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Protein membrane interactions

Zuriñe Antón, Ane Landajuela, Javier H Hervás, L Ruth Montes, Sonia Hernández-Tiedra, Guillermo Velasco, Felix M Goñi, Alicia Alonso
The phospholipid cardiolipin (CL) has been proposed to play a role in selective mitochondrial autophagy, or mitophagy. CL externalization to the outer mitochondrial membrane would act as a signal for the human Atg8 ortholog subfamily, MAP1LC3 (LC3). The latter would mediate both mitochondrial recognition and autophagosome formation, ultimately leading to removal of damaged mitochondria. We have applied quantitative biophysical techniques to the study of CL interaction with various Atg8 human orthologs, namely LC3B, GABARAPL2 and GABARAP...
October 20, 2016: Autophagy
Binod Kumar, Dipanjan Dutta, Jawed Iqbal, Mairaj Ahmed Ansari, Arunava Roy, Leela Chikoti, Gina Pisano, Mohanan Valiya Veettil, Bala Chandran
Kaposi's sarcoma-associated herpesvirus (KSHV) binding to the endothelial cell surface heparan sulfate is followed by sequential interactions with α3β1, αVβ3 and αVβ5 integrins and Ephrin A2 receptor tyrosine kinase (EphA2R). These interactions activate host cell pre-existing FAK, Src, PI3-K and RhoGTPase signaling cascades, c-Cbl mediated ubiquitination of receptors, recruitment of CIB1, p130Cas and Crk adaptor molecules, and membrane bleb formation leading to lipid raft dependent macropinocytosis of KSHV into human microvascular dermal endothelial (HMVEC-d) cells...
October 2016: PLoS Pathogens
Juexin Wang, Dingding Shen, Geqing Xia, Wangzhen Shen, Robert L Macdonald, Dong Xu, Jing-Qiong Kang
Mutations in GABAA receptor subunit genes are frequently associated with epilepsy, and nonsense mutations in GABRG2 are associated with several epilepsy syndromes including childhood absence epilepsy, generalized tonic clonic seizures and the epileptic encephalopathy, Dravet syndrome. The molecular basis for the phenotypic heterogeneity of mutations is unclear. Here we focused on three nonsense mutations in GABRG2 (GABRG2(R136*), GABRG2(Q390*) and GABRG2(W429*)) associated with epilepsies of different severities...
October 20, 2016: Scientific Reports
Jingjing Li, Jin Gao, Lei Han, Yinjie Zhang, Wen Guan, Liang Zhou, Yan Yu, Wei Han
Identifying interactions between ligands and transmembrane receptors is crucial for understanding the endocrine system. However, the present approaches for this purpose are still not capable of high-throughput screening. In this report, a membrane-anchored ligand and receptor yeast two-hybrid (MALAR-Y2H) system was established. In the method, an extracellular ligand is linked with an intracellular split-ubiquitin reporter system via a chimeric transmembrane structure. Meanwhile, the prey proteins of transmembrane receptors are fused to the other half of the split-ubiquitin reporter system...
October 20, 2016: Scientific Reports
Stacy L DeBlasio, Richard S Johnson, Michael J MacCoss, Stewart M Gray, Michelle Cilia
Phloem localization of plant viruses is advantageous for acquisition by sap-sucking vectors but hampers host-virus protein interaction studies. In this study, Potato leafroll virus (PLRV)-host protein complexes were isolated from systemically infected potato, a natural host of the virus. Comparing two different co-immunoprecipitation support matrices coupled to mass spectrometry, we identified 44 potato proteins and one viral protein (P1) specifically associated with virus isolated from infected phloem. An additional 142 proteins interact in complex with virus at varying degrees of confidence...
October 20, 2016: Journal of Proteome Research
Xiaohui Liu, Ting Dong, Yu Zhou, Niu Huang, Xiaoguang Lei
Glycolipids are important structural components of biological membranes and perform crucial functions in living systems, including signaling transduction and interaction with extracellular environment. However, the mechanistic exploration of glycolipids in vivo is challenging because they are not genetically encoded. Herein, we designed and synthesized a series of bifunctional monogalactosyldiacylglycerol (MGDG) probes as a model by introducing diazirine and terminal alkyne moieties on an aliphatic chain. In combination with proteome profiling and molecular modeling, we have demonstrated that MGDG alleviates inflammation by antagonizing TLR4...
October 20, 2016: Angewandte Chemie
Yvonne Schaletzki, Marie-Luise Kromrey, Susanne Bröderdorf, Elke Hammer, Markus Grube, Paul Hagen, Sonja Sucic, Michael Freissmuth, Uwe Völker, Andreas Greinacher, Bernhard H Rauch, Heyo K Kroemer, Gabriele Jedlitschky
The multidrug resistance protein 4 (MRP4/ABCC4) has been identified as an important transporter for signalling molecules including cyclic nucleotides and several lipid mediators in platelets and may thus represent a novel target to interfere with platelet function. Besides its localisation in the plasma membrane, MRP4 has been also detected in the membrane of dense granules in resting platelets. In polarised cells it is localised at the basolateral or apical plasma membrane. To date, the mechanism of MRP4 trafficking has not been elucidated; protein interactions may regulate both the localisation and function of this transporter...
October 20, 2016: Thrombosis and Haemostasis
Can-Zhao Liu, Xiang-Yu Li, Ren-Hong Du, Min Gao, Ming-Ming Ma, Fei-Ya Li, Er-Wen Huang, Hong-Shuo Sun, Guan-Lei Wang, Yong-Yuan Guan
BACKGROUND: Previous research has demonstrated that ClC-3 is responsible for volume-regulated Cl(-)current (ICl.vol) in vascular smooth muscle cells (VSMCs). However, it is still not clear whether and how ClC-3 is transported to cell membranes, resulting in alteration ofICl.vol.Methods and Results:Volume-regulated chloride current (ICl.vol) was recorded by whole-cell patch clamp recording, and Western blotting and co-immunoprecipitation were performed to examine protein expression and protein-protein interaction...
October 19, 2016: Circulation Journal: Official Journal of the Japanese Circulation Society
Jamal El-Saghir, Farah Nassar, Nadim Tawil, Marwan El-Sabban
BACKGROUND: Exosomes are membrane nano-vesicles secreted by a multitude of cells that harbor biological constituents such as proteins, lipids, mRNA and microRNA. Exosomes can potentially transfer their cargo to other cells, implicating them in many patho-physiological processes. Mesenchymal stem cells (MSCs), residents of the bone marrow and metastatic niches, potentially interact with cancer cells and/or their derived exosomes. In this study, we investigated whether exosomes derived from adult T-cell leukemia/lymphoma (ATL) cells act as intercellular messengers delivering leukemia-related genes that modulate the properties of human MSCs in favor of leukemia...
October 19, 2016: Retrovirology
Nuria Roldan, Thomas K M Nyholm, J Peter Slotte, Jesús Pérez-Gil, Begoña García-Álvarez
To allow breathing and prevent alveolar collapse, lung surfactant (LS) develops a complex membranous system at the respiratory surface. LS is defined by a specific protein and lipid composition, including saturated and unsaturated phospholipid species and cholesterol. Surfactant protein C (SP-C) has been suggested to be an essential element for sustaining the presence of cholesterol in surfactant without functional impairment. In this work, we used a fluorescent sterol-partitioning assay to assess the effect of the surfactant proteins SP-B and SP-C on cholesterol distribution in membranes...
October 18, 2016: Biophysical Journal
Maite L Ortiz-Suarez, Firdaus Samsudin, Thomas J Piggot, Peter J Bond, Syma Khalid
OmpA is a multidomain protein found in the outer membranes of most Gram-negative bacteria. Despite a wealth of reported structural and biophysical studies, the structure-function relationships of this protein remain unclear. For example, it is still debated whether it functions as a pore, and the precise molecular role it plays in attachment to the peptidoglycan of the periplasm is unknown. The absence of a consensus view is partly due to the lack of a complete structure of the full-length protein. To address this issue, we performed molecular-dynamics simulations of the full-length model of the OmpA dimer proposed by Robinson and co-workers...
October 18, 2016: Biophysical Journal
Krystal A Morales, Yuan Yang, Taylor R Cole, Tatyana I Igumenova
Ca(2+)-dependent conserved-region 2 (C2) domains target their host signaling proteins to anionic membranes. The Ca(2+)-binding event is a prerequisite for membrane association. Here, we investigate multiscale metal-ion-dependent dynamics of the C2 domain of protein kinase Cα (C2α) using NMR spectroscopy. Interactions with metal ions attenuate microsecond-timescale motions of the loop regions, indicating that preorganization of the metal-binding loops occurs before membrane insertion. Binding of a full complement of Ca(2+) ions has a profound effect on the millisecond-timescale dynamics of the N- and C-terminal regions of C2α...
October 18, 2016: Biophysical Journal
Priyanka Dutta, Ahnaf Siddiqui, Mohsen Botlani, Sameer Varma
Nipah is an emerging paramyxovirus that is of serious concern to human health. It invades host cells using two of its membrane proteins-G and F. G binds to host ephrins and this stimulates G to activate F. Upon activation, F mediates virus-host membrane fusion. Here we focus on mechanisms that underlie the stimulation of G by ephrins. Experiments show that G interacts with ephrin and F through separate sites located on two different domains, the receptor binding domain (RBD) and the F activation domain (FAD)...
October 18, 2016: Biophysical Journal
Jessica M Wilson, Jeremy W Prokop, Ellen Lorimer, Elizabeth Ntantie, Carol L Williams
Two isoforms of the small GTPase Rap1, Rap1A and Rap1B, participate in cell adhesion; Rap1A promotes steady state adhesion, while Rap1B regulates dynamic changes in cell adhesion. These events depend on the prenylation of Rap1, which promotes its membrane localization. Here, we identify previously unsuspected differences in the regulation of prenylation of Rap1A versus Rap1B, due in part to their different phosphorylation-dependent interactions with the chaperone protein SmgGDS-607. Previous studies indicate that activation of Gαs protein-coupled receptors (GPCRs) phosphorylates S-179 and S-180 in the polybasic region (PBR) of Rap1B, which inhibits Rap1B binding to SmgGDS-607 and diminishes Rap1B prenylation and membrane localization...
October 16, 2016: Journal of Molecular Biology
Martin Sztacho, Sandra Segeletz, Maria Arantzazu Sanchez-Fernandez, Cornelia Czupalla, Christian Niehage, Bernard Hoflack
Bone resorption in vertebrates relies on the ability of osteoclasts to assemble F-actin-rich podosomes that condense into podosomal belts, forming sealing zones. Sealing zones segregate bone-facing ruffled membranes from other membrane domains, and disassemble when osteoclasts migrate to new areas. How podosome/sealing zone dynamics is regulated remains unknown. We illustrate the essential role of the membrane scaffolding F-BAR-Proline-Serine-Threonine Phosphatase Interacting Proteins (PSTPIP) 1 and 2 in this process...
2016: PloS One
Kai Xu, Peter D Nagy
Positive-strand RNA viruses build extensive membranous replication compartments to support replication and protect the virus from antiviral responses by the host. These viruses require host factors and various lipids to form viral replication complexes (VRCs). The VRCs built by Tomato bushy stunt virus (TBSV) are enriched with phosphatidylethanolamine (PE) through a previously unknown pathway. To unravel the mechanism of PE enrichment within the TBSV replication compartment, in this paper, the authors demonstrate that TBSV co-opts the guanosine triphosphate (GTP)-bound active form of the endosomal Rab5 small GTPase via direct interaction with the viral replication protein...
October 2016: PLoS Biology
Lily Dara, Zhang-Xu Liu, Neil Kaplowitz
Hepatocyte death, which can be apoptosis or necrosis depending on the context, is a prominent feature of liver disease. The lectin concanavalin A (ConA) activates immune cells, resulting in inflammatory liver injury and hepatocyte necrosis. In this issue of the JCI, Günther et al. demonstrate that the pseudokinase mixed lineage kinase domain-like protein (MLKL) participates in hepatocyte death in ConA injury and that MLKL-mediated death is independent of the receptor-interacting protein kinase RIPK3. RIPK3 was absent in hepatocytes, and MLKL-deficient mice, but not RIPK3-deficient mice, were protected from ConA-induced liver injury...
October 17, 2016: Journal of Clinical Investigation
Rebba C Boswell-Casteel, Franklin A Hays
Equilibrative nucleoside transporters (ENTs) are polytopic integral membrane proteins that mediate the transport of nucleosides, nucleobases, and therapeutic analogs. The best-characterized ENTs are the human transporters hENT1 and hENT2. However, non-mammalian eukaryotic ENTs have also been studied (e.g., yeast, parasitic protozoa). ENTs are major pharmaceutical targets responsible for modulating the efficacy of more than 30 approved drugs. However, the molecular mechanisms and chemical determinants of ENT-mediated substrate recognition, binding, inhibition, and transport are poorly understood...
October 19, 2016: Nucleosides, Nucleotides & Nucleic Acids
Tao Yin, Hui Li, Lin Su, Shuo Liu, Chunwei Yuan, Degang Fu
Electron transfer kinetics of Shewanella loihica PV-4 at the up-growing TiO2 nanosheet (TiO2-NS) modified carbon paper (CP) electrode was investigated. The effect of TiO2-NSs, which speeds up the interfacial electron transfer of outer membrane c-type cytochromes (OMCs), was revealed for the first time. TiO2-NSs with a polar surface modified hydrophobic CP into super-hydrophilic TiO2-NS/CP. The favorable interaction between PV-4 and TiO2-NSs not only enhanced microbial adhesion, but also altered the redox nature of OMCs...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Koji Nakamura, Kenjiro Sawada, Yasuto Kinose, Akihiko Yoshimura, Aska Toda, Erika Nakatsuka, Kae Hashimoto, Seiji Mabuchi, Ken-Ichirou Morishige, Hirohisa Kurachi, Ernst Lengyel, Tadashi Kimura
: Epithelial ovarian cancer (EOC) cells metastasize within the peritoneal cavity and directly encounter human peritoneal mesothelial cells (HPMCs) as the initial step of metastasis. The contact between ovarian cancer cells and the single layer of mesothelial cells involves direct communications that modulate cancer progression but the mechanisms are unclear. One candidate mediating cell-cell communications are exosomes, 30-100 nm membrane vesicles of endocytic origin, through the cell-cell transfer of proteins, mRNAs, or microRNAs...
October 6, 2016: Molecular Cancer Research: MCR
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