Structural insights into the human RyR2 N-terminal region involved in cardiac arrhythmias

Human ryanodine receptor 2 (hRyR2) mediates calcium release from the sarcoplasmic reticulum, enabling cardiomyocyte contraction. The N-terminal region of hRyR2 (amino acids 1–606) is the target of >30 arrhythmogenic mutations and contains a binding site for phosphoprotein phosphatase 1. Here, the solution and crystal structures determined under near-physiological conditions, as well as a homology model of the hRyR2 N-terminal region, are presented. The N-terminus is held together by a unique network of interactions among its three domains, A, B and C, in which the central helix (amino acids 410–437) plays a prominent stabilizing role. Importantly, the anion-binding site reported for the mouse RyR2 N-terminal region is notably absent from the human RyR2. The structure concurs with the differential stability of arrhythmogenic mutations in the central helix (R420W, I419F and I419F/R420W) which are owing to disparities in the propensity of mutated residues to form energetically favourable or unfavourable contacts. In solution, the N-terminus adopts a globular shape with a prominent tail that is likely to involve residues 545–606, which are unresolved in the crystal structure. Docking the N-terminal domains into cryo-electron microscopy maps of the closed and open RyR1 conformations reveals C atom movements of up to 8 A ° upon channel gating, and predicts the location of the leucine– isoleucine zipper segment and the interaction site for spinophilin and phosphoprotein phosphatase 1 on the RyR surface

Reduced Stability and Increased Dynamics in the Human Proliferating Cell Nuclear Antigen (PCNA) Relative to the Yeast Homolog

Proliferating Cell Nuclear Antigen (PCNA) is an essential factor for DNA replication and repair. PCNA forms a toroidal, ring shaped structure of 90 kDa by the symmetric association of three identical monomers. The ring encircles the DNA and acts as a platform where polymerases and other proteins dock to carry out different DNA metabolic processes. The amino acid sequence of human PCNA is 35% identical to the yeast homolog, and the two proteins have the same 3D crystal structure. In this report, we give evidence that the budding yeast (sc) and human (h) PCNAs have highly similar structures in solution but differ substantially in their stability and dynamics. hPCNA is less resistant to chemical and thermal denaturation and displays lower cooperativity of unfolding as compared to scPCNA. Solvent exchange rates measurements show that the slowest exchanging backbone amides are at the β-sheet, in the structure core, and not at the helices, which line the central channel. However, all the backbone amides of hPCNA exchange fast, becoming undetectable within hours, while the signals from the core amides of scPCNA persist for longer times. The high dynamics of the α-helices, which face the DNA in the PCNA-loaded form, is likely to have functional implications for the sliding of the PCNA ring on the DNA since a large hole with a flexible wall facilitates the establishment of protein-DNA interactions that are transient and easily broken. The increased dynamics of hPCNA relative to scPCNA may allow it to acquire multiple induced conformations upon binding to its substrates enlarging its binding diversity

Quality of Life in Patients with Diabetic Foot Ulcer in the Visegrad Countries

AIM AND OBJECTIVES: The aim of the present study was to identify the quality of life of patients with diabetic foot ulcers in the Visegrad countries. BACKGROUND: The diabetics with foot ulcers are principally evaluated on the basis of physical parameters, but this does not always reveal much about the patient's experience of life with ulceration. DESIGN: The cross-sectional study. METHODS: The standardized generic questionnaire World Health Organisation Quality of Life Bref was used. The sample was made up of 525 participants and the calculations were performed using the IBM SPSS statistical program. RESULTS: The significant negative correlations between demographic data such as age, duration of diabetes mellitus, duration of diabetes ulceration treatment and a lower level of quality of life were found across the sample. The statistically significant differences according to clinical characteristics such as Wagner classification, frequency of foot ulcers, present peripheral vascular diseas and pain in terms of quality of life were also revealed. Significant differences of quality of life among Visegrad countries were revealed: Hungary's participants had a worse quality of life than others, while Slovak participants expressed lower satisfaction with their health than Czech. CONCLUSIONS: Socio-demographic factors and clinical characteristics influence the quality of life of patients with diabetic foot ulcer. Significant differences between patients of Visegrad countries were found in all domains of quality of life: physical, psychological, social and environmental. RELEVANCE TO CLINICAL PRACTICE: The quality of life of patients with diabetic foot ulcer reflects the conditions and health care system in each of the Visegrad countries. We have to respect socio-demographic factors and clinical characteristics in nursing care. This could have an impact on managing patient care not only with regard to their diabetic foot ulcer but also with regard to the patient as a personality with their own problems in relation to physical, psychosocial and environmental conditions. This article is protected by copyright. All rights reserved

Structural insights into the human RyR2 N terminal region involved in cardiac arrhythmias

Human ryanodine receptor 2 hRyR2 mediates calcium release from the sarcoplasmic reticulum, enabling cardio myocyte contraction. The N terminal region of hRyR2 amino acids 1 606 is the target of gt;30 arrhythmogenic mutations and contains a binding site for phosphoprotein phosphatase 1. Here, the solution and crystal structures determined under near physiological conditions, as well as a homology model of the hRyR2 N terminal region, are presented. The N terminus is held together by a unique network of interactions among its three domains, A, B and C, in which the central helix amino acids 410 437 plays a prominent stabilizing role. Importantly, the anion binding site reported for the mouse RyR2 N terminal region is notably absent from the human RyR2. The structure concurs with the differential stability of arrhythmogenic mutations in the central helix R420W, I419F and I419F R420W which are owing to disparities in the propensity of mutated residues to form energetically favourable or unfavourable contacts. In solution, the N terminus adopts a globular shape with a prominent tail that is likely to involve residues 545 606, which are unresolved in the crystal structure. Docking the N terminal domains into cryo electron microscopy maps of the closed and open RyR1 conformations reveals C[alpha] atom movements of up to 8 upon channel gating, and predicts the location of the leucine isoleucine zipper segment and the interaction site for spinophilin and phosphoprotein phosphatase 1 on the RyR surfac

Simultaneous Removal of Metal Ions from Wastewater by a Greener Approach

The examination of the performance of raw and immobilized S. (Saccharomyces) cerevisiae in the simultaneous abatement of metal ions from wastewater effluent is the focal point of this article. The optimal storage time for raw and immobilized S. cerevisiae, during which they can be utilized, was estimated. The outcomes revealed that as the initial metal ion concentrations increased, the adsorption capacity improved, while the removal efficiency of S. cerevisiae yeast cells decreased, with the highest uptake obtained at the optimal conditions: pH = 5.0, 2.0 g S. cerevisiae/L, 25 °C, and a contact time of 25 min. The maximum adsorption capacities (qmax) for Pb(II), Cd(II), and Ni(II) ions are shown by Langmuir at 65, 90, and 51 mg/g, respectively. It was discovered that the metal ions’ biosorption reactions were spontaneous and were fitted by the pseudo-second-order model. The mechanisms of the metal ions’ abatement were explained by using XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), (BET) Brunauer–Emmett–Teller, and TEM (transmission electron microscopy) outputs. EDTA and citric acid can eliminate more than 70 ± 4 and 90 ± 5% of the adsorbed ions, respectively. The experiment of storage demonstrated that the immobilized S. cerevisiae was more stable for 8 months than the raw yeast

The Structural Basis for mRNA Recognition and Cleavage by the Ribosome-Dependent Endonuclease RelE

Translational control is widely used to adjust gene expression levels. During the stringent response in bacteria, mRNA is degraded on the ribosome by the ribosome-dependent endonuclease, RelE. The molecular basis for recognition of the ribosome and mRNA by RelE and the mechanism of cleavage are unknown. Here, we present crystal structures of E. coli RelE in isolation (2.5 Å) and bound to programmed Thermus thermophilus 70S ribosomes before (3.3 Å) and after (3.6 Å) cleavage. RelE occupies the A site and causes cleavage of mRNA after the second nucleotide of the codon by reorienting and activating the mRNA for 2′-OH-induced hydrolysis. Stacking of A site codon bases with conserved residues in RelE and 16S rRNA explains the requirement for the ribosome in catalysis and the subtle sequence specificity of the reaction. These structures provide detailed insight into the translational regulation on the bacterial ribosome by mRNA cleavage