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Md Saddam Hossain, Takahiro Tanaka, Kazuyoshi Takagi, Junji Hayashi, Mamoru Wakayama
In the present study, we purified α-amino acid ester hydrolase (AEH) from cell-free extracts of the Stenotrophomonas maltophilia strain HS1. The approximately 70-kDa AEH from S. maltophilia HS1 (SmAEH) was homogeneous in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analyses, and was present as a tetramer in gel-filtration experiments. The activity of the SmAEH enzyme was then determined by monitoring the synthesis of the antihypertensive agent dipeptide isoleucyl-tryptophan (Ile-Trp) from isoleucyl methyl ester (Ile-OMe) and tryptophan (Trp)...
March 2018: 3 Biotech
Sunil Ghatge, Youri Yang, Woo-Young Song, Tae-Young Kim, Hor-Gil Hur
In the present study, the gene encoding a multicopper oxidase, more precisely a laccase from the thermoalkaliphilic aerobic bacterium Caldalkalibacillus thermarum strain TA2.A1 (CtLac), was cloned and expressed in Escherichia coli. CtLac is a monomeric protein with a molecular weight of 57 kDa as determined by native polyacrylamide gel electrophoresis. The optimum pH and temperature for 2,6-dimethoxyphenol (2,6-DMP) oxidation were 8.0 and 70 °C, respectively. The kinetic constants Km and kcat for 2,6-DMP were of 200 μM and 23 s-1 , respectively...
March 19, 2018: Applied Microbiology and Biotechnology
Chen Katz, Ana Maria Low-Calle, Joshua Choe, Oleg Laptenko, David Tong, Jazmine-Saskya N Joseph-Chowdhury, Francesca Garofalo, Yan Zhu, Assaf Friedler, Carol Prives
The p53 tumor suppressor protein is the most well studied as a regulator of transcription in the nucleus, where it exists primarily as a tetramer. However, there are other oligomeric states of p53 that are relevant to its regulation and activities. In unstressed cells, p53 is normally held in check by MDM2 that targets p53 for transcriptional repression, proteasomal degradation, and cytoplasmic localization. Here we discovered a hydrophobic region within the MDM2 N-terminal domain that binds exclusively to the dimeric form of the p53 C-terminal domain in vitro...
March 16, 2018: Genes & Development
Tales Rocha de Moura, Sina Mozaffari-Jovin, Csaba Zoltán Kibédi Szabó, Jana Schmitzová, Olexandr Dybkov, Constantin Cretu, Michael Kachala, Dmitri Svergun, Henning Urlaub, Reinhard Lührmann, Vladimir Pena
Human nineteen complex (NTC) acts as a multimeric E3 ubiquitin ligase in DNA repair and splicing. The transfer of ubiquitin is mediated by Prp19-a homotetrameric component of NTC whose elongated coiled coils serve as an assembly axis for two other proteins called SPF27 and CDC5L. We find that Prp19 is inactive on its own and have elucidated the structural basis of its autoinhibition by crystallography and mutational analysis. Formation of the NTC core by stepwise assembly of SPF27, CDC5L, and PLRG1 onto the Prp19 tetramer enables ubiquitin ligation...
March 15, 2018: Molecular Cell
Cheleka A M Mpande, One B Dintwe, Munyaradzi Musvosvi, Simbarashe Mabwe, Nicole Bilek, Mark Hatherill, Elisa Nemes, Thomas J Scriba
Background: Maintenance of long-lasting immunity is thought to depend on stem cell memory T cells (TSCM ), which have superior self-renewing capacity, longevity and proliferative potential compared with central memory (TCM ) or effector (TEFF ) T cells. Our knowledge of TSCM derives primarily from studies of virus-specific CD8+ TSCM . We aimed to determine if infection with Mycobacterium tuberculosis ( M. tb ), the etiological agent of tuberculosis, generates antigen-specific CD4+ TSCM and to characterize their functional ontology...
2018: Frontiers in Immunology
Yexin Feng, Zhichang Wang, Jing Guo, Ji Chen, En-Ge Wang, Ying Jiang, Xin-Zheng Li
Proton tunneling is an elementary process in the dynamics of hydrogen-bonded systems. Collective tunneling is known to exist for a long time. Atomistic investigations of this mechanism in realistic systems, however, are scarce. Using a combination of ab initio theoretical and high-resolution experimental methods, we investigate the role played by the protons on the chirality switching of a water tetramer on NaCl(001). Our scanning tunneling spectroscopies show that partial deuteration of the H2 O tetramer with only one D2 O leads to a significant suppression of the chirality switching rate at a cryogenic temperature (T), indicating that the chirality switches by tunneling in a concerted manner...
March 14, 2018: Journal of Chemical Physics
Shotaro Hoshino, Chin Piow Wong, Masahiro Ozeki, Huiping Zhang, Fumiaki Hayashi, Takayoshi Awakawa, Shumpei Asamizu, Hiroyasu Onaka, Ikuro Abe
New polycyclic tetramate macrolactams, Umezawamides A (1) and B (2) were isolated from a combined-culture of Umezawaea sp. RD066910 and mycolic-acid containing bacterium Tsukamurella pulmonis TP-B0596. Their planar structures and partial stereochemistries were determined based on the spectroscopic analysis, MMFF conformational search, and ECD calculations. Umezawamides are the first secondary metabolites isolated from the genus Umezawaea and they exhibited cytotoxicities to P388 murine leukemia cells. Furthermore, umezawamide A (1) showed growth inhibitory activity against Candida albicans...
March 14, 2018: Journal of Antibiotics
Martin Eckardt, Annemarie Greb, Thomas J Simat
Polyphenylsulfone (PPSU) is a new material for the production of baby bottles. PPSU is a polyether plastic formally composed of bisphenol S (BPS) and 4,4'-dihydroxybiphenyl (DHBP), which both have slight endocrine activities in in-vitro-tests. So far, little is known about the presence and the release of potentially hazardous substances from PPSU baby bottles. In our present study, we present a three step approach for the analysis of PPSU starting with polymer characterization in terms of chemical structure, total oligomer content and hydrolytic stability...
March 14, 2018: Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment
Katsuhito Matsuki, Daiki Kato, Masashi Takemoto, Yoshiaki Suzuki, Hisao Yamamura, Susumu Ohya, Hiroshi Takeshima, Yuji Imaizumi
Physiological functions of type 3 ryanodine receptors (RyR3) in smooth muscle (SM) tissues are not well understood, in spite of their wide expression. However, the short isoform of RyR3 is known to be a dominant negative variant (DN-RyR3), which may negatively regulate functions of both RyR2 and full length (FL)-RyR3 by forming hetero-tetramers. Here, functional roles of RyR3 in the regulation of Ca2+ signaling in mesenteric artery SM cells (MASMCs) were examined using RyR3 homozygous knockout mice (RyR3-/- )...
March 14, 2018: American Journal of Physiology. Cell Physiology
Weipeng Mao, Shuaijun Zhan, Bowei Zhu, Da Ma
The preparation of complex functionalized pillar[n]arenes (PA[n]s) is challenging by one-pot co-cyclization or selective deprotection method. We developed a step-growth cyclo-oligomerization method to synthesize functionalized PA[5]s. Dimer, trimer and tetramer were synthesized and characterized. With this new method, we were able to prepare three di- and tetrafunctionalized PA[5]s. By using multi-step synthetic strategy, the chance to form constitutional isomers and other by products was reduced. Therefore, complex tetrafunctionalized PA[5]s were prepared with improved yield...
March 14, 2018: Journal of Organic Chemistry
Aleš Hnízda, Milan Fábry, Takaya Moriyama, Petr Pachl, Michael Kugler, Vítězslav Brinsa, David B Ascher, William L Carroll, Petr Novák, Markéta Žaliová, Jan Trka, Pavlína Řezáčová, Jun J Yang, Václav Veverka
Activating mutations in NT5C2, a gene encoding cytosolic purine 5'-nucleotidase (cN-II), confer chemoresistance in relapsed acute lymphoblastic leukemia. Here we show that all mutants became independent of allosteric effects of ATP and thus constitutively active. Structural mapping of mutations described in patients demonstrates that 90% of leukemia-specific allelles directly affect two regulatory hotspots within the cN-II molecule-the helix A region: residues 355-365, and the intersubunit interface: helix B (232-242) and flexible interhelical loop L (400-418)...
February 25, 2018: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Koen H Hendriks, Sophia G Robinson, Miles N Braten, Christo S Sevov, Brett A Helms, Matthew S Sigman, Shelley D Minteer, Melanie S Sanford
Nonaqueous redox flow batteries (NRFBs) represent an attractive technology for energy storage from intermittent renewable sources. In these batteries, electrical energy is stored in and extracted from electrolyte solutions of redox-active molecules (termed catholytes and anolytes) that are passed through an electrochemical flow cell. To avoid battery self-discharge, the anolyte and catholyte solutions must be separated by a membrane in the flow cell. This membrane prevents crossover of the redox active molecules, while simultaneously allowing facile transport of charge-balancing ions...
February 28, 2018: ACS Central Science
Kwok S Wun, Josephine F Reijneveld, Tan-Yun Cheng, Kristin Ladell, Adam P Uldrich, Jérôme Le Nours, Kelly L Miners, James E McLaren, Emma J Grant, Oscar L Haigh, Thomas S Watkins, Sara Suliman, Sarah Iwany, Judith Jimenez, Roger Calderon, Kattya L Tamara, Segundo R Leon, Megan B Murray, Jacob A Mayfield, John D Altman, Anthony W Purcell, John J Miles, Dale I Godfrey, Stephanie Gras, David A Price, Ildiko Van Rhijn, D Branch Moody, Jamie Rossjohn
The hallmark function of αβ T cell antigen receptors (TCRs) involves the highly specific co-recognition of a major histocompatibility complex molecule and its carried peptide. However, the molecular basis of the interactions of TCRs with the lipid antigen-presenting molecule CD1c is unknown. We identified frequent staining of human T cells with CD1c tetramers across numerous subjects. Whereas TCRs typically show high specificity for antigen, both tetramer binding and autoreactivity occurred with CD1c in complex with numerous, chemically diverse self lipids...
March 12, 2018: Nature Immunology
Xinghao Wang, Jiayi Yao, Siyuan Wang, Xiaoxue Pan, Ruiyang Xiao, Qingguo Huang, Zunyao Wang, Ruijuan Qu
Photodegradation of pollutants is classically explained by reaction with reactive oxygen species. However Mn(III) may also remove pollutants, but direct evidence is actually lacking. Here we investigated the role of soluble Mn(III) on phototransformation of four typical estrogens, namely estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethynylestradiol (EE2), in the presence of Mn(II) and humic acid. Conversion rates of 60.2%, 89.0%, 87.6%, and 80.2% were achieved for E1, E2, E3, and EE2, respectively, after 72 h visible light irradiation...
March 2, 2018: Chemosphere
Natarajan Sathiyamoorthy Venkataramanan, Ambigapathy Suvitha
This study aims to cast light on the nature of interactions and cooperativity that exists in linear dimethyl sulfoxide (DMSO) clusters using dispersion corrected density functional theory. In the linear DMSO, DMSO molecules in the middle of the clusters are bound strongly than at the terminal. The plot of the total binding energy of the clusters vs the cluster size and mean polarizabilities vs cluster size shows an excellent linearity demonstrating the presence of cooperativity effect. The computed incremental binding energy of the clusters remains nearly constant, implying that DMSO addition at the terminal site can happen to form an infinite chain...
March 2, 2018: Journal of Molecular Graphics & Modelling
Simone Culurgioni, Sara Mari, Paola Bonetti, Sara Gallini, Greta Bonetto, Martha Brennich, Adam Round, Francesco Nicassio, Marina Mapelli
Asymmetric cell divisions balance stem cell proliferation and differentiation to sustain tissue morphogenesis and homeostasis. During asymmetric divisions, fate determinants and niche contacts segregate unequally between daughters, but little is known on how this is achieved mechanistically. In Drosophila neuroblasts and murine mammary stem cells, the association of the spindle orientation protein LGN with the stem cell adaptor Inscuteable has been connected to asymmetry. Here we report the crystal structure of Drosophila LGN in complex with the asymmetric domain of Inscuteable, which reveals a tetrameric arrangement of intertwined molecules...
March 9, 2018: Nature Communications
Amandeep Singh, M Vijayan, Umesh Varshney
In addition to the canonical Single Stranded DNA Binding (SSBa) protein, many bacterial species, including mycobacteria, have a paralogous SSBb. The SSBb proteins have not been well characterized. While in B. subtilis, SSBb has been shown to be involved in genetic recombination; in S. coelicolor it mediates chromosomal segregation during sporulation. Sequence analysis of SSBs from mycobacterial species suggests low conservation of SSBb proteins, as compared to the conservation of SSBa proteins. Like most bacterial SSB proteins, M...
January 2018: Tuberculosis
David E Timm, Valorie Bowman, Russell Madsen, Charles Rauch
Protein arginine methyl transferase 5 (PRMT5) is a signaling protein and histone modifying enzyme that is important in many cellular processes, including regulation of eukaryotic gene transcription. Reported here is a 3.7 Å structure of PRMT5, solved in complex with regulatory binding subunit MEP50 (methylosome associated protein 50, WDR77, p44), by single particle (SP) cryo-Electron Microscopy (cryo-EM) using micrographs of particles that are visibly crowded and aggregated. Despite suboptimal micrograph appearance, this cryo-EM structure is in good agreement with previously reported crystal structures of the complex, which revealed a 450 kDa hetero-octameric assembly having internal D2 symmetry...
2018: PloS One
Jingjing Jiang, Hongling Wen, Miaomiao Chi, Ying Liu, Jingxue Liu, Zhankui Cao, Li Zhao, Yanyan Song, Na Liu, Lianli Chi, Zhiyu Wang
Human parainfluenza virus type 3 (hPIV3) is an important respiratory pathogen that causes the majority of viral pneumonia of infants and young children. hPIV3 can infect host cells through the synergistic action of hemagglutinin-neuraminidase (HN) protein and the homotypic fusion (F) protein on the viral surface. HN protein plays a variety of roles during the virus invasion process, such as promoting viral particles to bind to receptors, cleaving sialic acid, and activating the F protein. Crystal structure research shows that HN tetramer adopted a "heads-down" conformation, at least two heads dimmer on flank of the four-helix bundle stalk, which forms a symmetrical interaction interface...
March 7, 2018: Virus Genes
Ziyang Jing, Hui Deng, Junfan Ma, Yanhong Guo, Yaoxian Liang, Rui Wu, Lata A, Zihan Geng, Xiaoyan Qiu, Yue Wang
Podocyte injury occurs during the initiation and development of numerous forms of glomerular disease, and antibodies targeting podocytes have become a biomarker for diagnosis and monitoring treatment response. Accumulating evidence has suggested that immunoglobulin (Ig) is expressed in non‑B lineage cells, including epithelial cancer cells, myeloid cells and several types of normal cells. The main aim of the present study was to ascertain the expression of IgG in human podocytes and to determine its potential role in cellular bioactivity...
March 1, 2018: International Journal of Molecular Medicine
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