Catalytic Mechanism of Mycobacterium tuberculosis Methionine Sulfoxide Reductase A.

The oxidation of Met to methionine sulfoxide (MetSO) by oxidants such as hydrogen peroxide, hypochlorite, or peroxynitrite has profound effects on protein function. This modification can be reversed by methionine sulfoxide reductases (msr). In the context of pathogen infection, the reduction of oxidized proteins gains significance due to microbial oxidative damage generated by the immune system. For example, Mycobacterium tuberculosis (Mt) utilizes msrs (MtmsrA and MtmsrB) as part of the repair response to the host-induced oxidative stress. The absence of these enzymes makes Mycobacteria prone to increased susceptibility to cell death, pointing them out as potential therapeutic targets. This study provides a detailed characterization of the catalytic mechanism of MtmsrA using a comprehensive approach, including experimental techniques and theoretical methodologies. Confirming a ping-pong type enzymatic mechanism, we elucidate the catalytic parameters for sulfoxide and thioredoxin substrates (kcat/KM = 2656 ± 525 M-1 s-1 and 1.7 ± 0.8 × 106 M-1 s-1, respectively). Notably, the entropic nature of the activation process thermodynamics, representing ∼85% of the activation free energy at room temperature, is underscored. Furthermore, the current study questions the plausibility of a sulfurane intermediate, which may be a transition-state-like structure, suggesting the involvement of a conserved histidine residue as an acid-base catalyst in the MetSO reduction mechanism. This mechanistic insight not only advances our understanding of Mt antioxidant enzymes but also holds implications for future drug discovery and biotechnological applications.

Bacterial toxins and heart function: heat-labile Escherichia coli enterotoxin B promotes changes in cardiac function with possible relevance for sudden cardiac death.

Bacterial toxins can cause cardiomyopathy, though it is not its most common cause. Some bacterial toxins can form pores in the membrane of cardiomyocytes, while others can bind to membrane receptors. Enterotoxigenic E. coli can secrete enterotoxins, including heat-resistant (ST) or labile (LT) enterotoxins. LT is an AB5-type toxin that can bind to specific cell receptors and disrupt essential host functions, causing several common conditions, such as certain diarrhea. The pentameric B subunit of LT, without A subunit (LTB), binds specifically to certain plasma membrane ganglioside receptors, found in lipid rafts of cardiomyocytes. Isolated guinea pig hearts and cardiomyocytes were exposed to different concentrations of purified LTB. In isolated hearts, mechanical and electrical alternans and an increment of heart rate variability, with an IC50 of ~0.2 µg/ml LTB, were observed. In isolated cardiomyocytes, LTB promoted significant decreases in the amplitude and the duration of action potentials. Na+ currents were inhibited whereas L-type Ca2+ currents were augmented at their peak and their fast inactivation was promoted. Delayed rectifier K+ currents decreased. Measurements of basal Ca2+ or Ca2+ release events in cells exposed to LTB suggest that LTB impairs Ca2+ homeostasis. Impaired calcium homeostasis is linked to sudden cardiac death. The results are consistent with the recent view that the B subunit is not merely a carrier of the A subunit, having a role explaining sudden cardiac death in children (SIDS) infected with enterotoxigenic E. coli, explaining several epidemiological findings that establish a strong relationship between SIDS and ETEC E. coli. Supplementary Information: The online version contains supplementary material available at 10.1007/s12551-023-01100-6.

Nutrigenomics of inward rectifier potassium channels.

Inwardly rectifying potassium (Kir) channels play a key role in maintaining the resting membrane potential and supporting potassium homeostasis. There are many variants of Kir channels, which are usually tetramers in which the main subunit has two trans-membrane helices attached to two N- and C-terminal cytoplasmic tails with a pore-forming loop in between that contains the selectivity filter. These channels have domains that are strongly modulated by molecules present in nutrients found in different diets, such as phosphoinositols, polyamines and Mg2+. These molecules can impact these channels directly or indirectly, either allosterically by modulation of enzymes or via the regulation of channel expression. A particular type of these channels is coupled to cell metabolism and inhibited by ATP (KATP channels, essential for insulin release and for the pathogenesis of metabolic diseases like diabetes mellitus). Genomic changes in Kir channels have a significant impact on metabolism, such as conditioning the nutrients and electrolytes that an individual can take. Thus, the nutrigenomics of ion channels is an important emerging field in which we are attempting to understand how nutrients and diets can affect the activity and expression of ion channels and how genomic changes in such channels may be the basis for pathological conditions that limit nutrition and electrolyte intake. In this contribution we briefly review Kir channels, discuss their nutrigenomics, characterize how different components in the diet affect their function and expression, and suggest how their genomic changes lead to pathological phenotypes that affect diet and electrolyte intake.

Redox sensitive human mitochondrial aconitase and its interaction with frataxin: In vitro and in silico studies confirm that it takes two to tango.

Mitochondrial aconitase (ACO2) has been postulated as a redox sensor in the tricarboxylic acid cycle. Its high sensitivity towards reactive oxygen and nitrogen species is due to its particularly labile [4Fe-4S]2+ prosthetic group which yields an inactive [3Fe-4S]+ cluster upon oxidation. Moreover, ACO2 was found as a main oxidant target during aging and in pathologies where mitochondrial dysfunction is implied. Herein, we report the expression and characterization of recombinant human ACO2 and its interaction with frataxin (FXN), a protein that participates in the de novo biosynthesis of Fe-S clusters. A high yield of pure ACO2 (≥99%, 22 ± 2 U/mg) was obtained and kinetic parameters for citrate, isocitrate, and cis-aconitate were determined. Superoxide, carbonate radical, peroxynitrite, and hydrogen peroxide reacted with ACO2 with second-order rate constants of 108, 108, 105, and 102 M-1 s-1, respectively. Temperature-induced unfolding assessed by tryptophan fluorescence of ACO2 resulted in apparent melting temperatures of 51.1 ± 0.5 and 43.6 ± 0.2 °C for [4Fe-4S]2+ and [3Fe-4S]+ states of ACO2, sustaining lower thermal stability upon cluster oxidation. Differences in protein dynamics produced by the Fe-S cluster redox state were addressed by molecular dynamics simulations. Reactivation of [3Fe-4S]+-ACO2 by FXN was verified by activation assays and direct iron-dependent interaction was confirmed by protein-protein interaction ELISA and fluorescence spectroscopic assays. Multimer modeling and protein-protein docking predicted an ACO2-FXN complex where the metal ion binding region of FXN approaches the [3Fe-4S]+ cluster, supporting that FXN is a partner for reactivation of ACO2 upon oxidative cluster inactivation.

Thiol-based chemical probes exhibit antiviral activity against SARS-CoV-2 via allosteric disulfide disruption in the spike glycoprotein.

The development of small-molecules targeting different components of SARS-CoV-2 is a key strategy to complement antibody-based treatments and vaccination campaigns in managing the COVID-19 pandemic. Here, we show that two thiol-based chemical probes that act as reducing agents, P2119 and P2165, inhibit infection by human coronaviruses, including SARS-CoV-2, and decrease the binding of spike glycoprotein to its receptor, the angiotensin-converting enzyme 2 (ACE2). Proteomics and reactive cysteine profiling link the antiviral activity to the reduction of key disulfides, specifically by disruption of the Cys379-Cys432 and Cys391-Cys525 pairs distal to the receptor binding motif in the receptor binding domain (RBD) of the spike glycoprotein. Computational analyses provide insight into conformation changes that occur when these disulfides break or form, consistent with an allosteric role, and indicate that P2119/P2165 target a conserved hydrophobic binding pocket in the RBD with the benzyl thiol-reducing moiety pointed directly toward Cys432. These collective findings establish the vulnerability of human coronaviruses to thiol-based chemical probes and lay the groundwork for developing compounds of this class, as a strategy to inhibit the SARS-CoV-2 infection by shifting the spike glycoprotein redox scaffold.

Character Strengths Predict Subjective Well-Being, Psychological Well-Being, and Psychopathological Symptoms, Over and Above Functional Social Support.

The increasing value of character strengths in the prediction of well-being and psychopathology, after the effects of functional social support and sociodemographic variables are accounted for, is examined. Participants were 1494 Spanish-speaking students between the ages of 18 and 68 (43.3% men and 56.7% women) who completed measures of character strengths, functional social support, subjective well-being, psychological well-being, and symptoms of psychopathology. Functional social support had predictive value in explaining the variability of each component of well-being and psychopathology. Regarding character strengths, theological strengths had the greatest predictive power for life satisfaction (ß = 0.41), positive affect (ß = 0.49), affect balance (ß = 0.45), purpose in life (ß = 0.60), self-acceptance (ß = 0.50), environmental mastery (ß = 0.47), and positive relations with others (ß = 0.25). Emotional strengths made the strongest contribution to the variance explained (ß = 0.41) of autonomy, and intellectual strengths were the strongest predictive variable for personal growth (ß = 0.39). Strengths of restraint had the greatest predictive power for the global severity index of psychopathology (ß = -0.27). Functional social support and character strengths have strong links to mental health. Positive interventions to develop these variables could contribute to enhance well-being and prevent psychological distress.

Application of S-1 Bifactor Model to Evaluate the Structural Validity of TMMS-24.

(1) Background: Recent studies have shown that the internal structure of TMMS-24 can be conceptualized as a bifactor. However, these studies, based exclusively on the evaluation of the fit of the model, fail to show the existence of a general factor of strong emotional intelligence and have neglected the evaluation of the specific factors of attention, clarity and repair. The main goal of this work is to evaluate the degree of determination and reliability of the specific factors of TMMS-24 using a bifactor S-1 model. (2) Methods: We administered TMMS-24 to a sample of 384 students from middle and high schools (58.1% girls; mean age = 15.5; SD = 1.8). (3) Results: The specific TMMS-24 factors are better determined and present a higher internal consistency than the general factor. Furthermore, the bifactor S-1 model shows the existence of a hierarchical relationship between the attention factor and the clarity and repair factors. The S-1 bifactor model is the only one that was shown to be invariant as a function of the sex of the participants. (4) Conclusions: The S-1 bifactor model has proven to be a promising tool for capturing the structural complexity of TMMS-24. Its application indicates that it is not advisable to use the sum score of the items, since it would be contaminated by the attention factor. In addition, this score would not be invariant either, that is, comparisons by sex would be invalid.

Cardiolipin interactions with cytochrome c increase tyrosine nitration yields and site-specificity.

The interaction between cytochrome c and cardiolipin is a relevant process in the mitochondrial redox homeostasis, playing roles in the mechanism of electron transfer to cytochrome c oxidase and also modulating cytochrome c conformation, reactivity and function. Peroxynitrite is a widespread nitrating agent formed in mitochondria under oxidative stress conditions, and can result in the formation of tyrosine nitrated cytochrome c. Some of the nitro-cytochrome c species undergo conformational changes at physiological pH and increase its peroxidase activity. In this work we evaluated the influence of cardiolipin on peroxynitrite-mediated cytochrome c nitration yields and site-specificity. Our results show that cardiolipin enhances cytochrome c nitration by peroxynitrite and targets it to heme-adjacent Tyr67. Cytochrome c nitration also modifies the affinity of protein with cardiolipin. Using a combination of experimental techniques and computer modeling, it is concluded that structural modifications in the Tyr67 region are responsible for the observed changes in protein-derived radical and tyrosine nitration levels, distribution of nitrated proteoforms and affinity to cardiolipin. Increased nitration of cytochrome c in presence of cardiolipin within mitochondria and the gain of peroxidatic activity could then impact events such as the onset of apoptosis and other processes related to the disruption of mitochondrial redox homeostasis.

Emotional Intelligence and the Different Manifestations of Bullying in Children.

The main objective of this research was to help clarify the relationship between ability emotional intelligence (AEI) and bullying in children. Bullying is a maladaptive behaviour that generates severe adverse consequences in the school environment and is a matter of growing concern in the educational community. To investigate the relationship between AEI and bullying, we administered two tests to a sample of 329 students (52.9% girls) aged between 8 and 12 years old (Mage = 9.3; SD = 1.2). AEI was assessed using a test based on the interpretation of cinema scenes (EMOCINE). EMOCINE was designed to measure two of the primary factors considered in Mayer and Salovey's ability model: emotional perception and emotional understanding. Furthermore, we administered a measure of bullying and school violence (AVE), which provides a global index of bullying, as well as a measure of its intensity, by considering eight scales or types of victimisation (harassment, intimidation, coercion, threats, social blocking, social exclusion, manipulation and aggression). The results show that age had a statistically significant effect on measures of bullying, while gender showed an interaction with victimisation types. A reduction in bullying behaviours was observed as the age of children increased, while gender-based analyses revealed different patterns in bullying behaviours. Regarding EI, it was observed that students with high AEI scores presented the lowest levels in both global bullying indexes and the victimisation types. Consequently, AEI seems to have important implications for bullying behaviours, and therefore, interventions aimed at the evaluation, training and development of AEI might offer the educational community the possibility of preventing or redirecting bullying situations.

Social Intelligence and Psychological Distress: Subjective and Psychological Well-Being as Mediators.

The strength named "social intelligence" in the Values in Action (VIA) Classification of Character Strengths and Virtues represents emotional, personal, and social intelligences, which are considered "hot intelligences". This work contributed to the study of the mechanisms of influence of social intelligence on mental health. A multiple mediation model was proposed to quantify the direct effect of social intelligence on psychopathological symptoms, as well as its indirect effect through its impact on components of subjective and psychological well-being. This study involved 1407 university students who completed the Values in Action Inventory of Strengths (VIA-IS), the Satisfaction with Life Scale (SWLS), the Positive and Negative Affect Schedule (PANAS), the Psychological Well-Being Scales (PWBS), and the Symptom Checklist-90-Revised (SCL-90-R). Social intelligence was found to be significantly associated with life satisfaction (a = 0.33, p < 0.001), positive affect (a = 0.42, p < 0.001), and negative affect (a = -0.21, p < 0.001), transmitting significant indirect effects on psychopathological symptomatology through these components of subjective well-being. Likewise, social intelligence was positively and significantly related to psychological well-being (a-paths ranged from 0.31 to 0.43, p < 0.001), exerting significant and negative indirect effects on psychological distress through the dimension of positive relations with other people. These results could be useful in order to expand the explanatory models of the influence of social intelligence on mental health and to design interventions based on this strength for the promotion of well-being and the reduction in psychological distress.

Corrigendum: Emotional Intelligence in Elementary School Children. EMOCINE, a Novel Assessment Test Based on the Interpretation of Cinema Scenes.

[This corrects the article DOI: 10.3389/fpsyg.2019.01882.].

Emotional Intelligence in Elementary School Children. EMOCINE, a Novel Assessment Test Based on the Interpretation of Cinema Scenes.

The aim of the present study was to validate a new procedure, called EMOCINE test, to measure the perception and understanding branches of emotional intelligence (EI) in 1,448 children, aged between 8 and 13 years, from elementary schools. This new tool consists of watching 15 cartoon film clips and interpreting them according to children's own emotional perception and comprehension. After completing the test, the participants were classifie, according to their responses and by using the latent class analysis, as naïve (16.1%), over-interpretative (33.5%), and sensitive (50.4%). An increase in sensitive responses was observed depending on participants sex (girls higher than boys), and academic grade (increasing over the grades). Participants from the sensitive latent class had a significant better behavior in the school/classroom, compared with those from naïve and over-interpretative groups. Likewise, significant differences between latent classes were observed in many psychological, emotional, and behavioral problems (mainly between sensitive vs. insensitive by naivety) such as: depression, post-traumatic symptomatology, attention problems, aggression, family problems, problems at school, problems with classmates, integration and social competence. In conclusion, EMOCINE is a novel and promising tool for the measurement of the perception and comprehension components of EI. The test, employing film clips, is more realistic and motivating than others using static images or written descriptions. Moreover, the test can predict or identify emotional and behavior problems in children.