Functional domains of a ribosome arresting peptide are affected by surrounding nonconserved residues.

Expression of the Escherichia coli tnaCAB operon, responsible for L-tryptophan (L-Trp) transport and catabolism, is regulated by L-Trp-directed translation arrest and the ribosome arresting peptide TnaC. The function of TnaC relies on conserved residues distributed throughout the peptide, which are involved in forming an L-Trp binding site at the ribosome exit tunnel and inhibiting the ribosome function. We aimed to understand whether nonconserved amino acids surrounding these critical conserved residues play a functional role in TnaC-mediated ribosome arrest. We have isolated two intragenic suppressor mutations that restore arrest function of TnaC mutants; one of these mutations is located near the L-Trp binding site, while the other mutation is located near the ribosome active site. We used reporter gene fusions to show that both suppressor mutations have similar effects on TnaC mutants at the conserved residues involved in forming a free L-Trp binding site. However, they diverge in suppressing loss-of-function mutations in a conserved TnaC residue at the ribosome active site. With ribosome toeprinting assays, we determined that both suppressor mutations generate TnaC peptides, which are highly sensitive to L-Trp. Puromycin-challenge assays with isolated arrested ribosomes indicate that both TnaC suppressor mutants are resistant to peptidyl-tRNA cleavage by puromycin in the presence of L-Trp; however, they differ in their resistance to puromycin in the absence of L-Trp. We propose that the TnaC peptide two functionally distinct segments, a sensor domain and a stalling domain, and that the functional versatility of these domains is fine-tuned by the nature of their surrounding nonconserved residues.

Generating New Musical Preferences From Multilevel Mapping of Predictions to Reward.

Much of what we know and love about music hinges on our ability to make successful predictions, which appears to be an intrinsically rewarding process. Yet the exact process by which learned predictions become pleasurable is unclear. Here we created novel melodies in an alternative scale different from any established musical culture to show how musical preference is generated de novo. Across nine studies (n = 1,185), adult participants learned to like more frequently presented items that adhered to this rapidly learned structure, suggesting that exposure and prediction errors both affected self-report liking ratings. Learning trajectories varied by music-reward sensitivity but were similar for U.S. and Chinese participants. Furthermore, functional MRI activity in auditory areas reflected prediction errors, whereas functional connectivity between auditory and medial prefrontal regions reflected both exposure and prediction errors. Collectively, results support predictive coding as a cognitive mechanism by which new musical sounds become rewarding.

Dynamic emotional states shape the episodic structure of memory.

Human emotions fluctuate over time. However, it is unclear how these shifting emotional states influence the organization of episodic memory. Here, we examine how emotion dynamics transform experiences into memorable events. Using custom musical pieces and a dynamic emotion-tracking tool to elicit and measure temporal fluctuations in felt valence and arousal, our results demonstrate that memory is organized around emotional states. While listening to music, fluctuations between different emotional valences bias temporal encoding process toward memory integration or separation. Whereas a large absolute or negative shift in valence helps segment memories into episodes, a positive emotional shift binds sequential representations together. Both discrete and dynamic shifts in music-evoked valence and arousal also enhance delayed item and temporal source memory for concurrent neutral items, signaling the beginning of new emotional events. These findings are in line with the idea that the rise and fall of emotions can sculpt unfolding experiences into memories of meaningful events.

The Antidepressant Sertraline Affects Cell Signaling and Metabolism in Trichophyton rubrum.

The dermatophyte Trichophyton rubrum is responsible for most human cutaneous infections. Its treatment is complex, mainly because there are only a few structural classes of fungal inhibitors. Therefore, new strategies addressing these problems are essential. The development of new drugs is time-consuming and expensive. The repositioning of drugs already used in medical practice has emerged as an alternative to discovering new drugs. The antidepressant sertraline (SRT) kills several important fungal pathogens. Accordingly, we investigated the inhibitory mechanism of SRT in T. rubrum to broaden the knowledge of its impact on eukaryotic microorganisms and to assess its potential for future use in dermatophytosis treatments. We performed next-generation sequencing (RNA-seq) to identify the genes responding to SRT at the transcript level. We identified that a major effect of SRT was to alter expression for genes involved in maintaining fungal cell wall and plasma membrane stability, including ergosterol biosynthetic genes. SRT also altered the expression of genes encoding enzymes related to fungal energy metabolism, cellular detoxification, and defense against oxidative stress. Our findings provide insights into a specific molecular network interaction that maintains metabolic stability and is perturbed by SRT, showing potential targets for its strategic use in dermatophytosis.

Variation in bittersweet nostalgic feelings and their divergent effects on daily well-being.

Experimental manipulations of nostalgia that privilege positive aspects of the bittersweet emotion have led to the conclusion that nostalgia is a predominantly positive emotion, yet nostalgia covaries negatively with well-being in daily life. To reconcile this discrepancy, we developed and tested the bittersweet variation model of nostalgia that posits that (a) nostalgic feelings vary not only in intensity but also in valence (i.e., how bitter or sweet a nostalgic feeling is); (b) daily events influence the valence of nostalgic feelings; and (c) nostalgia's valence influences well-being. Across two daily diary studies (N = 151; 1,356 daily reports), we found that the valence of nostalgic feelings varied considerably within-persons. Daily positive events predicted more positively rated nostalgic feelings, whereas daily negative events predicted more negatively rated nostalgic feelings. Controlling for the effects of daily events on well-being, positive nostalgic feelings predicted greater well-being, whereas negative nostalgic feelings predicted lower well-being. To provide more robust causal evidence of the effect of nostalgia valence on well-being, we conducted two experiments (N = 445) in which we manipulated nostalgia valence by asking participants to write about positive nostalgic feelings (involving people they remain close to) or negative nostalgia feelings (involving people they no longer remain close to), mimicking typical nostalgic feelings in daily life. Positive nostalgic feelings improved well-being compared with negative nostalgic feelings. Thus, nostalgia is not inherently positive or negative. Rather, the effect of nostalgia on well-being depends on its valence, which is influenced by the eliciting event. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A circadian clock translational control mechanism targets specific mRNAs to cytoplasmic messenger ribonucleoprotein granules.

Phosphorylation of Neurospora crassa eukaryotic initiation factor 2 α (eIF2α), a conserved translation initiation factor, is clock controlled. To determine the impact of rhythmic eIF2α phosphorylation on translation, we performed temporal ribosome profiling and RNA sequencing (RNA-seq) in wild-type (WT), clock mutant Δfrq, eIF2α kinase mutant Δcpc-3, and constitutively active cpc-3c cells. About 14% of mRNAs are rhythmically translated in WT cells, and translation rhythms for ∼30% of these mRNAs, which we named circadian translation-initiation-controlled genes (cTICs), are dependent on the clock and CPC-3. Most cTICs are expressed from arrhythmic mRNAs and contain a P-body (PB) localization motif in their 5' leader sequence. Deletion of SNR-1, a component of cytoplasmic messenger ribonucleoprotein granules (cmRNPgs) that include PBs and stress granules (SGs), and the PB motif on one of the cTIC mRNAs, zip-1, significantly alters zip-1 rhythmic translation. These results reveal that the clock regulates rhythmic translation of specific mRNAs through rhythmic eIF2α activity and cmRNPg metabolism.

Corrigendum: The negative interactive effects of nostalgia and loneliness on affect in daily life.

[This corrects the article DOI: 10.3389/fpsyg.2020.02185.].

The Antidepressant Sertraline Induces the Formation of Supersized Lipid Droplets in the Human Pathogen Cryptococcus neoformans.

The prevalence and increasing incidence of fungal infections globally is a significant worldwide health problem. Cryptococcosis, primarily caused by the pathogenic yeast Cryptococcus neoformans, is responsible for approximately 181,000 estimated deaths annually. The scarcity of treatments and the increasing resistance to current therapeutics highlight the need for the development of antifungal agents which have novel mechanisms of action and are suitable for clinical use. Repurposing existing FDA-approved compounds as antimycotic therapeutics is a promising strategy for the rapid development of such new treatments. Sertraline (SRT), a commonly prescribed antidepressant, is a broad-spectrum antifungal agent with particular efficacy against C. neoformans. However, the effect of SRT on fungal physiology is not understood. Here, we report that SRT induces the formation of supersized lipid droplets (SLDs) in C. neoformans, and in Candida albicans, Saccharomyces cerevisiae, and Aspergillus fumigatus. SLDs were not induced in C. neoformans by treatment with the antifungal fluconazole (FLC), consistent with SRT and FLC acting differently to perturb C. neoformans physiology. The formation of SLDs in response to SRT indicates that this compound alters the lipid metabolism of C. neoformans. Moreover, the SRT-induced enlargement of LDs in other fungal species may indicate a common fungal response to SRT.

E-site drug specificity of the human pathogen Candida albicans ribosome.

Candida albicans is a widespread commensal fungus with substantial pathogenic potential and steadily increasing resistance to current antifungal drugs. It is known to be resistant to cycloheximide (CHX) that binds to the E-transfer RNA binding site of the ribosome. Because of lack of structural information, it is neither possible to understand the nature of the resistance nor to develop novel inhibitors. To overcome this issue, we determined the structure of the vacant C. albicans 80S ribosome at 2.3 angstroms and its complexes with bound inhibitors at resolutions better than 2.9 angstroms using cryo-electron microscopy. Our structures reveal how a change in a conserved amino acid in ribosomal protein eL42 explains CHX resistance in C. albicans and forms a basis for further antifungal drug development.

Structure of the translating Neurospora ribosome arrested by cycloheximide.

Ribosomes translate RNA into proteins. The protein synthesis inhibitor cycloheximide (CHX) is widely used to inhibit eukaryotic ribosomes engaged in translation elongation. However, the lack of structural data for actively translating polyribosomes stalled by CHX leaves unanswered the question of which elongation step is inhibited. We elucidated CHX's mechanism of action based on the cryo-electron microscopy structure of actively translating Neurospora crassa ribosomes bound with CHX at 2.7-Å resolution. The ribosome structure from this filamentous fungus contains clearly resolved ribosomal protein eL28, like higher eukaryotes but unlike budding yeast, which lacks eL28. Despite some differences in overall structures, the ribosomes from Neurospora, yeast, and humans all contain a highly conserved CHX binding site. We also sequenced classic Neurospora CHX-resistant alleles. These mutations, including one at a residue not previously observed to affect CHX resistance in eukaryotes, were in the large subunit proteins uL15 and eL42 that are part of the CHX-binding pocket. In addition to A-site transfer RNA (tRNA), P-site tRNA, messenger RNA, and CHX that are associated with the translating N. crassa ribosome, spermidine is present near the CHX binding site close to the E site on the large subunit. The tRNAs in the peptidyl transferase center are in the A/A site and the P/P site. The nascent peptide is attached to the A-site tRNA and not to the P-site tRNA. The structural and functional data obtained show that CHX arrests the ribosome in the classical PRE translocation state and does not interfere with A-site reactivity.

Music and mood regulation during the early stages of the COVID-19 pandemic.

Music listening can be an effective strategy for regulating affect, leading to positive well-being. However, it is unclear how differences in disposition and personality can impact music's affective benefits in response to acute and major real-world stressful events. The COVID-19 pandemic provides a unique opportunity to study how music is used to cope with stress, loss, and unease across the world. During the first month of the spread of the COVID pandemic, we used an online survey to test if people from four different countries used music to manage their emotions during quarantine and if the functions of music depended on empathy, anxiety, depression, or country of residence. We found a positive relationship between the use of music listening for affect regulation and current well-being, particularly for participants from India. While people with stronger symptoms of depression and anxiety used music differently, the end result was still a positive change in affect. Our findings highlight the universality of music's affective potency and its ability to help people manage an unprecedented life stressor.

Structural basis for the tryptophan sensitivity of TnaC-mediated ribosome stalling.

Free L-tryptophan (L-Trp) stalls ribosomes engaged in the synthesis of TnaC, a leader peptide controlling the expression of the Escherichia coli tryptophanase operon. Despite extensive characterization, the molecular mechanism underlying the recognition and response to L-Trp by the TnaC-ribosome complex remains unknown. Here, we use a combined biochemical and structural approach to characterize a TnaC variant (R23F) with greatly enhanced sensitivity for L-Trp. We show that the TnaC-ribosome complex captures a single L-Trp molecule to undergo termination arrest and that nascent TnaC prevents the catalytic GGQ loop of release factor 2 from adopting an active conformation at the peptidyl transferase center. Importantly, the L-Trp binding site is not altered by the R23F mutation, suggesting that the relative rates of L-Trp binding and peptidyl-tRNA cleavage determine the tryptophan sensitivity of each variant. Thus, our study reveals a strategy whereby a nascent peptide assists the ribosome in detecting a small metabolite.

Clarifying the link between music and social bonding by measuring prosociality in context.

To corroborate the music and social bonding hypothesis, we propose that future investigations isolate specific components of social bonding and consider the influence of context. We deconstruct and operationalize social bonding through the lens of social psychology and provide examples of specific measures that can be used to assess how the link between music and sociality varies by context.

Conserved Upstream Open Reading Frame Nascent Peptides That Control Translation.

Cells utilize transcriptional and posttranscriptional mechanisms to alter gene expression in response to environmental cues. Gene-specific controls, including changing the translation of specific messenger RNAs (mRNAs), provide a rapid means to respond precisely to different conditions. Upstream open reading frames (uORFs) are known to control the translation of mRNAs. Recent studies in bacteria and eukaryotes have revealed the functions of evolutionarily conserved uORF-encoded peptides. Some of these uORF-encoded nascent peptides enable responses to specific metabolites to modulate the translation of their mRNAs by stalling ribosomes and through ribosome stalling may also modulate the level of their mRNAs. In this review, we highlight several examples of conserved uORF nascent peptides that stall ribosomes to regulate gene expression in response to specific metabolites in bacteria, fungi, mammals, and plants.

The Negative Interactive Effects of Nostalgia and Loneliness on Affect in Daily Life.

Research has suggested that nostalgia is a mixed, albeit predominantly positive emotion. One proposed function of nostalgia is to attenuate the negative consequences of loneliness. This restorative effect of nostalgia, however, has been demonstrated with cross sectional and experimental methods that lack ecological validity. In studies that have measured nostalgia in daily life, however, nostalgia has been negatively related to well-being. We propose an alternative theory that posits that the effect of nostalgia on well-being depends on the event or experience that elicits nostalgia. We tested this theory by measuring daily states of nostalgia, loneliness, and affect across five daily diary studies (N = 504; 6,004 daily reports) that lasted for 14 days. Using multilevel modeling, we found that nostalgia and loneliness were negatively related to positive affect and positively related to negative affect. The negative effects of nostalgia on affective well-being were significantly stronger on days when people felt more lonely as opposed to less lonely. Viewed alternatively, the negative effects of loneliness on affective well-being were stronger on days when people felt more vs. less nostalgic. Thus, in contrast to experimental findings, nostalgia did not attenuate, but rather exaggerated the negative effects of loneliness on affective well-being. These findings support a theoretical account that proposes that the effect of nostalgia on well-being depends on the natural context in which nostalgia is elicited.

Circadian clock control of eIF2α phosphorylation is necessary for rhythmic translation initiation.

The circadian clock in eukaryotes controls transcriptional and posttranscriptional events, including regulation of the levels and phosphorylation state of translation factors. However, the mechanisms underlying clock control of translation initiation, and the impact of this potential regulation on rhythmic protein synthesis, were not known. We show that inhibitory phosphorylation of eIF2α (P-eIF2α), a conserved translation initiation factor, is clock controlled in Neurospora crassa, peaking during the subjective day. Cycling P-eIF2α levels required rhythmic activation of the eIF2α kinase CPC-3 (the homolog of yeast and mammalian GCN2), and rhythmic activation of CPC-3 was abolished under conditions in which the levels of charged tRNAs were altered. Clock-controlled accumulation of P-eIF2α led to reduced translation during the day in vitro and was necessary for the rhythmic synthesis of select proteins in vivo. Finally, loss of rhythmic P-eIF2α levels led to reduced linear growth rates, supporting the idea that partitioning translation to specific times of day provides a growth advantage to the organism. Together, these results reveal a fundamental mechanism by which the clock regulates rhythmic protein production, and provide key insights into how rhythmic translation, cellular energy, stress, and nutrient metabolism are linked through the levels of charged versus uncharged tRNAs.

Dynamic intersubject neural synchronization reflects affective responses to sad music.

Psychological theories of emotion often highlight the dynamic quality of the affective experience, yet neuroimaging studies of affect have traditionally relied on static stimuli that lack ecological validity. Consequently, the brain regions that represent emotions and feelings as they unfold remain unclear. Recently, dynamic, model-free analytical techniques have been employed with naturalistic stimuli to better capture time-varying patterns of activity in the brain; yet, few studies have focused on relating these patterns to changes in subjective feelings. Here, we address this gap, using intersubject correlation and phase synchronization to assess how stimulus-driven changes in brain activity and connectivity are related to two aspects of emotional experience: emotional intensity and enjoyment. During fMRI scanning, healthy volunteers listened to a full-length piece of music selected to induce sadness. After scanning, participants listened to the piece twice while simultaneously rating the intensity of felt sadness or felt enjoyment. Activity in the auditory cortex, insula, and inferior frontal gyrus was significantly synchronized across participants. Synchronization in auditory, visual, and prefrontal regions was significantly greater in participants with higher measures of a subscale of trait empathy related to feeling emotions in response to music. When assessed dynamically, continuous enjoyment ratings positively predicted a moment-to-moment measure of intersubject synchronization in auditory, default mode, and striatal networks, as well as the orbitofrontal cortex, whereas sadness predicted intersubject synchronization in limbic and striatal networks. The results suggest that stimulus-driven patterns of neural communication in emotional processing and high-level cortical regions carry meaningful information with regards to our feeling in response to a naturalistic stimulus.

Nostalgia and well-being in daily life: An ecological validity perspective.

Nostalgia is a mixed emotion. Recent empirical research, however, has highlighted positive effects of nostalgia, suggesting it is a predominantly positive emotion. When measured as an individual difference, nostalgia-prone individuals report greater meaning in life and approach temperament. When manipulated in an experimental paradigm, nostalgia increases meaning in life, self-esteem, optimism, and positive affect. These positive effects may result from the specific experimental procedures used and little is known about daily experiences that covary with nostalgia. To address this gap, we aimed to measure nostalgia in ecologically valid contexts. We created and validated the Personal Inventory of Nostalgic Experiences (PINE) scale (Studies 1a-1d) to assess both trait and state-based nostalgic experiences. When measured as an individual difference, the nomological net was generally negative (Study 2). When measured in daily life (Studies 3 and 4), nostalgia as a state variable was negatively related to well-being. Lagged analyses showed that state nostalgia had mixed effects on well-being at a later moment that day and negative effects on well-being on the following day. To reconcile the discrepancies between these studies and the positive effects of nostalgia from previous research, we showed that experimentally induced nostalgic recollections were rated more positively and less negatively than daily experiences of nostalgia (Study 5). These studies show that nostalgia is a mixed emotion; although it may be predominantly positive when nostalgic memories are generated on request, it seems predominantly negative when nostalgia is experienced in the course of everyday life. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Effects of Music Training on Inhibitory Control and Associated Neural Networks in School-Aged Children: A Longitudinal Study.

Inhibitory control, the ability to suppress an immediate dominant response, has been shown to predict academic and career success, socioemotional wellbeing, wealth, and physical health. Learning to play a musical instrument engages various sensorimotor processes and draws on cognitive capacities including inhibition and task switching. While music training has been shown to benefit cognitive and language skills, its impact on inhibitory control remains inconclusive. As part of an ongoing 5-year longitudinal study, we investigated the effects of music training on the development of inhibitory control and its neural underpinnings with a population of children (starting at age 6) from underserved communities. Children involved in music were compared with children involved in sports and children not involved in any systematic after-school program. Inhibition was measured using a delayed gratification, flanker, and Color-Word Stroop task, which was performed both inside and outside of an MRI scanner. We established that there were no pre-existing differences in cognitive capacities among the groups at the onset. In the delayed gratification task, beginning after 3 years of training, children with music training chose a larger, delayed reward in place of a smaller, immediate reward compared to the control group. In the flanker task, children in the music group, significantly improved their accuracy after 3 and 4 years of training, whereas such improvement in the sport and control group did not reach significance. There were no differences among the groups on behavioral measures of Color-Word Stroop task at any time point. As for differences in brain function, we have previously reported that after 2 years, children with music training showed significantly greater bilateral activation in the pre-SMA/SMA, ACC, IFG, and insula during the Color-Word Stroop task compared to the control group, but not compared to the sports group (Sachs et al., 2017). However, after 4 years, we report here that differences in brain activity related to the Color-Word Stroop task between musicians and the other groups is only observed in the right IFG. The results suggest that systematic extracurricular programs, particularly music-based training, may accelerate development of inhibitory control and related brain networks earlier in childhood.

eRF1 mediates codon usage effects on mRNA translation efficiency through premature termination at rare codons.

Codon usage bias is a universal feature of eukaryotic and prokaryotic genomes and plays an important role in regulating gene expression levels. A major role of codon usage is thought to regulate protein expression levels by affecting mRNA translation efficiency, but the underlying mechanism is unclear. By analyzing ribosome profiling results, here we showed that codon usage regulates translation elongation rate and that rare codons are decoded more slowly than common codons in all codon families in Neurospora. Rare codons resulted in ribosome stalling in manners both dependent and independent of protein sequence context and caused premature translation termination. This mechanism was shown to be conserved in Drosophila cells. In both Neurospora and Drosophila cells, codon usage plays an important role in regulating mRNA translation efficiency. We found that the rare codon-dependent premature termination is mediated by the translation termination factor eRF1, which recognizes ribosomes stalled on rare sense codons. Silencing of eRF1 expression resulted in codon usage-dependent changes in protein expression. Together, these results establish a mechanism for how codon usage regulates mRNA translation efficiency.