Use of Recombinant Entamoeba histolytica Cysteine Proteinase 1 To Identify a Potent Inhibitor of Amebic Invasion in a Human Colonic Model

Mele&#x301,ndez-Lo&#x301,pez, Samuel G.,Herdman, Scott,Hirata, Ken,Choi, Min-Ho,Choe, Youngchool,Craik, Charles,Caffrey, Conor R.,Hansell, Elisabeth,Chá,vez-Mungui&#x301,a, Bibiana,Chen, Yen Tin American Society for Microbiology 2007 EUKARYOTIC CELL Vol.6 No.7

<B>ABSTRACT</B><P>Cysteine proteinases are key virulence factors of the protozoan parasite <I>Entamoeba histolytica</I>. We have shown that cysteine proteinases play a central role in tissue invasion and disruption of host defenses by digesting components of the extracellular matrix, immunoglobulins, complement, and cytokines. Analysis of the <I>E. histolytica</I> genome project has revealed more than 40 genes encoding cysteine proteinases. We have focused on <I>E. histolytica</I> cysteine proteinase 1 (EhCP1) because it is one of two cysteine proteinases unique to invasive <I>E. histolytica</I> and is highly expressed and released. Recombinant EhCP1 was expressed in <I>Escherichia coli</I> and refolded to an active enzyme with a pH optimum of 6.0. We used positional-scanning synthetic tetrapeptide combinatorial libraries to map the specificity of the P1 to P4 subsites of the active site cleft. Arginine was strongly preferred at P2, an unusual specificity among clan CA proteinases. A new vinyl sulfone inhibitor, WRR483, was synthesized based on this specificity to target EhCP1. Recombinant EhCP1 cleaved key components of the host immune system, C3, immunoglobulin G, and pro-interleukin-18, in a time- and dose-dependent manner. EhCP1 localized to large cytoplasmic vesicles, distinct from the sites of other proteinases. To gain insight into the role of secreted cysteine proteinases in amebic invasion, we tested the effect of the vinyl sulfone cysteine proteinase inhibitors K11777 and WRR483 on invasion of human colonic xenografts. The resultant dramatic inhibition of invasion by both inhibitors in this human colonic model of amebiasis strongly suggests a significant role of secreted amebic proteinases, such as EhCP1, in the pathogenesis of amebiasis.</P>

The multiple merger assembly of a hyperluminous obscured quasar at redshift 4.6

Di&#x301,az-Santos, T.,Assef, R. J.,Blain, A. W.,Aravena, M.,Stern, D.,Tsai, C.-W.,Eisenhardt, P.,Wu, J.,Jun, H. D.,Dibert, K.,Inami, H.,Lansbury, G.,Leclercq, F. American Association for the Advancement of Scienc 2018 Science Vol.362 No.6418

<P><B>Mergers drive a powerful dusty quasar</B></P><P>Massive galaxies in the early Universe host supermassive black holes at their centers. When material falls toward the black hole, it releases energy and is observed as a quasar. Astronomers found a population of powerful distant quasars that are obscured by dust, but it has been unclear how they are formed. Díaz-Santos <I>et al.</I> observed the dust-obscured quasar WISE J224607.56-052634.9 at submillimeter wavelengths, finding three small companion galaxies connected to the quasar by bridges of gas and dust. They inferred that galaxy mergers can provide both the raw material to power a quasar and large quantities of dust to obscure it.</P><P><I>Science</I>, this issue p. 1034</P><P>Galaxy mergers and gas accretion from the cosmic web drove the growth of galaxies and their central black holes at early epochs. We report spectroscopic imaging of a multiple merger event in the most luminous known galaxy, WISE J224607.56−052634.9 (W2246−0526), a dust-obscured quasar at redshift 4.6, 1.3 billion years after the Big Bang. Far-infrared dust continuum observations show three galaxy companions around W2246−0526 with disturbed morphologies, connected by streams of dust likely produced by the dynamical interaction. The detection of tidal dusty bridges shows that W2246−0526 is accreting its neighbors, suggesting that merger activity may be a dominant mechanism through which the most luminous galaxies simultaneously obscure and feed their central supermassive black holes.</P>

Brassinosteroid Biosynthesis Is Modulated via a Transcription Factor Cascade of COG1, PIF4, and PIF5

Wei, Zhuoyun,Yuan, Tong,Tarkowsks&#x30c,á,, Danus&#x30c,e,Kim, Jeongsik,Nam, Hong Gil,Novs&#x30c,á,r&#x30c,á,k, Onds&#x30c,á,r&#x30c,ej,He, Kai,Gou, Xiaoping,Li, Jia American Society of Plant Biologists 2017 Plant Physiology Vol.174 No.2

<P>Brassinosteroids (BRs) are essential phytohormones regulating various developmental and physiological processes during normal growth and development. cog1-3D (cogwheel1-3D) was identified as an activation-tagged genetic modifier of bri1-5, an intermediate BR receptor mutant in Arabidopsis (Arabidopsis thaliana). COG1 encodes a Dof-type transcription factor found previously to act as a negative regulator of the phytochrome signaling pathway. cog1-3D single mutants show an elongated hypocotyl phenotype under light conditions. A loss-of-function mutant or inducible expression of a dominant negative form of COG1 in the wild type results in an opposite phenotype. A BR profile assay indicated that BR levels are elevated in cog1-3D seedlings. Quantitative reverse transcription-polymerase chain reaction analyses showed that several key BR biosynthetic genes are significantly up-regulated in cog1-3D compared with those of the wild type. Two basic helix-loop-helix transcription factors, PIF4 and PIF5, were found to be transcriptionally up-regulated in cog1-3D. Genetic analysis indicated that PIF4 and PIF5 were required for COG1 to promote BR biosynthesis and hypocotyl elongation. Chromatin immunoprecipitation and electrophoretic mobility shift assays indicated that COG1 binds to the promoter regions of PIF4 and PIF5, and PIF4 and PIF5 bind to the promoter regions of key BR biosynthetic genes, such as DWF4 and BR6ox2, to directly promote their expression. These results demonstrated that COG1 regulates BR biosynthesis via up-regulating the transcription of PIF4 and PIF5.</P>

A White-Light-Emitting Molecule: Frustrated Energy Transfer between Constituent Emitting Centers

Park, Sanghyuk,Kwon, Ji Eon,Kim, Se Hun,Seo, Jangwon,Chung, Kyeongwoon,Park, Sun-Young,Jang, Du-Jeon,Medina, Begon&#x303,a Miliá,n,Gierschner, Johannes,Park, Soo Young American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.39

<P>White-light-emitting single molecules are promising materials for use in a new generation of displays and light sources because they offer the possibility of simple fabrication with perfect color reproducibility and stability. To realize white-light emission at the molecular scale, thereby eliminating the detrimental concentration- or environment-dependent energy transfer problem in conventional fluorescent or phosphorescent systems, energy transfer between a larger band-gap donor and a smaller band-gap acceptor must be fundamentally blocked. Here, we present the first example of a concentration-independent ultimate white-light-emitting molecule based on excited-state intramolecular proton transfer materials. Our molecule is composed of covalently linked blue- and orange-light-emitting moieties between which energy transfer is entirely frustrated, leading to the production of reproducible, stable white photo- and electroluminescence.</P>

A Sensing Platform Based on Electrodissolution of a Ag Bipolar Electrode

Chow, Kwok-Fan,Chang, Byoung-Yong,Zaccheo, Brian A.,Mavre&#x301,, Franc&#x327,ois,Crooks, Richard M. American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.27

<P>Here we report a new type of sensing platform that is based on electrodissolution of a metallic bipolar electrode (BPE). When the target DNA binds to the capture probe at the cathodic pole of the BPE, it triggers the oxidation and dissolution of Ag metal present at the anodic pole. The loss of Ag is easily detectable with the naked eye or a magnifying glass and provides a permanent record of the electrochemical history of the electrode. More importantly, the decrease in the length of the BPE can be directly correlated to the number of electrons passing through the BPE and hence to the sensing reaction at the cathode.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-27/ja103715u/production/images/medium/ja-2010-03715u_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja103715u'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja103715u'>ACS Electronic Supporting Info</A></P>

A Bifunctional Molecule as an Artificial Flavin Mononucleotide Cyclase and a Chemosensor for Selective Fluorescent Detection of Flavins

Rhee, Hyun-Woo,Choi, So Jung,Yoo, Sang Ho,Jang, Yong Oh,Park, Hun Hee,Pinto, Rosa Mari&#x301,a,Cameselle, Jose&#x301,Carlos,Sandoval, Francisco J.,Roje, Sanja,Han, Kyungja,Chung, Doo Soo,Suh, Junghun American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.29

<P>Flavins, comprising flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and riboflavin (RF, vitamin B(2)), play important roles in numerous redox reactions such as those taking place in the electron-transfer chains of mitochondria in all eukaryotes and of plastids in plants. A selective chemosensor for flavins would be useful not only in the investigation of metabolic processes but also in the diagnosis of diseases related to flavins; such a sensor is presently unavailable. Herein, we report the first bifunctional chemosensor (PTZ-DPA) for flavins. PTZ-DPA consists of bis(Zn(2+)-dipicolylamine) and phenothiazine. Bis(Zn(2+)-dipicolylamine) (referred to here as XyDPA) was found to be an excellent catalyst in the conversion of FAD into cyclic FMN (riboflavin 4',5'-cyclic phosphate, cFMN) under physiological conditions, even at pH 7.4 and 27 degrees C, with less than 1 mol % of substrate. Utilizing XyDPA's superior function as an artificial FMN cyclase and phenothiazine as an electron donor able to quench the fluorescence of an isoalloxazine ring, PTZ-DPA enabled selective fluorescent discrimination of flavins (FMN, FAD, and RF): FAD shows ON(+), FMN shows OFF(-), and RF shows NO(0) fluorescence changes upon the addition of PTZ-DPA. With this selective sensing property, PTZ-DPA is applicable to real-time fluorescent monitoring of riboflavin kinase (RF to FMN), alkaline phosphatase (FMN to RF), and FAD synthetase (FMN to FAD).</P>

An NADPH-Oxidase/Polyamine Oxidase Feedback Loop Controls Oxidative Burst Under Salinity

Ge&#x301,mes, Katalin,Kim, Yu Jung,Park, Ky Young,Moschou, Panagiotis N.,Andronis, Efthimios,Valassaki, Chryssanthi,Roussis, Andreas,Roubelakis-Angelakis, Kalliopi A. American Society of Plant Biologists 2016 Plant Physiology Vol.172 No.3

<P>The apoplastic polyamine oxidase (PAO) catalyzes the oxidation of the higher polyamines spermidine and spermine, contributing to hydrogen peroxide (H2O2) accumulation. However, it is yet unclear whether apoplastic PAO is part of a network that coordinates the accumulation of reactive oxygen species (ROS) under salinity or if it acts independently. Here, we unravel that NADPH oxidase and apoplastic PAO cooperate to control the accumulation of H2O2 and superoxides (O-2(center dot-)) in tobacco (Nicotiana tabacum). To examine to what extent apoplastic PAO constitutes part of a ROS-generating network, we examined ROS accumulation in guard cells of plants overexpressing or down-regulating apoplastic PAO (lines S2.2 and A2, respectively) or down-regulating NADPH oxidase (line AS-NtRbohD/F). The H2O2-specific probe benzene sulfonyl-H2O2 showed that, under salinity, H2O2 increased in S2.2 and decreased in A2 compared with the wild type. Surprisingly, the O-2(center dot-)-specific probe benzene sulfonyl-So showed that O-2(center dot-) levels correlated positively with that of apoplastic PAO (i.e. showed high and low levels in S2.2 and A2, respectively). By using AS-NtRbohD/F lines and a pharmacological approach, we could show that H2O2 and O-2(center dot-) accumulation at the onset of salinity stress was dependent on NADPH oxidase, indicating that NADPH oxidase is upstream of apoplastic PAO. Our results suggest that NADPH oxidase and the apoplastic PAO form a feed-forward ROS amplification loop, which impinges on oxidative state and culminates in the execution of programmed cell death. We propose that the PAO/NADPH oxidase loop is a central hub in the plethora of responses controlling salt stress tolerance, with potential functions extending beyond stress tolerance.</P>

Probing Quantum Confinement within Single Core–Multishell Nanowires

Marti&#x301,nez-Criado, Gema,Homs, Alejandro,Ale&#x301,n, Benito,Sans, Juan A.,Segura-Ruiz, Jaime,Molina-Sá,nchez, Alejandro,Susini, Jean,Yoo, Jinkyoung,Yi, Gyu-Chul American Chemical Society 2012 NANO LETTERS Vol.12 No.11

<P>Theoretically core–multishell nanowires under a cross-section of hexagonal geometry should exhibit peculiar confinement effects. Using a hard X-ray nanobeam, here we show experimental evidence for carrier localization phenomena at the hexagon corners by combining synchrotron excited optical luminescence with simultaneous X-ray fluorescence spectroscopy. Applied to single coaxial n-GaN/InGaN multiquantum-well/p-GaN nanowires, our experiment narrows the gap between optical microscopy and high-resolution X-ray imaging and calls for further studies on the underlying mechanisms of optoelectronic nanodevices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-11/nl303178u/production/images/medium/nl-2012-03178u_0007.gif'></P>

Antifungal Nanocomposites Inspired by Titanate Nanotubes for Complete Inactivation of <i>Botrytis cinerea</i> Isolated from Tomato Infection

Rodri&#x301,guez-Gonzá,lez, V.,Domi&#x301,nguez-Espi&#x301,ndola, R. B.,Casas-Flores, S.,Patro&#x301,n-Soberano, O. A.,Camposeco-Solis, R.,Lee, S.-W. American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.46

<P>Antifungal silver nanocomposites inspired by titanate nanotubes (AgTNTs) were successfully evaluated for the effective inactivation of the phytopathogenic fungus Botrytis cinerea within 20 min. One-dimensional H2Ti3O7 nanotubes functionalized with silver nanoparticles (AgNPs) exhibit unique surface and antifungal properties for the photoinactivation of B. cinerea. Nanostructured titanates were synthesized by the eco-friendly, practical, microwave-induced, hydrothermal method followed by a highly monodispersive AgNP UV-photo deposition. Protonated nanotubes of similar to 11 nm in diameter and four-layers displayed high surface areas, 300 m(2)/g, with a size functionalization of 5 nm for the AgNPs. UV-vis DRS and XPS allowed the characterization and/or quantification of surface reactive species and cytotoxic silver species such as Ag degrees, Ag+. The effective biocidal properties of the nanocomposites were confirmed by using the well-known Gram-negative bacteria Escherichia coli, and then proceeding to the effective inactivation of the phytopathogenic fungus under visible light. The photo assisted inactivation mechanism was examined by HAADF-STEM, HRTEM, and FESEM electronic microscopies. A plasmalemma invagination due to oxidative stress caused by reactive oxygen, silver cytotoxicity species, and AgTNT sharp morphology damage expands the conidia to induce the cell death. The impact of the eco-friendly inactivation is significant because of the ease with which it is carried out and the possibility of being performed in situ with plants like tomato and grapes, which are ranked among the most valuable agricultural products worldwide.</P>

Fluorescence Enhancement of a Microbial Rhodopsin via Electronic Reprogramming

Mari&#x301,n, Mari&#x301,a del Carmen,Agathangelou, Damianos,Orozco-Gonzalez, Yoelvis,Valentini, Alessio,Kato, Yoshitaka,Abe-Yoshizumi, Rei,Kandori, Hideki,Choi, Ahreum,Jung, Kwang-Hwan,Haacke, Stefan American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.1

<P>The engineering of microbial rhodopsins with enhanced fluorescence is of great importance in the expanding field of optogenetics. Here we report the discovery of two mutants (W76S/Y179F and L83Q) of a sensory rhodopsin from the cyanobacterium <I>Anabaena</I> PCC7120 with opposite fluorescence behavior. In fact, while W76S/Y179F displays, with respect to the wild-type protein, a nearly 10-fold increase in red-light emission, the second is not emissive. Thus, the W76S/Y179F, L83Q pair offers an unprecedented opportunity for the investigation of fluorescence enhancement in microbial rhodopsins, which is pursued by combining transient absorption spectroscopy and multiconfigurational quantum chemistry. The results of such an investigation point to an isomerization-blocking electronic effect as the direct cause of instantaneous (subpicosecond) fluorescence enhancement.</P> [FIG OMISSION]</BR>