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Tetramer

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https://www.readbyqxmd.com/read/28808061/structural-analyses-of-the-bacterial-primosomal-protein-dnab-reveal-that-it-is-a-tetramer-and-forms-a-complex-with-a-primosomal-re-initiation-protein
#1
Yi-Ching Li, Vankadari Naveen, Min-Guan Lin, Chwan-Deng Hsiao
The DnaB primosomal protein from Gram-positive bacteria plays a key role in DNA replication and restart as a loader protein for the recruitment of replisome cascade proteins. Previous investigations have established that DnaB is composed of an N-terminal domain, a middle domain, and a C-terminal domain. However, structural evidence for how DnaB functions at the atomic level is lacking. Here, we report the crystal structure of DnaB, encompassing the N-terminal and middle domains (residues 1-300), from Geobacillus stearothermophilus (GstDnaB1-300) at 2...
August 14, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28805461/a-new-caffeic-acid-tetramer-from-the-dracocephalum-moldavica-l
#2
Jun-Liang Zhang, Ren-Jie Yan, Ning Yu, Xue Zhang, Dai-Jie Chen, Tong Wu, Jian-Guo Xin
A new caffeic acid tetramer compound, named (+) methyl rabdosiin (4), together with seven known caffeic acid multimers (1-3, 5-8) and one caffeic acid monomer (9), were isolated from the aerial parts of Dracocephalum moldavica L. The structures of these compounds were assigned on the basis of 1D and 2D NMR spectroscopic and mass spectrometry analyses. The protective effects of compounds 2-4 against hydrogen peroxide (H2O2)-induced apoptosis were evaluated in primary cardiomyocytes of SD neonatal rats in vitro by the MTT method...
August 14, 2017: Natural Product Research
https://www.readbyqxmd.com/read/28803692/a-janus-faced-im30-ring-involved-in-thylakoid-membrane-fusion-is-assembled-from-im30-tetramers
#3
Michael Saur, Raoul Hennig, Phoebe Young, Kristiane Rusitzka, Nadja Hellmann, Jennifer Heidrich, Nina Morgner, Jürgen Markl, Dirk Schneider
Biogenesis and dynamics of thylakoid membranes likely involves membrane fusion events. Membrane attachment of the inner membrane-associated protein of 30 kDa (IM30) affects the structure of the lipid bilayer, finally resulting in membrane fusion. Yet, how IM30 triggers membrane fusion is largely unclear. IM30 monomers pre-assemble into stable tetrameric building blocks, which further align to form oligomeric ring structures, and differently sized IM30 rings bind to membranes. Based on a 3D reconstruction of IM30 rings, we locate the IM30 loop 2 region at the bottom of the ring and show intact membrane binding but missing fusogenic activity of loop 2 mutants...
August 2, 2017: Structure
https://www.readbyqxmd.com/read/28803470/effect-of-dmso-on-protein-structure-and-interactions-assessed-by-collision-induced-dissociation-and-unfolding
#4
Daniel S-H Chan, Madeline E Eve Kavanagh, Kirsty J McLean, Andrew William Munro, Dijana Matak-Vinkovic, Anthony G Coyne, Chris Abell
Native mass spectrometry is an ideal technique to investigate the effects of DMSO on protein structure and interac-tions. Given the frequent use of DMSO in biochemical and biophysical assays, it is desirable to understand the influence of DMSO concentration on the dissociation or unfolding behavior of proteins. In this study, the effects of DMSO on the structure and interac-tions of avidin and Mycobacterium tuberculosis (Mtb) CYP142A1 were assessed through collision-induced dissociation (CID) and collision-induced unfolding (CIU) as monitored by nanoelectrospray ionization-ion mobility-mass spectrometry (nESI-IM-MS)...
August 13, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28801345/molecular-basis-for-increased-susceptibility-of-indigenous-north-americans-to-seropositive-rheumatoid-arthritis
#5
Stephen W Scally, Soi-Cheng Law, Yi Tian Ting, Jurgen van Heemst, Jeremy Sokolove, Aaron J Deutsch, E Bridie Clemens, Antonis K Moustakas, George K Papadopoulos, Diane van der Woude, Irene Smolik, Carol A Hitchon, David B Robinson, Elizabeth D Ferucci, Charles N Bernstein, Xiaobo Meng, Vidyanand Anaparti, Tom Huizinga, Katherine Kedzierska, Hugh H Reid, Soumya Raychaudhuri, René E Toes, Jamie Rossjohn, Hani El-Gabalawy, Ranjeny Thomas
OBJECTIVE: The pathogenetic mechanisms by which HLA-DRB1 alleles are associated with anticitrullinated peptide antibody (ACPA)-positive rheumatoid arthritis (RA) are incompletely understood. RA high-risk HLA-DRB1 alleles are known to share a common motif, the 'shared susceptibility epitope (SE)'. Here, the electropositive P4 pocket of HLA-DRB1 accommodates self-peptide residues containing citrulline but not arginine. HLA-DRB1 His/Phe13β stratifies with ACPA-positive RA, while His13βSer polymorphisms stratify with ACPA-negative RA and RA protection...
August 11, 2017: Annals of the Rheumatic Diseases
https://www.readbyqxmd.com/read/28798979/mucosa-associated-invariant-t-cells-infiltrate-hepatic-metastases-in-patients-with-colorectal-carcinoma-but-are-rendered-dysfunctional-within-and-adjacent-to-tumor-microenvironment
#6
Christopher R Shaler, Mauro E Tun-Abraham, Anton I Skaro, Khashayarsha Khazaie, Alexandra J Corbett, Tina Mele, Roberto Hernandez-Alejandro, S M Mansour Haeryfar
Mucosa-associated invariant T (MAIT) cells are innate-like T lymphocytes that are unusually abundant in the human liver, a common site of colorectal carcinoma (CRC) metastasis. However, whether they contribute to immune surveillance against colorectal liver metastasis (CRLM) is essentially unexplored. In addition, whether MAIT cell functions can be impacted by chemotherapy is unclear. These are important questions given MAIT cells' potent immunomodulatory and inflammatory properties. Herein, we examined the frequencies and functions of peripheral blood, healthy liver tissue, tumor-margin and tumor-infiltrating MAIT cells in 21 CRLM patients who received no chemotherapy, FOLFOX, or a combination of FOLFOX and Avastin before they underwent liver resection...
August 10, 2017: Cancer Immunology, Immunotherapy: CII
https://www.readbyqxmd.com/read/28798415/epicatechin-oligomers-longer-than-trimers-have-anti-cancer-activities-but-not-the-catechin-counterparts
#7
Kohki Takanashi, Manato Suda, Kiriko Matsumoto, Chisato Ishihara, Kazuya Toda, Koichiro Kawaguchi, Shogo Senga, Narumi Kobayashi, Mikihiro Ichikawa, Miyuki Katoh, Yasunao Hattori, Sei-Ichi Kawahara, Koji Umezawa, Hiroshi Fujii, Hidefumi Makabe
Since procyanidins (oligomeric catechin or epicatechin) were reported to exhibit health benefits, much attention has been paid to the synthesis of these compounds, especially those that are longer than trimers. In the present study, syntheses of cinnamtannin A3 (epicatechin pentamer), A4 (epicatechin hexamer), catechin tetramer, pentamer, arecatannin A2 (epicatechin-epicatechin-epicatechin-catechin) and A3 (epicatechin-epicatechin-epicatechin-epicatechin-catechin) were achieved. The key reaction was a Lewis acid mediated equimolar condensation...
August 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28794233/characterization-of-mycobacterium-tuberculosis-specific-cells-using-mhc-class-ii-tetramers-reveals-phenotypic-differences-related-to-hiv-infection-and-tuberculosis-disease
#8
Natalie Strickland, Tracey L Müller, Natacha Berkowitz, Rene Goliath, Mary N Carrington, Robert J Wilkinson, Wendy A Burgers, Catherine Riou
A major challenge for the development of an effective vaccine against tuberculosis (TB) is that the attributes of protective CD4(+) T cell responses are still elusive for human TB. Infection with HIV type 1 is a major risk factor for TB, and a better understanding of HIV-induced alterations of Mycobacterium tuberculosis-specific CD4(+) T cells that leads to failed host resistance may provide insight into protective T cell immunity to TB. A total of 86 participants from a TB-endemic setting, either HIV-infected or uninfected and with latent or active TB (aTB), were screened using M...
August 9, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/28789935/tetramer-as-efficient-structural-mode-for-organizing-antioxidative-carboxylic-acids-the-case-in-inhibiting-dna-oxidation
#9
Ri Zhou, Zai-Qun Liu
To overcome the problem on the relationship of antioxidative effect with the branch number in a tetramer, we herein designed a series of antioxidants with pentaerythritol, glycerol, and ethylene glycol as the cores, and gallic, ferulic, caffeic, and p-hydroxybenzoic acids as the antioxidative moieties. In the case of DNA oxidation mediated by 2,2'-azobis(2-amidinopropane hydrochloride, AAPH), it was found that the stoichiometric factor (n) of a carboxylic acid increased rapidly when the acid was esterified with ethylene glycol, glycerol, and pentaerythritol to form a dimer, trimer, and tetramer, respectively...
August 5, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28783324/a-noncanonical-binding-site-in-the-evh1-domain-of-vasp-regulates-its-interactions-with-the-proline-rich-region-of-zyxin
#10
Lucila Andrea Acevedo, Alexander Ian Greenwood, Linda K Nicholson
Vasodilator-Stimulated Phosphoprotein, VASP, is a processive actin polymerase with roles in the control of cell shape and cell migration. Through interaction with the cytoskeletal adaptor protein Zyxin, VASP can localize to damaged stress fibers where it serves to repair and reinforce these structures. VASP localization is mediated by its N-terminal Ena/VASP Homology domain (EVH1), which binds to the motif (W/F)PxφP (most commonly occurring as FPPPP) found in cytoskeletal proteins such as vinculin, lamellipodin, and Zyxin...
August 7, 2017: Biochemistry
https://www.readbyqxmd.com/read/28782560/glutamate-promotes-ssb-protein-protein-interactions-via-intrinsically-disordered-regions
#11
Alexander G Kozlov, Min Kyung Shinn, Elizabeth A Weiland, Timothy M Lohman
E. coli single strand (ss) DNA binding protein (SSB) is an essential protein that binds to ssDNA intermediates formed during genome maintenance. SSB homotetramers bind ssDNA in several modes that differ in occluded site size and cooperativity. High "unlimited" cooperativity is associated with the 35 site size ((SSB)35) mode at low [NaCl], whereas the 65 site size ((SSB)65) mode formed at higher [NaCl] (> 200mM), where ssDNA wraps completely around the tetramer, displays "limited" cooperativity forming dimers of tetramers...
August 3, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28777576/a-chiral-thiophene-sulfonamide-a-challenge-for-voa-calculations
#12
Joanna E Rode, Jan Cz Dobrowolski, Krzysztof Lyczko, Aleksandra Wasiewicz, Dorota Kaczorek, Robert Kawęcki, Grzegorz Zajac, Malgorzata Baranska
Two enantiomers of 2-methyl-N-(1-thien-2-ylethyl)propane-2-sulfonamide (TSA), were synthesized and their VCD, ROA, IR, and Raman spectra were registered. The solved (S)-TSA X-ray structure shows a disorder connected to the presence of two TSA conformers differing by a slight rotation of the thiophene ring. Two molecules in the units cell of monoclinic P21 crystal form a net of NH∙∙∙OS and C*H∙∙∙OS hydrogen bonds. Out of a series of computational levels tested to interpret the spectra, the B3LYP functional combined with the def2TZVP basis set satisfactorily reproduces the experimental VCD and ROA spectra...
August 4, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28776372/structural-stability-of-the-coiled-coil-domain-of-tumor-susceptibility-gene-tsg-101
#13
Jordan T White, Dmitri Toptygin, Randy Cohen, Natalie Murphy, Vincent J Hilser
The Tumor Susceptibility Gene-101 coiled coil domain (TSG101cc) is an integral component of the endosomal maturation machinery and cytokinesis, and also interacts with several transcription factors. The TSG101cc has been crystalized as a homotetramer but is known to interact with two of its binding partners as a heterotrimer. To investigate this apparent discrepancy, we examined the solution thermodynamics of the TSG101cc. Here, we use circular dichroism, differential scanning calorimetry, analytical ultracentrifugation, fluorescence, and structural thermodynamic analysis to investigate the structural stability and the unfolding of the TSG101cc...
August 4, 2017: Biochemistry
https://www.readbyqxmd.com/read/28772018/strategic-construction-of-directly-linked-porphyrin-bodipy-hybrids
#14
Jianxin Song, Lei Xu, Bin Wen, Gakhyun Kim, Taeyeon Kim, Fei Cheng, Mingbo Zhou, Ling Xu, Takayuki Tanaka, Atsuhiro Osuka, Dongho Kim, Bangshao Yin
A powerful and concise synthetic protocol of directly linked porphyrin-BODIPY hybrids has been demonstrated, which consists of condensation of directly linked meso-pyrroyl NiII-porphyrin with arylaldehyde, oxidation with p-chloranil, and complexation with BF3*Et2O. Synthesized hybrids include porphyrin dimer 6Ni, trimers 8Ni, 9Ni, tetramer 12Ni, pentamer 16Ni, hexamer 13Ni, and nonamers 17Ni and 18Ni. The structures of 6Ni, 9Ni and 12Ni were unambiguously confirmed by X-ray diffraction analysis. Some NiII-porphyrins were effectively converted to the corresponding ZnII-porphryins...
August 2, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28767229/photochemical-water-splitting-with-organomanganese-complexes
#15
Karthika J Kadassery, Suman Kr Dey, Anthony F Cannella, Roshaan Surendhran, David C Lacy
Certain organometallic chromophores with water-derived ligands, such as the known [Mn(CO)3(μ3-OH)]4 (1) tetramer, drew our attention as possible platforms to study water-splitting reactions. Herein, we investigate the UV irradiation of various tricarbonyl organomanganese complexes, including 1, and demonstrate that dihydrogen, CO, and hydrogen peroxide form as products in a photochemical water-splitting decomposition reaction. The organic and manganese-containing side products are also characterized. Labeling studies with (18)O-1 suggest that the source of oxygen atoms in H2O2 originates from free water that interacts with 1 after photochemical dissociation of CO (1-CO) constituting the oxidative half-reaction of water splitting mediated by 1...
August 2, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28765875/quantum-dot-pmhc-multimers-vs-phycoerythrin-pmhc-tetramers-for-identification-of-hla-a-0201-restricted-phbv-core-antigen18-27-specific-t-cells
#16
Jianmeng Zhu, Yong Huang, Jing Su, Jian He, Yating Yu, Yongxiang Zhao, Xiaoling Lu
Detection of human leukocyte antigens-A2-restricted p-hepatitis B virus (HBV) core antigen‑specific cytotoxic T lymphocytes (CTLs) is important in the study of HBV immunopathogenesis and vaccine design. Currently, major histocompatibility complex (MHC) class I/peptide‑(p) MHCI tetramers are considered the optimal tools to detect antigen‑specific CTLs. However, the MHC‑tetramer technique also has certain drawbacks and is under continuous development. The quantum dot (QD) bioconjugates nanotechnology with its unique inorganic‑biological properties has been developing fast...
August 1, 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28760960/oligomerization-of-the-tetramerization-domain-of-p53-probed-by-two-and-three-color-single-molecule-fret
#17
Hoi Sung Chung, Fanjie Meng, Jae-Yeol Kim, Kevin McHale, Irina V Gopich, John M Louis
We describe a method that combines two- and three-color single-molecule FRET spectroscopy with 2D FRET efficiency-lifetime analysis to probe the oligomerization process of intrinsically disordered proteins. This method is applied to the oligomerization of the tetramerization domain (TD) of the tumor suppressor protein p53. TD exists as a monomer at subnanomolar concentrations and forms a dimer and a tetramer at higher concentrations. Because the dissociation constants of the dimer and tetramer are very close, as we determine in this paper, it is not possible to characterize different oligomeric species by ensemble methods, especially the dimer that cannot be readily separated...
August 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28760744/proanthocyanidin-trimer-gallate-modulates-lipid-deposition-and-fatty-acid-desaturation-in-caenorhabditis-elegans
#18
Yu Nie, Brad Littleton, Thomas Kavanagh, Vincenzo Abbate, Sukhvinder S Bansal, David Richards, Peter Hylands, Stephen R Stürzenbaum
The incidence of obesity is rising at an alarming rate. Despite its recognition as an urgent healthcare concern, obesity remains largely an unsolved medical problem. A comprehensive screen for functional dietary phytochemicals identified proanthocyanidins as putative targets to ameliorate obesity. A full-scale purification of oligomeric proanthocyanidins (OPCs) derived from grape seed extract, yielded pure OPC dimer, trimer, tetramer, and their gallates (pOPCs). Forward chemical screening conducted in Caenorhabditis elegans suggested that pOPCs reduced the activity of lipase in vitro and triglyceride storage capacity in vivo Proanthocyanidin trimer gallate in particular modified lipid desaturation in C...
July 31, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28759334/b-cell-tetramer-development-for-veterinary-vaccinology
#19
Michael C Rahe, Kevin L Gustafson, Michael P Murtaugh
Immunological memory is elicited after either vaccination or natural exposure to a pathogen and is essential for protection against re-exposure. Despite its critical importance, the ability to interrogate the veterinary animal memory immune response has long been hindered by a paucity of tools to assess immunological memory. As a result, the evaluation and analysis of protective immune responses that predict immune protection in food and fiber animals and facilitate vaccine development are obstructed. To fill this gap in knowledge in swine, we created a B cell tetramer to porcine reproductive and respiratory syndrome virus (PRRSV) nonstructural protein 7 (nsp7) to efficiently and effectively investigate the memory B cell response, a hallmark of anti-viral immunity...
July 31, 2017: Viral Immunology
https://www.readbyqxmd.com/read/28757619/crystal-structure-of-a-pseudomonas-malonate-decarboxylase-holoenzyme-hetero-tetramer
#20
Riyaz Maderbocus, Blanche L Fields, Keith Hamilton, Shukun Luo, Timothy H Tran, Lars E P Dietrich, Liang Tong
Pseudomonas species and other aerobic bacteria have a biotin-independent malonate decarboxylase that is crucial for their utilization of malonate as the sole carbon and energy source. The malonate decarboxylase holoenzyme contains four subunits, having an acyl-carrier protein (MdcC subunit) with a distinct prosthetic group, as well as decarboxylase (MdcD-MdcE) and acyl-carrier protein transferase (MdcA) catalytic activities. Here we report the crystal structure of a Pseudomonas malonate decarboxylase hetero-tetramer, as well as biochemical and functional studies based on the structural information...
July 31, 2017: Nature Communications
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