Structural characterization of the closed conformation of mouse guanylate kinase

Guanylate kinase (GMPK) is a nucleoside monophosphate kinase that catalyzes the reversible phosphoryl transfer from ATP to GMP to yield ADP and GDP. In addition to phosphorylating GMP, antiviral prodrugs such as acyclovir, ganciclovir, and carbovir and anticancer prodrugs such as the thiopurines are dependent on GMPK for their activation. Hence, structural information on mammalian GMPK could play a role in the design of improved antiviral and antineoplastic agents. Here we present the structure of the mouse enzyme in an abortive complex with the nucleotides ADP and GMP, refined at 2.1 Angstrom resolution with a final crystallographic R factor of 0.19 (R-free = 0.23). Guanylate kinase is a member of the nucleoside monophosphate (NMP) kinase family, a family of enzymes that despite having a low primary structure identity share a similar fold, which consists of three structurally distinct regions termed the CORE, LID, and NMP-binding regions. Previous studies on the yeast enzyme have shown that these parts move as rigid bodies upon substrate binding. It has been proposed that consecutive binding of substrates leads to "closing" of the active site bringing the NMP-binding and LID regions closer to each other and to the CORE region. Our structure, which is the first of any guanylate kinase with both substrates bound, supports this hypothesis. It also reveals the binding site of ATP and implicates arginines 44, 137, and 148 (in addition to the invariant P-loop lysine) as candidates for catalyzing the chemical step of the phosphoryl transfer

Analysis of the relationship between tobacco smoking and physical activity in adolescence: a gender specific study

Background and Objective: Although smoking and the physical activity level (PAL) are important determinants of health status in adolescence, there is a lack of information on the relationship between smoking and PAL in early adolescence. The objective of this study was to evaluate the gender-specific relationship between smoking and PAL in 14-to-16-year-old adolescents. Materials and Methods: The sample included 650 adolescents (337 girls, 14.7 ± 0.5 years at first testing wave) from Bosnia and Herzegovina. During the first testing wave, participants were tested using struc-tured questionnaires. Second testing was commenced after approximately 20 months (16.4 ± 0.6 years). The variables were age, gender, socioeconomic status, living environment, cigarette smoking (predictors), and PAL (criterion). Predictors were measured at the first wave, and criterion at the first-wave and second-wave. Results: For girls, smoking was negatively correlated to PAL at the first-wave (OR: 0.75, 95% CI: 0.55–0.95) and at the second-wave (OR: 0.73, 95% CI: 0.71–0.96). No significant association between smoking and PAL was found for boys. Results suggest that adolescent boys and girls do not follow the equal trajectories when it comes to relationships between smoking and PAL. Conclusions: In developing promotional public health actions related to a decrease of smoking and increase of PAL, a gender-specific approach is highly recommended. Further studies analyzing the cause–effect relationship between consumption of other types of psychoactive substances and PAL in this age group are warranted

Levels and changes of physical activity in adolescents during the COVID-19 Pandemic: Contextualizing urban vs. Rural living environment

The COVID-19 pandemic and the social distancing implemented shortly after influence physical activity levels (PALs). The purpose of this investigation was to evaluate the changes in PAL and factors associated with PALs among Croatian adolescents while considering the impact of community (urban vs. rural living environment). The sample included 823 adolescents (mean age: 16.5 ± 2.1 years) who were tested on baseline (from October 2019 to March 2020; before COVID-19 pandemic in Croatia) and follow-up (in April 2020; during the COVID-19 pandemic and imposed rules of social distancing). Baseline testing included anthropometrics, physical fitness status, and evaluation of PALs, while follow-up included only PALs (evaluated by a standardized questionnaire through an internet application). The results showed a significant influence of the living environment on the decrease of PAL, with a larger decrease in urban adolescents. Logistic regression showed a higher likelihood for normal PALs at baseline in adolescents who had better fitness status, with no strong confounding effect of the urban/rural environment. The fitness status of urban adolescents predicted their PALs at follow-up. The differences between urban and rural adolescents with regard to the established changes in PALs and relationships between the predictors and PALs are explained by the characteristics of the living communities (lack of organized sports in rural areas), and the level of social distancing in the studied period and region/country

Structural and electrical properties of Ti doped α-Fe2O3

In this work we have analyzed the effects of Ti doping on structural and electrical properties of α-Fe2O3. When the amount of added Ti (5 wt.%TiO2) was within the solubility degree and XRD, SEM and EDS analysis revealed a homogenous hematite structure, with lattice parameters a= 5.03719(3) Å, c=13.7484(1) Å slightly increased due to incorporation of Ti into the rhombohedral hematite lattice. Higher amounts of Ti (10 wt.%TiO2) resulted in the formation of pseudobrookite, besides hematite, confirmed by SEM and EDS analysis. Studies of electric properties in the temperature range 25-225oC at different frequencies (100 - 1Mz) showed that Ti doping improved electrical conductivity. Impedance analysis was performed using an equivalent circuit, showing one relaxation process and suggesting dominant grain boundary contribution. [Projekat Ministarstva nauke Republike Srbije, br. III45014 i br. III43008

Chromosomes. CENP-C reshapes and stabilizes CENP-A nucleosomes at the centromere

Inheritance of each chromosome depends upon its centromere. A histone H3 variant, centromere protein A (CENP-A), is essential for epigenetically marking centromere location. We find that CENP-A is quantitatively retained at the centromere upon which it is initially assembled. CENP-C binds to CENP-A nucleosomes and is a prime candidate to stabilize centromeric chromatin. Using purified components, we find that CENP-C reshapes the octameric histone core of CENP-A nucleosomes, rigidifies both surface and internal nucleosome structure, and modulates terminal DNA to match the loose wrap that is found on native CENP-A nucleosomes at functional human centromeres. Thus, CENP-C affects nucleosome shape and dynamics in a manner analogous to allosteric regulation of enzymes. CENP-C depletion leads to rapid removal of CENP-A from centromeres, indicating their collaboration in maintaining centromere identity.NIH grants: (GM082989, CA186430, GM008275, GM008216, GM007229); American Heart Association predoctoral fellowship; American Cancer Society postdoctoral fellowship; NSF grant: (agreement DMR-0944772)

Structure of an Enzyme-Derived Phosphoprotein Recognition Domain

Membrane Associated Guanylate Kinases (MAGUKs) contain a protein interaction domain (GKdom) derived from the enzyme Guanylate Kinase (GKenz). Here we show that GKdom from the MAGUK Discs large (Dlg) is a phosphoprotein recognition domain, specifically recognizing the phosphorylated form of the mitotic spindle orientation protein Partner of Inscuteable (Pins). We determined the structure of the Dlg-Pins complex to understand the dramatic transition from nucleotide kinase to phosphoprotein recognition domain. The structure reveals that the region of the GKdom that once served as the GMP binding domain (GBD) has been co-opted for protein interaction. Pins makes significantly more contact with the GBD than does GMP, but primarily with residues that are conserved between enzyme and domain revealing the versatility of the GBD as a platform for nucleotide and protein interactions. Mutational analysis reveals that the GBD is also used to bind the GK ligand MAP1a, suggesting that this is a common mode of MAGUK complex assembly. The GKenz undergoes a dramatic closing reaction upon GMP binding but the protein-bound GKdom remains in the ‘open’ conformation indicating that the dramatic conformational change has been lost in the conversion from nucleotide kinase to phosphoprotein recognition domain

Myalgic encephalomyelitis/chronic fatigue Syndrome (ME/CFS) : Investigating care practices pointed out to disparities in diagnosis and treatment across European Union

ME/CFS is a chronic, complex, multisystem disease that often limits the health and functioning of the affected patients. Diagnosing patients with ME/CFS is a challenge, and many different case definitions exist and are used in clinical practice and research. Even after diagnosis, medical treatment is very challenging. Symptom relief and coping may affect how patients live with their disease and their quality of life. There is no consensus on which diagnostic criteria should be used and which treatment strategies can be recommended for patients. The purpose of the current project was to map the landscape of the Euromene countries in respect of national guidelines and recommendations for case definition, diagnosis and clinical approaches for ME/CFS patients. A 23 items questionnaire was sent out by email to the members of Euromene. The form contained questions on existing guidelines for case definitions, treatment/management of the disease, tests and questionnaires applied, and the prioritization of information for data sampling in research. We obtained information from 17 countries. Five countries reported having national guidelines for diagnosis, and five countries reported having guidelines for clinical approaches. For diagnostic purposes, the Fukuda criteria were most often recommended, and also the Canadian Consensus criteria, the International Consensus Criteria and the Oxford criteria were used. A mix of diagnostic criteria was applied within those countries having no guidelines. Many different questionnaires and tests were used for symptom registration and diagnostic investigation. For symptom relief, pain and anti-depressive medication were most often recommended. Cognitive Behavioral Therapy and Graded Exercise treatment were often recommended as disease management and rehabilitative/palliative strategies. The lack of consistency in recommendations across European countries urges the development of regulations, guidance and standards. The results of this study will contribute to the harmonization of diagnostic criteria and treatment for ME/CFS in Europe