The photosynthetic cytochrome c550 from the diatom Phaeodactylum tricornutum

The photosynthetic cytochrome c550 from the marine diatom Phaeodactylum tricornutum has been purified and characterized. Cytochrome c550 is mostly obtained from the soluble cell extract in relatively large amounts. In addition, the protein appeared to be truncated in the last hydrophobic residues of the C-terminus, both in the soluble cytochrome c550 and in the protein extracted from the membrane fraction, as deduced by mass spectrometry analysis and the comparison with the gene sequence. Interestingly, it has been described that the C-terminus of cytochrome c550 forms a hydrophobic finger involved in the interaction with photosystem II in cyanobacteria. Cytochrome c550 was almost absent in solubilized photosystem II complex samples, in contrast with the PsbO and Psb31 extrinsic subunits, thus suggesting a lower affinity of cytochrome c550 for the photosystem II complex. Under iron-limiting conditions the amount of cytochrome c550 decreases up to about 45% as compared to iron-replete cells, pointing to an iron-regulated synthesis. Oxidized cytochrome c550 has been characterized using continuous wave EPR and pulse techniques, including HYSCORE, and the obtained results have been interpreted in terms of the electrostatic charge distribution in the surroundings of the heme centre

The photosynthetic cytochrome c 550 from the diatom Phaeodactylum tricornutum

The photosynthetic cytochrome c550 from the marine diatom Phaeodactylum tricornutum has been purified and characterized. Cytochrome c550 is mostly obtained from the soluble cell extract in relatively large amounts. In addition, the protein appeared to be truncated in the last hydrophobic residues of the C-terminus, both in the soluble cytochrome c550 and in the protein extracted from the membrane fraction, as deduced by mass spectrometry analysis and the comparison with the gene sequence. Interestingly, it has been described that the C-terminus of cytochrome c550 forms a hydrophobic finger involved in the interaction with photosystem II in cyanobacteria. Cytochrome c550 was almost absent in solubilized photosystem II complex samples, in contrast with the PsbO and Psb31 extrinsic subunits, thus suggesting a lower affinity of cytochrome c550 for the photosystem II complex. Under iron-limiting conditions the amount of cytochrome c550 decreases up to about 45% as compared to iron-replete cells, pointing to an iron-regulated synthesis. Oxidized cytochrome c550 has been characterized using continuous wave EPR and pulse techniques, including HYSCORE, and the obtained results have been interpreted in terms of the electrostatic charge distribution in the surroundings of the heme centre.This work was supported by the Spanish Ministry of Economy and Competitiveness (BIO2012-35271, BIO2015-64169-P, MAT2011-23861 and CTQ2015-64486-R) the Andalusian Government (PAIDI BIO-022) and the Aragón Government (Grupo consolidado B-18). All these grants were partially financed by the EU FEDER ProgramPeer reviewe

Conservation of core complex subunits shaped the structure and function of photosystem I in the secondary endosymbiont alga Nannochloropsis gaditana

Photosystem I (PSI) is a pigment protein complex catalyzing the light-driven electron transport from plastocyanin to ferredoxin in oxygenic photosynthetic organisms. Several PSI subunits are highly conserved in cyanobacteria, algae and plants, whereas others are distributed differentially in the various organisms. Here we characterized the structural and functional properties of PSI purified from the heterokont alga Nannochloropsis gaditana, showing that it is organized as a supercomplex including a core complex and an outer antenna, as in plants and other eukaryotic algae. Differently from all known organisms, the N. gaditana PSI supercomplex contains five peripheral antenna proteins, identified by proteome analysis as type-R light-harvesting complexes (LHCr4-8). Two antenna subunits are bound in a conserved position, as in PSI in plants, whereas three additional antennae are associated with the core on the other side. This peculiar antenna association correlates with the presence of PsaF/J and the absence of PsaH, G and K in the N. gaditana genome and proteome. Excitation energy transfer in the supercomplex is highly efficient, leading to a very high trapping efficiency as observed in all other PSI eukaryotes, showing that although the supramolecular organization of PSI changed during evolution, fundamental functional properties such as trapping efficiency were maintained

A systematic review on health resilience to economic crises

Background The health effects of recent economic crises differ markedly by population group. The objective of this systematic review is to examine evidence from longitudinal studies on factors influencing resilience for any health outcome or health behaviour among the general population living in countries exposed to financial crises. Methods We systematically reviewed studies from six electronic databases (EMBASE, Global Health, MEDLINE, PsycINFO, Scopus, Web of Science) which used quantitative longitudinal study designs and included: (i) exposure to an economic crisis; (ii) changes in health outcomes/behaviours over time; (iii) statistical tests of associations of health risk and/or protective factors with health outcomes/behaviours. The quality of the selected studies was appraised using the Quality Assessment Tool for Quantitative Studies. PRISMA reporting guidelines were followed. Results From 14,584 retrieved records, 22 studies met the eligibility criteria. These studies were conducted across 10 countries in Asia, Europe and North America over the past two decades. Ten socio-demographic factors that increased or protected against health risk were identified: gender, age, education, marital status, household size, employment/occupation, income/ financial constraints, personal beliefs, health status, area of residence, and social relations. These studies addressed physical health, mortality, suicide and suicide attempts, mental health, and health behaviours. Women’s mental health appeared more susceptible to crises than men’s. Lower income levels were associated with greater increases in cardiovascular disease, mortality and worse mental health. Employment status was associated with changes in mental health. Associations with age, marital status, and education were less consistent, although higher education was associated with healthier behaviours. Conclusions Despite widespread rhetoric about the importance of resilience, there was a dearth of studies which operationalised resilience factors. Future conceptual and empirical research is needed to develop the epidemiology of resilience

Thioredoxin 80-Activated-Monocytes (TAMs) Inhibit the Replication of Intracellular Pathogens

BACKGROUND: Thioredoxin 80 (Trx80) is an 80 amino acid natural cleavage product of Trx, produced primarily by monocytes. Trx80 induces differentiation of human monocytes into a novel cell type, named Trx80-activated-monocytes (TAMs). PRINCIPAL FINDINGS: In this investigation we present evidence for a role of TAMs in the control of intracellular bacterial infections. As model pathogens we have chosen Listeria monocytogenes and Brucella abortus which replicate in the cytosol and the endoplasmic reticulum respectively. Our data indicate that TAMs efficiently inhibit intracellular growth of both L. monocytogenes and B. abortus. Further analysis shows that Trx80 activation prevents the escape of GFP-tagged L. monocytogenes into the cytosol, and induces accumulation of the bacteria within the lysosomes. Inhibition of the lysosomal activity by chloroquine treatment resulted in higher replication of bacteria in TAMs compared to that observed in control cells 24 h post-infection, indicating that TAMs kill bacteria by preventing their escape from the endosomal compartments, which progress into a highly degradative phagolysosome. SIGNIFICANCE: Our results show that Trx80 potentiates the bactericidal activities of professional phagocytes, and contributes to the first line of defense against intracellular bacteria

Analysis of the Expression, Secretion and Translocation of the Salmonella enterica Type III Secretion System Effector SteA

Many Gram-negative pathogens possess virulence-related type III secretion systems. Salmonella enterica uses two of these systems, encoded on the pathogenicity islands SPI-1 and SPI-2, respectively, to translocate more than 30 effector proteins into eukaryotic host cells. SteA is one of the few effectors that can be translocated by both systems. We investigated the conditions affecting the synthesis of this effector, its secretion to culture media and its translocation into host cells. Whereas steA was expressed under a wide range of conditions, some factors, including low and high osmolarity, and presence of butyrate, decreased expression. SteA was efficiently secreted to the culture media under both SPI-1 and SPI-2 inducing conditions. The kinetics of translocation into murine macrophages and human epithelial cells was studied using fusions with the 3xFLAG tag, and fusions with CyaA from Bordetella pertussis. Translocation into macrophages under non-invasive conditions was mainly dependent on the SPI-2-encoded type III secretion system but some participation of the SPI-1 system was also detected 6 hours post-infection. Interestingly, both type III secretion systems had a relevant role in the translocation of SteA into epithelial cells. Finally, a deletion approach allowed the identification of the N-terminal signal necessary for translocation of this effector. The amino acid residues 1–10 were sufficient to direct translocation into host cells through both type III secretion systems. Our results provide new examples of functional overlapping between the two type III secretion systems of Salmonella

Measuring the health-related Sustainable Development Goals in 188 countries : a baseline analysis from the Global Burden of Disease Study 2015

Background In September, 2015, the UN General Assembly established the Sustainable Development Goals (SDGs). The SDGs specify 17 universal goals, 169 targets, and 230 indicators leading up to 2030. We provide an analysis of 33 health-related SDG indicators based on the Global Burden of Diseases, Injuries, and Risk Factors Study 2015 (GBD 2015). Methods We applied statistical methods to systematically compiled data to estimate the performance of 33 health-related SDG indicators for 188 countries from 1990 to 2015. We rescaled each indicator on a scale from 0 (worst observed value between 1990 and 2015) to 100 (best observed). Indices representing all 33 health-related SDG indicators (health-related SDG index), health-related SDG indicators included in the Millennium Development Goals (MDG index), and health-related indicators not included in the MDGs (non-MDG index) were computed as the geometric mean of the rescaled indicators by SDG target. We used spline regressions to examine the relations between the Socio-demographic Index (SDI, a summary measure based on average income per person, educational attainment, and total fertility rate) and each of the health-related SDG indicators and indices. Findings In 2015, the median health-related SDG index was 59.3 (95% uncertainty interval 56.8-61.8) and varied widely by country, ranging from 85.5 (84.2-86.5) in Iceland to 20.4 (15.4-24.9) in Central African Republic. SDI was a good predictor of the health-related SDG index (r(2) = 0.88) and the MDG index (r(2) = 0.2), whereas the non-MDG index had a weaker relation with SDI (r(2) = 0.79). Between 2000 and 2015, the health-related SDG index improved by a median of 7.9 (IQR 5.0-10.4), and gains on the MDG index (a median change of 10.0 [6.7-13.1]) exceeded that of the non-MDG index (a median change of 5.5 [2.1-8.9]). Since 2000, pronounced progress occurred for indicators such as met need with modern contraception, under-5 mortality, and neonatal mortality, as well as the indicator for universal health coverage tracer interventions. Moderate improvements were found for indicators such as HIV and tuberculosis incidence, minimal changes for hepatitis B incidence took place, and childhood overweight considerably worsened. Interpretation GBD provides an independent, comparable avenue for monitoring progress towards the health-related SDGs. Our analysis not only highlights the importance of income, education, and fertility as drivers of health improvement but also emphasises that investments in these areas alone will not be sufficient. Although considerable progress on the health-related MDG indicators has been made, these gains will need to be sustained and, in many cases, accelerated to achieve the ambitious SDG targets. The minimal improvement in or worsening of health-related indicators beyond the MDGs highlight the need for additional resources to effectively address the expanded scope of the health-related SDGs.Peer reviewe

EPR spectroscopy as an electronic and structural tool to study photosynthetic cytochrome c550

Resumen del trabajo presentado al 16th Congress of the Spanish Biophysical Society (SBS), celebrado en Sevilla del 6 al 8 de junio de 2017.Cytochrome C550 (Cc550 ) is associated with photosystem II (PSII) in some photosynthetic organisms such as cyanobacteria, diatoms and red algae. The heme group in this protein has the characteristic covalent link to the protein chain and is coordinated to two histidine side chains. Although its function is not determined, a redox role has been proposed based on the redox potential measured when the protein is bound to the PSII. In addition, the redox potential of Cc550 decreases substantially when it is measured in solution in the soluble Cc550 form. The parameters governing this redox potential variation are not known. A change in the electronic levels of iron due to a rearrangement of the axial ligands has been hypothesized. Also, a change in the hydrophobicity of heme environment has been postulated. Here we use Electron Paramagnetic Resonance (EPR) techniques to study two variants of Cc550 from the cyanobacteria Synechocystis sp. and the diatom Phaeodactylum tricornutum to determine the energy distribution of iron electronic levels. Our findings show that variations in relative energy between bound and unbound states and among the different variants are discrete and of comparable magnitude. The comparison of crystal structures, EPR spectra and the sequence rules out the hypothesis of a major rearrangement of axial ligands and rather indicates a different distribution of charges in the heme. The study of nuclear energy levels of iron using 2D pulse EPR techniques of both variants reveals more details about the geometry of the heme site, such as the effect of tilting of one of the axial imidazole rings or its rotation with respect to each other or to the heme molecular frame.Peer Reviewe

Biochemical and biophysical characterization of photosynthetic cytochrome c550 from the diatom Phaeodactylum tricornutum

Resumen del trabajo presentado al IX Meeting of the Protein Structure and Function Network (Reunión Temática de la Red de Estructura y Función de Proteínas), celebrada en Sevilla (España) del 11 al 13 de noviembre de 2015.Cytochrome c550 (Cc550) is a c-type heme protein with a bis-histidinyl axial coordination. It has been described as an extrinsic component of the photosystem II (PSII) membrane complex in cyanobacteria and some eukaryotic algae, although its role within the PSII complex is unknown. Cc550 purified from the diatom Phaeodactylum tricornutum is mostly obtained from the soluble cell extracts, and seems to be truncated in the last two hydrophobic residues of the C-terminal, as deduced from the gene sequence. In addition, Cc550 was absent in purified PSII samples, indicating a low affinity of this protein for the membrane complex. Oxidized Cc550 has been characterized using continuous wave (CW) EPR as well as pulse techniques including ESEEM and HYSCORE. CW measurements reveal a typical low spin heme centre and provide information on the crystal field symmetry related with the axial coordination. ESEEM and HYSCORE experiments show hyperfine coupling of the unpaired spin with nitrogen and hydrogen nuclei in its close vicinity. These interactions are in agreement with the distortion of the heme-axial ligands and loss of the co-planarity of the imidazole ring. The relevant changes in the structure of the single occupied molecular orbital (SOMO) of the heme centre in Cc550 could have implications in their function. Further research is in progress to confirm this point.Peer Reviewe