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https://www.readbyqxmd.com/read/27921994/the-structure-of-sv40-large-t-hexameric-helicase-in-complex-with-at-rich-origin-dna
#1
Dahai Gai, Damian Wang, Shu-Xing Li, Xiaojiang S Chen
DNA replication is a fundamental biological process. The initial step in eukaryotic DNA replication is the assembly of the pre-initiation complex, including the formation of two head-to-head hexameric helicases around the replication origin. How these hexameric helicases interact with their origin dsDNA remains unknown. Here, we report the co-crystal structure of the SV40 Large-T Antigen (LT) hexameric helicase bound to its origin dsDNA. The structure shows that the six subunits form a near-planar ring that interacts with the origin, so that each subunit makes unique contacts with the DNA...
December 6, 2016: ELife
https://www.readbyqxmd.com/read/27921280/ph-responsive-triblock-copolymeric-micelles-decorated-with-a-cell-penetrating-peptide-provide-efficient-doxorubicin-delivery
#2
Khen Eng Ng, Mohd Cairul Iqbal Mohd Amin, Haliza Katas, Muhammad Wahab Amjad, Adeel Masood Butt, Prashant Kesharwani, Arun K Iyer
This study developed novel triblock pH-responsive polymeric micelles (PMs) using cholic acid-polyethyleneimine-poly-L-arginine (CA-PEI-pArg) copolymers. PEI provided pH sensitivity, while the hydrophilic cell-penetrating pArg peptide promoted cellular PM internalization. The copolymers self-assembled into PMs in aqueous solution at above the critical micelle concentration (2.98 × 10(-7) M) and encapsulated doxorubicin in the core region, with a 34.2% (w/w) entrapment efficiency. PMs showed pH-dependent swelling, increasing in size by almost sevenfold from pH 7...
December 2016: Nanoscale Research Letters
https://www.readbyqxmd.com/read/27920892/surface-modification-and-cellular-uptake-evaluation-of-au-coated-ni80fe20-nanodiscs-for-biomedical-applications
#3
Gabriele Barrera, Loredana Serpe, Federica Celegato, Marco Coїsson, Katia Martina, Roberto Canaparo, Paola Tiberto
A nanofabrication technique based on self-assembling of polystyrene nanospheres is used to obtain magnetic Ni80Fe20 nanoparticles with a disc shape. The free-standing nanodiscs (NDs) have diameter and thickness of about 630 nm and 30 nm, respectively. The versatility of fabrication technique allows one to cover the ND surface with a protective gold layer with a thickness of about 5 nm. Magnetization reversal has been studied by room-temperature hysteresis loop measurements in water-dispersed free-standing NDs...
December 6, 2016: Interface Focus
https://www.readbyqxmd.com/read/27920533/effect-of-inserted-spacer-in-hepatic-cell-penetrating-multifunctional-peptide-component-on-the-dna-intracellular-delivery-of-quaternary-complexes-based-on-modular-design
#4
Luchen Zhang, Zhenbo Li, Fangli Sun, Yuhong Xu, Zixiu Du
A safe and efficient quaternary gene delivery system (named Q-complexes) was constructed based on self-assembly of molecules through noncovalent bonds. This system was formulated through the cooperation and competing interactions of cationic liposomes, multifunctional peptides, and DNA, followed by coating hyaluronic acid on the surface of the ternary complexes. The multifunctional peptide was composed of two functional domains: penetrating hepatic tumor-targeted cell moiety (KRPTMRFRYTWNPMK) and a wrapping gene sequence (polyarginine 16)...
2016: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/27920255/mlkl-channel-in-necroptosis-is-octamer-formed-by-tetramers-in-a-dyadic-process
#5
Deli Huang, Xinru Zheng, Zi-An Wang, Xin Chen, Wan-Ting He, Yingying Zhang, Jin-Gen Xu, Hang Zhao, Wenke Shi, Xin Wang, Yongqun Zhu, Jiahuai Han
Oligomerization of the mixed lineage kinase domain-like protein (MLKL) is essential for its cation channel function in necroptosis. Here we show that the MLKL channel is an octamer comprising of two previously identified tetramers most likely in their side-by-side position. Inter-molecule disulfide bonds are present in the tetramer but are not required for the octamer assembly and necroptosis. MLKL forms oligomers in the necrosome, and is then released from the necrosome before or during its membrane translocation...
December 5, 2016: Molecular and Cellular Biology
https://www.readbyqxmd.com/read/27920254/casein-kinase-2-is-linked-to-stress-granule-dynamics-through-phosphorylation-of-the-stress-granule-nucleating-protein-g3bp1
#6
Lucas C Reineke, Wei-Chih Tsai, Antrix Jain, Jason T Kaelber, Sung Yun Jung, Richard E Lloyd
Stress granules are large macromolecular aggregates that contain translation initiation complexes and mRNAs. Stress granule formation coincides with translational repression, and stress granules actively signal to mediate cell fate decisions by a) signaling to the translation apparatus to maintain translational repression, b) mount various transcriptional responses including innate immunity, and c) to repress apoptosis. Previous work showed G3BP1 is phosphorylated at serine 149, which regulates G3BP1 oligomerization, stress granule assembly, and RNase activity intrinsic to G3BP1...
December 5, 2016: Molecular and Cellular Biology
https://www.readbyqxmd.com/read/27920201/the-streptococcus-gordonii-adhesin-csha-binds-host-fibronectin-via-a-catch-clamp-mechanism
#7
Catherine R Back, Maryta N Sztukowska, Marisa Till, Richard J Lamont, Howard F Jenkinson, Angela H Nobbs, Paul R Race
Adherence of bacteria to biotic or abiotic surfaces is a prerequisite for host colonization and represents an important step in microbial pathogenicity. This attachment is facilitated by bacterial adhesins at the cell surface. Due to their size and often elaborate multi-domain architectures, these polypeptides represent challenging targets for detailed structural and functional characterization. The multifunctional fibrillar adhesin CshA, which mediates binding to both host molecules and other microorganisms, is an important determinant of colonisation by Streptococcus gordonii, an oral commensal and opportunistic pathogen of animals and humans...
December 5, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27920034/domestication-of-a-housekeeping-transglycosylase-for-assembly-of-a-type-vi-secretion-system
#8
Yoann G Santin, Eric Cascales
The type VI secretion system (T6SS) is an anti-bacterial weapon comprising a contractile tail anchored to the cell envelope by a membrane complex. The TssJ, TssL, and TssM proteins assemble a 1.7-MDa channel complex that spans the cell envelope, including the peptidoglycan layer. The electron microscopy structure of the TssJLM complex revealed that it has a diameter of ~18 nm in the periplasm, which is larger than the size of peptidoglycan pores (~2 nm), hence questioning how the T6SS membrane complex crosses the peptidoglycan layer...
December 5, 2016: EMBO Reports
https://www.readbyqxmd.com/read/27919801/folic-acid-capped-pegylated-magnetic-nanoparticles-enter-cancer-cells-mostly-via-clathrin-dependent-endocytosis
#9
Emilie Allard-Vannier, Katel Hervé-Aubert, Karine Kaaki, Thibaut Blondy, Anastasia Shebanova, Konstantin V Shaitan, Anastasia A Ignatova, Marie-Louise Saboungi, Alexey V Feofanov, Igor Chourpa
BACKGROUND: This work is focused on mechanisms of uptake in cancer cells of rationally designed, covalently assembled nanoparticles, made of superparamagnetic iron oxide nanoparticles (SPIONs), fluorophores (doxorubicin or Nile Blue), polyethylene glycol (PEG) and folic acid (FA), referred hereinafter as SFP-FA. METHODS: SFP-FA were characterized by DLS, zetametry and fluorescence spectroscopy. The SFP-FA uptake in cancer cells was monitored using fluorescence-based methods like fluorescence-assisted cell sorting, LSCM with single-photon and two-photon excitation...
December 2, 2016: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/27919756/molecular-identification-and-functional-delineation-of-a-glutathione-reductase-homologue-from-disk-abalone-haliotis-discus-discus-insights-as-a-potent-player-in-host-antioxidant-defense
#10
H M L P B Herath, P D S U Wickramasinghe, S D N K Bathige, R G P T Jayasooriya, Gi-Young Kim, Myoung Ae Park, Chul Kim, Jehee Lee
Glutathione reductase (GSR) is an enzyme that catalyzes the biochemical conversion of oxidized glutathione (GSSG) into the reduced form (GSH). Since the ratio between the two forms of glutathione (GSH/GSSG) is important for the optimal function of GSH to act as an antioxidant against H2O2, the contribution of GSR as an enzymatic regulatory agent to maintain the proper ratio is essential. Abalones are marine mollusks that frequently encounter environmental factors that can trigger the overproduction of reactive oxygen species (ROS) such as H2O2...
December 2, 2016: Fish & Shellfish Immunology
https://www.readbyqxmd.com/read/27919320/calcium-mediated-actin-reset-caar-mediates-acute-cell-adaptations
#11
Pauline Wales, Christian E Schuberth, Roland Aufschnaiter, Johannes Fels, Ireth García-Aguilar, Annette Janning, Christopher P Dlugos, Marco Schäfer-Herte, Christoph Klingner, Mike Wälte, Julian Kuhlmann, Ekaterina Menis, Laura Hockaday Kang, Kerstin C Maier, Wenya Hou, Antonella Russo, Henry N Higgs, Hermann Pavenstädt, Thomas Vogl, Johannes Roth, Britta Qualmann, Michael M Kessels, Dietmar E Martin, Bela Mulder, Roland Wedlich-Söldner
Actin has well established functions in cellular morphogenesis. However, it is not well understood how the various actin assemblies in a cell are kept in a dynamic equilibrium, in particular when cells have to respond to acute signals. Here, we characterize a rapid and transient actin reset in response to increased intracellular calcium levels. Within seconds of calcium influx, the formin INF2 stimulates filament polymerization at the endoplasmic reticulum (ER), while cortical actin is disassembled. The reaction is then reversed within a few minutes...
December 6, 2016: ELife
https://www.readbyqxmd.com/read/27919266/arrest-at-the-diplotene-stage-of-meiotic-prophase-i-is-delayed-by-progesterone-but-is-not-required-for-primordial-follicle-formation-in-mice
#12
Sudipta Dutta, Deion M Burks, Melissa E Pepling
BACKGROUND: In mammalian females, reproductive capacity is determined by the size of the primordial follicle pool. During embryogenesis, oogonia divide mitotically but cytokinesis is incomplete so oogonia remain connected in germ cell cysts. Oogonia begin to enter meiosis at 13.5 days postcoitum in the mouse and over several days, oocytes progress through the stages of meiotic prophase I arresting in the diplotene stage. Concurrently, germ cell cysts break apart and individual oocytes become surrounded by granulosa cells forming primordial follicles...
December 5, 2016: Reproductive Biology and Endocrinology: RB&E
https://www.readbyqxmd.com/read/27919079/receptor-usage-dictates-hiv-1-restriction-by-human-trim5%C3%AE-in-dendritic-cell-subsets
#13
Carla M S Ribeiro, Ramin Sarrami-Forooshani, Laurentia C Setiawan, Esther M Zijlstra-Willems, John L van Hamme, Wikky Tigchelaar, Nicole N van der Wel, Neeltje A Kootstra, Sonja I Gringhuis, Teunis B H Geijtenbeek
The most prevalent route of HIV-1 infection is across mucosal tissues after sexual contact. Langerhans cells (LCs) belong to the subset of dendritic cells (DCs) that line the mucosal epithelia of vagina and foreskin and have the ability to sense and induce immunity to invading pathogens. Anatomical and functional characteristics make LCs one of the primary targets of HIV-1 infection. Notably, LCs form a protective barrier against HIV-1 infection and transmission. LCs restrict HIV-1 infection through the capture of HIV-1 by the C-type lectin receptor Langerin and subsequent internalization into Birbeck granules...
December 7, 2016: Nature
https://www.readbyqxmd.com/read/27919066/designed-proteins-induce-the-formation-of-nanocage-containing-extracellular-vesicles
#14
Jörg Votteler, Cassandra Ogohara, Sue Yi, Yang Hsia, Una Nattermann, David M Belnap, Neil P King, Wesley I Sundquist
Complex biological processes are often performed by self-organizing nanostructures comprising multiple classes of macromolecules, such as ribosomes (proteins and RNA) or enveloped viruses (proteins, nucleic acids and lipids). Approaches have been developed for designing self-assembling structures consisting of either nucleic acids or proteins, but strategies for engineering hybrid biological materials are only beginning to emerge. Here we describe the design of self-assembling protein nanocages that direct their own release from human cells inside small vesicles in a manner that resembles some viruses...
November 30, 2016: Nature
https://www.readbyqxmd.com/read/27918445/docetaxel-loaded-self-assembly-stearic-acid-modified-bletilla-striata-polysaccharide-micelles-and-their-anticancer-effect-preparation-characterization-cellular-uptake-and-in-vitro-evaluation
#15
Qingxiang Guan, Dandan Sun, Guangyuan Zhang, Cheng Sun, Miao Wang, Danyang Ji, Wei Yang
Poorly soluble drugs have low bioavailability after oral administration, thereby hindering effective drug delivery. A novel drug-delivery system of docetaxel (DTX)-based stearic acid (SA)-modified Bletilla striata polysaccharides (BSPs) copolymers was successfully developed. Particle size, zeta potential, encapsulation efficiency (EE), and loading capacity (LC) were determined. The DTX release percentage in vitro was determined using high performance liquid chromatography (HPLC). The hemolysis and in vitro anticancer activity were studied...
December 2, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/27918050/self-assembled-pt2l2-boxes-strongly-bind-g-quadruplex-dna-and-influence-gene-expression-in-cancer-cells
#16
O Domarco, D Lötsch, J Schreiber, C Dinhof, S Van Schoonhoven, M D García, C Peinador, B K Keppler, W Berger, A Terenzi
Supramolecular Pt(ii) quadrangular boxes bind native and G-quadruplex DNA motifs in a size-dependent fashion. Three Pt molecular squares of distinct size show biological activity against cancer cells and heavily influence the expression of genes known to form G-quadruplexes in their promoter regions. The smallest Pt-box displays less activity but more selectivity for a quadruplex formed in the c-Kit gene.
December 5, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27918015/highly-efficient-polymer-solar-cells-by-step-by-step-optimizing-donor-molecular-packing-and-acceptor-redistribution
#17
Qianqian Sun, Fujun Zhang, Qiaoshi An, Miao Zhang, Jian Wang, Jian Zhang
The dynamic drying process of the active layer should play a vitally important role in determining the performance of polymer solar cells (PSCs). Donor molecular packing and acceptor redistribution can be optimized by two successive post-treatments on the active layer. The blend films were freshly prepared by spin-coating method and then immediately transferred to a covered glass Petri dish to allow self-assembly of the donor molecules. The films were then treated with methanol or PFN-methanol solution to adjust the acceptor redistribution...
December 5, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27917907/ecat1-is-essential-for-human-oocyte-maturation-and-pre-implantation-development-of-the-resulting-embryos
#18
Changyu Liu, Min Li, Tianjie Li, Hongcui Zhao, Jin Huang, Yun Wang, Qian Gao, Yang Yu, Qinghua Shi
ECAT1 is a subunit of the subcortical maternal complex that is required for cell cycle progression during pre-implantation embryonic development; however, its exact function remains to be elucidated. Here we investigated the expression of ECAT1 in human ovarian tissue, oocytes and pre-implantation embryos and assessed its function by using RNA interference (RNAi) in oocytes. ECAT1 mRNA was highly expressed in human oocytes and zygotes, as well as in two-cell, four-cell and eight-cell embryos, but declined significantly in morulae and blastocysts...
December 5, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27917837/purification-crystallization-and-characterization-of-the-pseudomonas-outer-membrane-protein-fapf-a-functional-amyloid-transporter
#19
Sarah L Rouse, Wlliam J Hawthorne, Sebastian Lambert, Marc L Morgan, Stephen A Hare, Stephen Matthews
Bacteria often produce extracellular amyloid fibres via a multi-component secretion system. Aggregation-prone, unstructured subunits cross the periplasm and are secreted through the outer membrane, after which they self-assemble. Here, significant progress is presented towards solving the high-resolution crystal structure of the novel amyloid transporter FapF from Pseudomonas, which facilitates the secretion of the amyloid-forming polypeptide FapC across the bacterial outer membrane. This represents the first step towards obtaining structural insight into the products of the Pseudomonas fap operon...
December 1, 2016: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/27917835/coxsackievirus-b3-protease-3c-expression-purification-crystallization-and-preliminary-structural-insights
#20
Stavroula Fili, Alexandros Valmas, Magdalini Christopoulou, Maria Spiliopoulou, Nikos Nikolopoulos, Julie Lichière, Souzana Logotheti, Fotini Karavassili, Eleftheria Rosmaraki, Andrew Fitch, Jonathan Wright, Detlef Beckers, Thomas Degen, Gwilherm Nénert, Rolf Hilgenfeld, Nicolas Papageorgiou, Bruno Canard, Bruno Coutard, Irene Margiolaki
Viral proteases are proteolytic enzymes that orchestrate the assembly of viral components during the viral life cycle and proliferation. Here, the expression, purification, crystallization and preliminary X-ray diffraction analysis are presented of protease 3C, the main protease of an emerging enterovirus, coxsackievirus B3, that is responsible for many cases of viral myocarditis. Polycrystalline protein precipitates suitable for X-ray powder diffraction (XRPD) measurements were produced in the presence of 22-28%(w/v) PEG 4000, 0...
December 1, 2016: Acta Crystallographica. Section F, Structural Biology Communications
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