Structure-function dissection of Myxococcus xanthus CarD N-terminal domain, a defining member of the CarD-CdnL-TRCF family of RNA polymerase interacting proteins

© 2015 Bernal-Bernal et al. Two prototypes of the large CarD-CdnL-TRCF family of bacterial RNA polymerase (RNAP)-binding proteins, Myxococcus xanthus CarD and CdnL, have distinct functions whose molecular basis remain elusive. CarD, a global regulator linked to the action of several extracytoplasmic function (ECF) σ-factors, binds to the RNAP β subunit (RNAP-β) and to protein CarG via an N-terminal domain, CarDNt, and to DNA via an intrinsically unfolded C-terminal domain resembling eukaryotic high-mobility-group A (HMGA) proteins. CdnL, a CarDNt-like protein that is essential for cell viability, is implicated in σA-dependent rRNA promoter activation and interacts with RNAP-β but not with CarG. While the HMGA-like domain of CarD by itself is inactive, we find that CarDNt has low but observable ability to activate ECF σ-dependent promoters in vivo, indicating that the C-terminal DNA-binding domain is required to maximize activity. Our structure-function dissection of CarDNt reveals an N-terminal, five-stranded β-sheet Tudor-like domain, CarD1-72, whose structure and contacts with RNAP-β mimic those of CdnL. Intriguingly, and in marked contrast to CdnL, CarD mutations that disrupt its interaction with RNAP-β did not annul activity. Our data suggest that the CarDNt C-terminal segment, CarD61-179, may be structurally distinct from its CdnL counterpart, and that it houses at least two distinct and crucial function determinants: (a) CarG-binding, which is specific to CarD; and (b) a basic residue stretch, which is also conserved and functionally required in CdnL. This study highlights the evolution of shared and divergent interactions in similar protein modules that enable the distinct activities of two related members of a functionally important and widespread bacterial protein family.Peer Reviewe

Simulación de un concentrador solar de disco parabólico para producción de potencia y enfriamiento

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: En este trabajo se presenta la modelación y simulación de un concentrador solar de disco parabólico para alimentar térmicamente a un sistema de refrigeración por absorción y a un motor Stirling, con diferente eficiencia, acoplado con un sistema de refrigeración por compresión. El enfriamiento producido por este sistema se utiliza para aire acondicionado de una vivienda. El estudio fue realizado mediante balances de energía y de masa, en cada componente de los sistemas de refrigeración y del sistema solar. La transferencia de calor por convección y por radiación también fueron considerados. Los resultados muestran que el colector solar alcanza eficiencia térmica de hasta 0.82 para relación de concentración de 100. El concentrador solar produce hasta 1.3 kW. En tanto que el sistema completo puede producir enfriamiento de 2.3 kW y 0.47 kW por el sistema de compresión y el de absorción respectivamente. La potencia de la bomba de la disolución es hasta 20 veces menor que la potencia requerida por el compresor del sistema de compresión.ABSTRACT: This paper presents the dish solar collector modeling and simulation for thermally driving an absorption refrigeration system and a Stirling engine, with different efficiency, coupled with a compression refrigeration system. The cooling produced by the system is used for home air conditioning. The study by means energy and mass balances, in each component of the cooling systems and the solar system was carried out. The Convection and radiation heat transfer also has been considered. The results show that the solar collector reaches thermal efficiency of up to 0.82 for a concentration ratio of 100. The solar concentrator produces up to 1.3 kW. While the complete system 2.3 kW and 0.47 kW of cooling by the compression and absorption system respectively can produce. The power of the solution pump is up to 20 times less than the power required by the compressor of the compression system.info:eu-repo/semantics/publishedVersio

Rapid decrease in titer and breadth of neutralizing anti-HCV antibodies in HIV/HCV-coinfected patients who achieved SVR

The main targets for neutralizing anti-hepatitis C virus (HCV) antibodies (HCV-nAbs) are the E1 and E2 envelope glycoproteins. We have studied the characteristics of HCV-nAbs through a retrospective study involving 29 HIV/HCV-coinfected patients who achieved sustained virological response (SVR) with pegIFNα+ribavirin anti-HCV therapy. Plasma samples at baseline and week 24 after SVR were used to perform neutralization assays against fve JFH1-based HCV recombinant viruses coding for E1 and E2 from genotypes 1a (H77), 1b (J4), 2a (JFH1), 3a (S52) and 4a (ED43). At baseline, the majority of plasma samples neutralized 1a, 1b, 2a, and 4a, but not 3a, genotypes. Twenty-four weeks following SVR, most neutralizing titers declined substantially. Furthermore, titers against 3a and 2a were not detected in many patients. Plasma samples with high HCV-nAb titers neutralized all genotypes, and the highest titers at the starting point correlated with the highest titers at week 24 after SVR. In conclusion, high titers of broad-spectrum HCV-nAbs were detected in HIV/HCV-coinfected individuals, however, those titers declined soon after SVRThis study was supported by grants from Instituto de Salud Carlos III (ISCIII; grant numbers PI14/01094 and PI17/00657 to JB, PI17/00903 to JGG, PI14CIII/00011 and PI17CIII/00003 to SR) and Ministerio de Sanidad, Servicios Sociales e Igualdad (grant number EC11-241). Te study was also funded by the RD16CIII/0002/0002, RD16/0025/0018, and RD16/0025/0017 projects as part of the Plan Nacional R+D+I and co-funded by ISCIII- Subdirección General de Evaluación and the Fondo Europeo de Desarrollo Regional (FEDER

Cytomegalovirus infection in HIV-infected patients in the era of combination antiretroviral therapy

Background: Cytomegalovirus infection dramatically decreased with the introduction of antiretroviral therapy. Whether incidence, clinical characteristics and prognosis of cytomegalovirus in HIV infected patients, has changed over time is. scarcely known. Methods: Retrospective single-center study. Patients included in this study were all HIV infected patients that went to our center for any disease, and were diagnosed with cytomegalovirus, during the period 2004-2015. epidemiological, clinical and laboratory patients variables were collected in a clinical database. Clinical characteristics, incidence of cytomegalovirus and predictors of mortality during the study were assessed. Results were considered statistically significant when p < 0.05. All statistical analyses were calculated by SPSS version 20.0 (Chicago, IL,USA). Results: Fifty-six cases of cytomegalovirus infection, in HIV infected patients were identified during the study period (incidence rate-1.7 cases per 1000 persons/year). The most frequent presentation was systemic illness in 43% of cases. Of note,no patients presented with ophthalmic manifestations. The 30-days mortality was 18%. Predictors of mortality were, in the univariate analysis, admission to the intensive care unit OR 32.4 (3.65-287.06) p = 0.0001, and mechanic ventilation 84 OR (8.27-853.12) p = 0.0001, and ART OR 4.1 (0.97-17.31) p = 0.044. These variables were assessed by multivariate analysis, and only mechanical ventilation was statistically significant (p < 0.05) CONCLUSION: Incidence of cytomegalovirus infection was higher than described in the antiretroviral therapy era. Clinical presentation has changed. Mechanic ventilation predicted mortality

Conformationally restricted PACAP27 analogues incorporating type II/II′ IBTM β-Turn mimetics. Synthesis, NMR structure determination, and binding affinity

To probe the importance of a proposed β-turn within residues S9-R12 of PACAP for recognition by VIP/PACAP receptors, compounds 1 and 2, two conformationally restricted analogues of PACAP27 incorporating respectively (S)- or (R)-IBTM as type II or II′ β-turn dipeptide mimetic at the Y10-S11 position, were synthesized. According to 1H NMR conformational analyses in aqueous solution and 30% TFE, both PACAP27 and the [S-IBTM10,11]PACAP27 analogue 1 adopt similar ordered structures. PACAP27 shows an N-terminal disordered region (residues H1-F6) and an α-helical conformation within segment T7–L27. For residues S9–R12, our data seem more compatible with a segment of the α-helix than with the β-turn previously proposed for this fragment. In compound 1 the α-helix, also spanning T7–L27 residues, appears slightly distorted at the N-terminus relative to the native peptide. Although this distortion could lead to the marked decrease in binding affinity of this compound at the VIP/PACAP receptors, the lack of the Y10 side chain in analogues 1 and 2 could also significantly affect the binding of these compounds.Work at the Instituto de Quı́mica Médica and Universidad de Navarra was supported by CICYT (SAF 97 0030 and SAF 2000-0147), Fundación La Caixa (97/022) and Comunidad Autónoma de Madrid (08.5/0006/1998). Work at the Instituto de Estructura de la Materia was supported by DGICYT (PB98-0677) and the European Union (CEE B104-97-2086). Work at the Universidad de Barcelona was supported by Generalitat de Catalunya (CERBA). C.M.S. and M.M.-M. are recipients of a pre-doctoral and a post-doctoral fellowship, respectively, from the Comunidad Autónoma de Madrid, Spain. E.de O. is a post-doctoral fellow of Fundació Bosch i Gimpera, Universitat de Barcelona, Spain

Helical peptides from VEGF and Vammin hotspots for modulating the VEGF-VEGFR interaction

The design, synthesis, conformational studies and binding affinity for VEGF receptors of a collection of linear and cyclic peptide analogues of the N-terminal α-helix fragments 13-25 of VEGF and 1-13 of Vammin are described. Linear 13(14)-mer peptides were designed with the help of an AGADIR algorithm and prepared following peptide solid-phase synthetic protocols. Cyclic peptide derivatives were prepared on-resin from linear precursors with conveniently located Glu and Lys residues, by the formation of amide linkages. Conformational analysis, CD and NMR, showed that most synthesized peptides have a clear tendency to be structured as α-helices in solution. Some of the peptides were able to bind a VEGFR-1 receptor with moderate affinity. In addition to the described key residues (Phe17, Tyr21 and Tyr25), Val14 and Val20 seem to be relevant for affinity.Peer Reviewe

Cylindrospermopsin-microcystin-LR combinations may induce genotoxic and histopathological damage in rats

Cylindrospermopsin (CYN) and microcystins (MC) are cyanotoxins that can occur simultaneously in contaminated water and food. CYN/MC-LR mixtures previously investigated in vitro showed an induction of micronucleus (MN) formation only in the presence of the metabolic fraction S9. When this is the case, the European Food Safety Authority recommends a follow up to in vivo testing. Thus, rats were orally exposed to 7.5 + 75, 23.7 + 237, and 75 + 750 μg CYN/MC-LR/kg body weight (b.w.). The MN test in bone marrow was performed, and the standard and modified comet assays were carried out to measure DNA strand breaks or oxidative DNA damage in stomach, liver, and blood cells. The results revealed an increase in MN formation in bone marrow, at all the assayed doses. However, no DNA strand breaks nor oxidative DNA damage were induced, as shown in the comet assays. The histopathological study indicated alterations only in the highest dose group. Liver was the target organ showing fatty degeneration and necrotic hepatocytes in centrilobular areas, as well as a light mononuclear inflammatory periportal infiltrate. Additionally, the stomach had flaking epithelium and mild necrosis of epithelial cells. Therefore, the combined exposure to cyanotoxins may induce genotoxic and histopathological damage in vivo.Ministerio de Economía y Competitividad AGL2015-64558-

Mode of action of antimicrobial peptides: long and short amphipathic alpha-helixes use different mechanisms

1 pag. -- 58th Annual Meeting of the Biophysical-Societ