indirect relationships between genes typically consist of propagating abstract information through network representations of the cell. However, the selection of genes to serve as the source of propagation is inherently biased by prior knowledge. Here, we sought to derive an unbiased view of the high-level organization of the cell by identifying the genes that propagate and receive information most effectively in the cell, and the indirect relationships between these genes. To this aim, we adapted a perturbation-response scanning strategy initially developed for identifying allosteric interactions within proteins. We deployed this strategy onto an elastic network model of the yeast genetic interaction profile similarity network. This network revealed a superior propensity for information propagation relative to simulated networks with similar topology. Perturbation-response scanning identified the major distributors and receivers of information in the network, named effector and sensor genes, respectively. Effectors formed dense clusters centrally integrated into the network, whereas sensors formed loosely connected antenna-shaped clusters and contained genes with previously characterized involvement in signal transduction. We propose that indirect relationships between effector and sensor clusters represent major paths of information flow between distinct cellular processes. Genetic similarity networks for fission yeast and human displayed similarly strong propensities for information propagation and clusters of effector and sensor genes, suggesting that the global architecture enabling indirect relationships is evolutionarily conserved across species. Our results demonstrate that elastic network modeling of cellular networks constitutes a promising strategy to probe the high-level organization and cooperativity in the cell.
    Keywords Biology (General) ; QH301-705.5
    Subject code 006
    Language English
    Publishing date 2022-05-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Editorial

    Claire Colas / Ivet Bahar / Lei Shi / Josep Font Sadurni

    Frontiers in Chemistry, Vol

    Targeting Membrane Proteins: Structure-Function-Dynamics Relationships

    2022  Volume 10

    Keywords membrane proteins ; drug targets ; structure ; function ; dynamics ; Chemistry ; QD1-999
    Language English
    Publishing date 2022-03-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Complementary computational and experimental evaluation of missense variants in the ROMK potassium channel.

    Luca Ponzoni / Nga H Nguyen / Ivet Bahar / Jeffrey L Brodsky

    PLoS Computational Biology, Vol 16, Iss 4, p e

    2020  Volume 1007749

    Abstract: The renal outer medullary potassium (ROMK) channel is essential for potassium transport in the kidney, and its dysfunction is associated with a salt-wasting disorder known as Bartter syndrome. Despite its physiological significance, we lack a mechanistic ...

    Abstract The renal outer medullary potassium (ROMK) channel is essential for potassium transport in the kidney, and its dysfunction is associated with a salt-wasting disorder known as Bartter syndrome. Despite its physiological significance, we lack a mechanistic understanding of the molecular defects in ROMK underlying most Bartter syndrome-associated mutations. To this end, we employed a ROMK-dependent yeast growth assay and tested single amino acid variants selected by a series of computational tools representative of different approaches to predict each variants' pathogenicity. In one approach, we used in silico saturation mutagenesis, i.e. the scanning of all possible single amino acid substitutions at all sequence positions to estimate their impact on function, and then employed a new machine learning classifier known as Rhapsody. We also used two additional tools, EVmutation and Polyphen-2, which permitted us to make consensus predictions on the pathogenicity of single amino acid variants in ROMK. Experimental tests performed for selected mutants in different classes validated the vast majority of our predictions and provided insights into variants implicated in ROMK dysfunction. On a broader scope, our analysis suggests that consolidation of data from complementary computational approaches provides an improved and facile method to predict the severity of an amino acid substitution and may help accelerate the identification of disease-causing mutations in any protein.
    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2020-04-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Coupled mixed model for joint genetic analysis of complex disorders with two independently collected data sets

    Haohan Wang / Fen Pei / Michael M. Vanyukov / Ivet Bahar / Wei Wu / Eric P. Xing

    BMC Bioinformatics, Vol 22, Iss 1, Pp 1-

    2021  Volume 14

    Abstract: Abstract Background In the last decade, Genome-wide Association studies (GWASs) have contributed to decoding the human genome by uncovering many genetic variations associated with various diseases. Many follow-up investigations involve joint analysis of ... ...

    Abstract Abstract Background In the last decade, Genome-wide Association studies (GWASs) have contributed to decoding the human genome by uncovering many genetic variations associated with various diseases. Many follow-up investigations involve joint analysis of multiple independently generated GWAS data sets. While most of the computational approaches developed for joint analysis are based on summary statistics, the joint analysis based on individual-level data with consideration of confounding factors remains to be a challenge. Results In this study, we propose a method, called Coupled Mixed Model (CMM), that enables a joint GWAS analysis on two independently collected sets of GWAS data with different phenotypes. The CMM method does not require the data sets to have the same phenotypes as it aims to infer the unknown phenotypes using a set of multivariate sparse mixed models. Moreover, CMM addresses the confounding variables due to population stratification, family structures, and cryptic relatedness, as well as those arising during data collection such as batch effects that frequently appear in joint genetic studies. We evaluate the performance of CMM using simulation experiments. In real data analysis, we illustrate the utility of CMM by an application to evaluating common genetic associations for Alzheimer’s disease and substance use disorder using datasets independently collected for the two complex human disorders. Comparison of the results with those from previous experiments and analyses supports the utility of our method and provides new insights into the diseases. The software is available at https://github.com/HaohanWang/CMM .
    Keywords Joint analysis ; Mixed model ; Deconfounding ; Computer applications to medicine. Medical informatics ; R858-859.7 ; Biology (General) ; QH301-705.5
    Subject code 310
    Language English
    Publishing date 2021-02-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Functional Characterization of the Dopaminergic Psychostimulant Sydnocarb as an Allosteric Modulator of the Human Dopamine Transporter

    Shaili Aggarwal / Mary Hongying Cheng / Joseph M. Salvino / Ivet Bahar / Ole Valente Mortensen

    Biomedicines, Vol 9, Iss 634, p

    2021  Volume 634

    Abstract: The dopamine transporter (DAT) serves a critical role in controlling dopamine (DA)-mediated neurotransmission by regulating the clearance of DA from the synapse and extrasynaptic regions and thereby modulating DA action at postsynaptic DA receptors. ... ...

    Abstract The dopamine transporter (DAT) serves a critical role in controlling dopamine (DA)-mediated neurotransmission by regulating the clearance of DA from the synapse and extrasynaptic regions and thereby modulating DA action at postsynaptic DA receptors. Major drugs of abuse such as amphetamine and cocaine interact with DATs to alter their actions resulting in an enhancement in extracellular DA concentrations. We previously identified a novel allosteric site in the DAT and the related human serotonin transporter that lies outside the central orthosteric substrate- and cocaine-binding pocket. Here, we demonstrate that the dopaminergic psychostimulant sydnocarb is a ligand of this novel allosteric site. We identified the molecular determinants of the interaction between sydnocarb and DAT at the allosteric site using molecular dynamics simulations. Biochemical-substituted cysteine scanning accessibility experiments have supported the computational predictions by demonstrating the occurrence of specific interactions between sydnocarb and amino acids within the allosteric site. Functional dopamine uptake studies have further shown that sydnocarb is a noncompetitive inhibitor of DAT in accord with the involvement of a site different from the orthosteric site in binding this psychostimulant. Finally, DA uptake studies also demonstrate that sydnocarb affects the interaction of DAT with both cocaine and amphetamine. In summary, these studies further strengthen the prospect that allosteric modulation of DAT activity could have therapeutic potential.
    Keywords dopamine transporter ; allosteric modulation ; transport activity ; Biology (General) ; QH301-705.5
    Subject code 500
    Language English
    Publishing date 2021-06-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: HiDeF

    Fan Zheng / She Zhang / Christopher Churas / Dexter Pratt / Ivet Bahar / Trey Ideker

    Genome Biology, Vol 22, Iss 1, Pp 1-

    identifying persistent structures in multiscale ‘omics data

    2021  Volume 15

    Abstract: Abstract In any ‘omics study, the scale of analysis can dramatically affect the outcome. For instance, when clustering single-cell transcriptomes, is the analysis tuned to discover broad or specific cell types? Likewise, protein communities revealed from ...

    Abstract Abstract In any ‘omics study, the scale of analysis can dramatically affect the outcome. For instance, when clustering single-cell transcriptomes, is the analysis tuned to discover broad or specific cell types? Likewise, protein communities revealed from protein networks can vary widely in sizes depending on the method. Here, we use the concept of persistent homology, drawn from mathematical topology, to identify robust structures in data at all scales simultaneously. Application to mouse single-cell transcriptomes significantly expands the catalog of identified cell types, while analysis of SARS-COV-2 protein interactions suggests hijacking of WNT. The method, HiDeF, is available via Python and Cytoscape.
    Keywords Systems biology ; Multiscale ; Persistent homology ; Community detection ; Resolution ; Single-cell clustering ; Biology (General) ; QH301-705.5 ; Genetics ; QH426-470
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Impact of new variants on SARS-CoV-2 infectivity and neutralization

    Mary Hongying Cheng / James M. Krieger / Anupam Banerjee / Yufei Xiang / Burak Kaynak / Yi Shi / Moshe Arditi / Ivet Bahar

    iScience, Vol 25, Iss 3, Pp 103939- (2022)

    A molecular assessment of the alterations in the spike-host protein interactions

    2022  

    Abstract: Summary: The emergence of SARS-CoV-2 variants necessitates rational assessment of their impact on the recognition and neutralization of the virus by the host cell. We present a comparative analysis of the interactions of Alpha, Beta, Gamma, and Delta ... ...

    Abstract Summary: The emergence of SARS-CoV-2 variants necessitates rational assessment of their impact on the recognition and neutralization of the virus by the host cell. We present a comparative analysis of the interactions of Alpha, Beta, Gamma, and Delta variants with cognate molecules (ACE2 and/or furin), neutralizing nanobodies (Nbs), and monoclonal antibodies (mAbs) using in silico methods, in addition to Nb-binding assays. Our study elucidates the molecular origin of the ability of Beta and Delta variants to evade selected antibodies, such as REGN10933, LY-CoV555, B38, C105, or H11-H4, while being insensitive to others including REGN10987. Experiments confirm that nanobody Nb20 retains neutralizing activity against the Delta variant. The substitutions T478K and L452R in the Delta variant enhance associations with ACE2, whereas P681R promotes recognition by proteases, thus facilitating viral entry. The Ab-specific responses of variants highlight how full-atomic structure and dynamics analyses are required for assessing the response to newly emerging variants.
    Keywords Biological sciences ; Virology ; Structural biology ; Science ; Q
    Subject code 572
    Language English
    Publishing date 2022-03-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Complete mapping of substrate translocation highlights the role of LeuT N-terminal segment in regulating transport cycle.

    Mary Hongying Cheng / Ivet Bahar

    PLoS Computational Biology, Vol 10, Iss 10, p e

    2014  Volume 1003879

    Abstract: Neurotransmitter: sodium symporters (NSSs) regulate neuronal signal transmission by clearing excess neurotransmitters from the synapse, assisted by the co-transport of sodium ions. Extensive structural data have been collected in recent years for several ...

    Abstract Neurotransmitter: sodium symporters (NSSs) regulate neuronal signal transmission by clearing excess neurotransmitters from the synapse, assisted by the co-transport of sodium ions. Extensive structural data have been collected in recent years for several members of the NSS family, which opened the way to structure-based studies for a mechanistic understanding of substrate transport. Leucine transporter (LeuT), a bacterial orthologue, has been broadly adopted as a prototype in these studies. This goal has been elusive, however, due to the complex interplay of global and local events as well as missing structural data on LeuT N-terminal segment. We provide here for the first time a comprehensive description of the molecular events leading to substrate/Na+ release to the postsynaptic cell, including the structure and dynamics of the N-terminal segment using a combination of molecular simulations. Substrate and Na+-release follows an influx of water molecules into the substrate/Na+-binding pocket accompanied by concerted rearrangements of transmembrane helices. A redistribution of salt bridges and cation-π interactions at the N-terminal segment prompts substrate release. Significantly, substrate release is followed by the closure of the intracellular gate and a global reconfiguration back to outward-facing state to resume the transport cycle. Two minimally hydrated intermediates, not structurally resolved to date, are identified: one, substrate-bound, stabilized during the passage from outward- to inward-facing state (holo-occluded), and another, substrate-free, along the reverse transition (apo-occluded).
    Keywords Biology (General) ; QH301-705.5
    Subject code 500
    Language English
    Publishing date 2014-10-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Structural basis of G protein-Coupled receptor CMKLR1 activation and signaling induced by a chemerin-derived agonist.

    Xuan Zhang / Tina Weiß / Mary Hongying Cheng / Siqi Chen / Carla Katharina Ambrosius / Anne Sophie Czerniak / Kunpeng Li / Mingye Feng / Ivet Bahar / Annette G Beck-Sickinger / Cheng Zhang

    PLoS Biology, Vol 21, Iss 12, p e

    2023  Volume 3002188

    Abstract: Chemokine-like receptor 1 (CMKLR1), also known as chemerin receptor 23 (ChemR23) or chemerin receptor 1, is a chemoattractant G protein-coupled receptor (GPCR) that responds to the adipokine chemerin and is highly expressed in innate immune cells, ... ...

    Abstract Chemokine-like receptor 1 (CMKLR1), also known as chemerin receptor 23 (ChemR23) or chemerin receptor 1, is a chemoattractant G protein-coupled receptor (GPCR) that responds to the adipokine chemerin and is highly expressed in innate immune cells, including macrophages and neutrophils. The signaling pathways of CMKLR1 can lead to both pro- and anti-inflammatory effects depending on the ligands and physiological contexts. To understand the molecular mechanisms of CMKLR1 signaling, we determined a high-resolution cryo-electron microscopy (cryo-EM) structure of the CMKLR1-Gi signaling complex with chemerin9, a nanopeptide agonist derived from chemerin, which induced complex phenotypic changes of macrophages in our assays. The cryo-EM structure, together with molecular dynamics simulations and mutagenesis studies, revealed the molecular basis of CMKLR1 signaling by elucidating the interactions at the ligand-binding pocket and the agonist-induced conformational changes. Our results are expected to facilitate the development of small molecule CMKLR1 agonists that mimic the action of chemerin9 to promote the resolution of inflammation.
    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2023-12-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Structural basis of G protein–Coupled receptor CMKLR1 activation and signaling induced by a chemerin-derived agonist

    Xuan Zhang / Tina Weiß / Mary Hongying Cheng / Siqi Chen / Carla Katharina Ambrosius / Anne Sophie Czerniak / Kunpeng Li / Mingye Feng / Ivet Bahar / Annette G. Beck-Sickinger / Cheng Zhang

    PLoS Biology, Vol 21, Iss

    2023  Volume 12

    Keywords Biology (General) ; QH301-705.5
    Language English
    Publishing date 2023-12-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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