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Complex assembly

Ayemeh Bagheri Hashkavayi, Jahan Bakhsh Raoof
In this paper, we report the application of a reusable electrochemical aptasensor for detection of tryptophan by using [Fe(bpy)3 ](p-CH3 C6 H4 SO2 )2 as an electroactive indicator and based on the target-compelled aptamer displacement. The aptasensor fabricated by self-assembling the thiolated probe on the surface of graphite screen-printed electrode modified with gold nanoparticles/multiwalled carbon nanotubes and chitosan nanocomposite (AuNPs/MWCNTs-Chit/SPE). Afterward, Trp aptamer (Apt) immobilized on the modified electrode surface through hybridization...
October 3, 2018: Journal of Pharmaceutical and Biomedical Analysis
Yu-Han Liu, Shu-Chen Kuo, Bing-Yu Yao, Zih-Syun Fang, Yi-Tzu Lee, Yuan-Chih Chang, Te-Li Chen, Che-Ming Jack Hu
Amidst the ever-rising threat of antibiotics resistance, colistin, a decade-old antibiotic with lingering toxicity concern, is increasingly prescribed to treat many drug-resistant, gram-negative bacteria. With the aim of improving the safety profile while preserving the antimicrobial activity of colistin, a nanoformulation is herein developed through coacervate complexation with polyanionic peptides. Upon controlled mixing of cationic colistin with polyglutamic acids, formation of liquid coacervates was demonstrated...
October 10, 2018: Acta Biomaterialia
Qiang Li, Qiangfeng Wang, Xin Jin, Zuqin Chen, Chuan Xiong, Ping Li, Jian Zhao, Wenli Huang
Lyophyllum decastes and Lyophyllum shimeji are the two primary species within the L. decastes complex, and they differ considerably in their nutritional lifestyles and preferred growth environments. However, differences in their mitogenomes have not yet been investigated. In this study, the mitogenomes of the two species were sequenced by next-generation sequencing technology, successfully assembled, and compared. The two mitogenomes of L. decastes and L. shimeji comprised circular DNA molecules of sizes 50,643 bp and 73,678 bp, respectively...
October 10, 2018: International Journal of Biological Macromolecules
Benoit J Kunath, Francesco Delogu, Adrian E Naas, Magnus Ø Arntzen, Vincent G H Eijsink, Bernard Henrissat, Torgeir R Hvidsten, Phillip B Pope
Microbial communities that degrade lignocellulosic biomass are typified by high levels of species- and strain-level complexity, as well as synergistic interactions between both cellulolytic and non-cellulolytic microorganisms. Coprothermobacter proteolyticus frequently dominates thermophilic, lignocellulose-degrading communities with wide geographical distribution, which is in contrast to reports that it ferments proteinaceous substrates and is incapable of polysaccharide hydrolysis. Here we deconvolute a highly efficient cellulose-degrading consortium (SEM1b) that is co-dominated by Clostridium (Ruminiclostridium) thermocellum and multiple heterogenic strains affiliated to C...
October 12, 2018: ISME Journal
Xiechao Zhan, Chuangye Yan, Xiaofeng Zhang, Jianlin Lei, Yigong Shi
The pre-catalytic spliceosome (B complex) is preceded by its precursor spliceosome (pre-B complex) and followed by the activated spliceosome (Bact complex). The pre-B-to-B and B-to-Bact transitions are driven by the ATPase/helicases Prp28 and Brr2, respectively. In this study, we report the cryo-electron microscopy structures of the human pre-B complex and the human B complex at an average resolution of 5.7 and 3.8 Å, respectively. In the pre-B complex, U1 and U2 small nuclear ribonucleoproteins (snRNPs) associate with two edges of the tetrahedron-shaped U4/U6...
October 12, 2018: Cell Research
Sara Roos, Kalliopi Sofou, Carola Hedberg-Oldfors, Gittan Kollberg, Ulrika Lindgren, Christer Thomsen, Mar Tulinius, Anders Oldfors
Mitochondrial myopathies are a heterogeneous group of disorders associated with a wide range of clinical phenotypes. We present a 16-year-old girl with a history of exercise intolerance since childhood. Acylcarnitine species suggestive of multiple acyl-CoA dehydrogenase deficiency were found in serum, however genetic analysis did not reveal variants in genes associated with this disorder. Biochemical analyses of skeletal muscle mitochondria revealed an isolated and extremely low activity of cytochrome c oxidase (COX)...
October 12, 2018: European Journal of Human Genetics: EJHG
Jesper Svedberg, Sara Hosseini, Jun Chen, Aaron A Vogan, Iva Mozgova, Lars Hennig, Pennapa Manitchotpisit, Anna Abusharekh, Thomas M Hammond, Martin Lascoux, Hanna Johannesson
Meiotic drive is widespread in nature. The conflict it generates is expected to be an important motor for evolutionary change and innovation. In this study, we investigated the genomic consequences of two large multi-gene meiotic drive elements, Sk-2 and Sk-3, found in the filamentous ascomycete Neurospora intermedia. Using long-read sequencing, we generated the first complete and well-annotated genome assemblies of large, highly diverged, non-recombining regions associated with meiotic drive elements. Phylogenetic analysis shows that, even though Sk-2 and Sk-3 are located in the same chromosomal region, they do not form sister clades, suggesting independent origins or at least a long evolutionary separation...
October 12, 2018: Nature Communications
Panagiotis L Kastritis, Anne-Claude Gavin
An unprecedented opportunity to integrate ~100 years of meticulous in vitro biomolecular research is currently provided in the light of recent advances in methods to visualize closer-to-native architectures of biomolecular machines, and metabolic enzymes in particular. Traditional views of enzymes, namely biomolecular machines, only partially explain their role, organization and kinetics in the cellular milieu. Enzymes self- or hetero-associate, form fibers, may bind to membranes or cytoskeletal elements, have regulatory roles, associate into higher order assemblies (metabolons) or even actively participate in phase-separated membraneless organelles, and all the above in a transient, temporal and spatial manner in response to environmental changes or structural/functional changes of their assemblies...
October 12, 2018: Essays in Biochemistry
Corinne A Tovey, Paul T Conduit
In this short review, we give an overview of microtubule nucleation within cells. It is nearly 30 years since the discovery of γ-tubulin, a member of the tubulin superfamily essential for proper microtubule nucleation in all eukaryotes. γ-tubulin associates with other proteins to form multiprotein γ-tubulin ring complexes (γ-TuRCs) that template and catalyse the otherwise kinetically unfavourable assembly of microtubule filaments. These filaments can be dynamic or stable and they perform diverse functions, such as chromosome separation during mitosis and intracellular transport in neurons...
October 12, 2018: Essays in Biochemistry
Jeffrey R Dwulit-Smith, Joshua J Hamilton, David M Stevenson, Shaomei He, Ben O Oyserman, Francisco Moya-Flores, Sarahi L Garcia, Daniel Amador-Noguez, Katherine D McMahon, Katrina T Forest
Freshwater lakes harbor complex microbial communities, but these ecosystems are often dominated by acI Actinobacteria. Members of this cosmopolitan lineage are proposed to bolster heterotrophic growth using phototrophy because their genomes encode actino-opsins ( actR) This model has been difficult to validate experimentally because acI are not consistently culturable. Based primarily on genomes from single cells and metagenomes, we provide a detailed biosynthetic route for members of acI clades A and B to synthesize retinal and its carotenoid precursors...
October 12, 2018: Applied and Environmental Microbiology
Emely Thompson, Jodene Eldstrom, Maartje Westhoff, Donald McAfee, David Fedida
The delayed potassium rectifier current, IKs, is assembled from tetramers of KCNQ1 and varying numbers of KCNE1 accessory subunits in addition to calmodulin. This channel complex is important in the response of the cardiac action potential to sympathetic stimulation, during which IKs is enhanced. This is likely due to channels opening more quickly, more often, and to greater sublevel amplitudes during adrenergic stimulation. KCNQ1 alone is unresponsive to cyclic adenosine monophosphate (cAMP), and thus KCNE1 is required for a functional effect of protein kinase A phosphorylation...
September 27, 2018: Biophysical Journal
Caroline Amalie Brunbjerg Hey, Katarina Beata Saltõkowa, Lasse Jonsgaard Larsen, Zeynep Tümer, Karen Brøndum-Nielsen, Karen Grønskov, Tina Duelund Hjortshøj, Lisbeth Birk Møller
Bardet-Biedl syndrome (BBS) is genetically heterogeneous with at least 21 genes involved, and BBS10 encodes, together with BBS6 and BBS12, chaperonin-like proteins which are important for the assembly of the multiprotein complex, the BBSome encoded by other BBS genes. Here we describe the successful generation of an induced pluripotent stem cell (iPSC) line KCi002-A from a male with BBS, homozygous for the disease causing variant c.271insT, p.(Cys91fsX95) in BBS10. Resource table.
September 20, 2018: Stem Cell Research
Kein Takeda, Yoshikazu Tanaka, Naoki Abe, Jun Kaneko
The β-strand stem release system of staphylococcal β-barrel pore-forming toxin γ-hemolysin was investigated. Mutations at K15 and R16 in the cap domain of Hlg2 decreased hemolytic activity more markedly than their effect on erythrocyte binding. In addition, D122N mutation of LukF prestem lost the activity with Hlg2 R16A, indicating that electrostatic interactions between residues in the Hlg2 cap and prestem of adjacent LukF in the ring-shaped complex might serve as a switch for stem release.
October 9, 2018: Toxicon: Official Journal of the International Society on Toxinology
Haniyeh Koochak, Sujith Puthiyaveetil, Daniel L Mullendore, Meng Li, Helmut Kirchhoff
In plants the stacking of part of the photosynthetic thylakoid membrane generates two main sub-compartments: the stacked grana core and unstacked stroma lamellae. However, a third distinct domain, the grana margin, has been postulated but its structural and functional identity remains elusive. Here, an optimized thylakoid fragmentation procedure combined with detailed ultrastructural, biochemical, and functional analyses reveals the distinct composition of grana margins. It is enriched with lipids, cytochrome b6 f complex, and ATPase while depleted in photosystems and light harvesting complexes...
October 12, 2018: Plant Journal: for Cell and Molecular Biology
Shiteshu Shrimal, Reid Gilmore
Asparagine-linked (N-linked) glycosylation is one of the most common protein modification reactions in eukaryotic cells, occurring upon the majority of proteins that enter the secretory pathway. X-ray crystal structures of the single subunit OSTs from eubacterial and archaebacterial organisms revealed the location of donor and acceptor substrate binding sites and provided the basis for a catalytic mechanism. Cryoelectron microscopy structures of the octameric yeast OST provided substantial insight into the organization and assembly of the multisubunit oligosaccharyltransferases...
October 11, 2018: Glycobiology
Justin E Pye, Clay E Wood, Justin C Burton
Experiments and simulations suggest that simple liquids may experience slip while flowing near a smooth, hydrophobic surface. Here we show how precursors to molecular slip can be observed in the complex response of a liquid to oscillatory shear. We measure both the change in frequency and bandwidth of a quartz crystal microbalance during the growth of a single drop of water immersed in an ambient liquid. By varying the hydrophobicity of the surface using self-assembled monolayers, our results show little or no slip for water on all surfaces...
September 28, 2018: Physical Review Letters
X Edward Zhou, Karsten Melcher, H Eric Xu
G protein-coupled receptors (GPCRs) constitute the largest family of cell surface receptors that mediate numerous cell signaling pathways, and are targets of more than one-third of clinical drugs. Thanks to the advancement of novel structural biology technologies, high-resolution structures of GPCRs in complex with their signaling transducers, including G-protein and arrestin, have been determined. These 3D complex structures have significantly improved our understanding of the molecular mechanism of GPCR signaling and provided a structural basis for signaling-biased drug discovery targeting GPCRs...
October 12, 2018: Protein Science: a Publication of the Protein Society
Bijayananda Panigrahi, Rohit Kumar Singh, Sourav Mishra, Dindyal Mandal
RNA interference shows a great strategy for biological studies; however, delivering of small interfering RNA (siRNA) remains challenging. Although several delivery vehicles, including cell-penetrating peptides, have been developed, their implementation is often restricted because of their endosomal entrapment. Herein, we report the formation of self-assembled nanostructures from rationally designed cyclic peptides and explore them for efficient delivery of functional biomacromolecules such as siRNA into mammalian cells...
October 12, 2018: Artificial Cells, Nanomedicine, and Biotechnology
Yang Bai, Cai Ping Liu, Xin Song, Longhai Zhuo, Huaitian Bu, Wei Tian
Despite the progress has been made in the application of supramolecular prodrug self-assemblies to enhance the functionality of drug delivery systems, the corresponding research on multiple responsive supramolecular prodrug self-assemblies for programmed drug delivery is still limited. In this paper, the synthesis and self-assembly behaviours of supramolecular prodrug complexes (SPCs) with β-cyclodextrin-acylhydrazone-DOX and the targeting of azobenzene-terminated poly(2-(dimethylamino)ethyl methacrylate) (Azo-PDMA-FA) as building blocks are investigated and described...
October 11, 2018: Chemistry, An Asian Journal
Alexis Zukowski, Juliana Phillips, Soyeon Park, Ronghu Wu, Steven P Gygi, Aaron M Johnson
Heterochromatin domains are stably repressed chromatin structures composed of a core assembly of silencing proteins that condense adjacent nucleosomes. The minimal heterochromatin structure can serve as a platform for recruitment of complementary regulatory factors. We find that a reconstituted budding yeast heterochromatin domain can act as a platform to recruit multiple factors that play a role in regulating heterochromatin function. We uncover the direct interaction between the SIR heterochromatin complex and a chromosomal boundary protein that restricts the spread of heterochromatin...
October 12, 2018: Current Genetics
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