Impact of hydrogen peroxide on the activity, structure, and conformational stability of the oxidized protein repair enzyme methionine sulfoxide reductase A.

International audienceThe oxidized protein repair methionine sulfoxide reductase (Msr) system has been implicated in aging, in longevity, and in the protection against oxidative stress. This system is made of two different enzymes (MsrA and MsrB) that catalyze the reduction of the two diastereoisomers S- and R-methionine sulfoxide back to methionine within proteins, respectively. Due to its role in cellular protection against oxidative stress that is believed to originate from its reactive oxygen species scavenging ability in combination with exposed methionine at the surface of proteins, the susceptibility of MsrA to hydrogen-peroxide-mediated oxidative inactivation has been analyzed. This study is particularly relevant to the oxidized protein repair function of MsrA in both fighting against oxidized protein formation and being exposed to oxidative stress situations. The enzymatic properties of MsrA indeed rely on the activation of the catalytic cysteine to the thiolate anion form that is potentially susceptible to oxidation by hydrogen peroxide. The residual activity and the redox status of the catalytic cysteine were monitored before and after treatment. These experiments showed that the enzyme is only inactivated by high doses of hydrogen peroxide. Although no significant structural modification was detected by near- and far-UV circular dichroism, the conformational stability of oxidized MsrA was decreased as compared to that of native MsrA, making it more prone to degradation by the 20S proteasome. Decreased conformational stability of oxidized MsrA may therefore be considered as a key factor for determining its increased susceptibility to degradation by the proteasome, hence avoiding its intracellular accumulation upon oxidative stress

Global host molecular perturbations upon in situ loss of bacterial endosymbionts in the deep-sea mussel Bathymodiolus azoricus assessed using proteomics and transcriptomics

Background: Colonization of deep-sea hydrothermal vents by most invertebrates was made efficient through their adaptation to a symbiotic lifestyle with chemosynthetic bacteria, the primary producers in these ecosystems. Anatomical adaptations such as the establishment of specialized cells or organs have been evidenced in numerous deep-sea invertebrates. However, very few studies detailed global inter-dependencies between host and symbionts in these ecosystems. In this study, we proposed to describe, using a proteo-transcriptomic approach, the effects of symbionts loss on the deep-sea mussel Bathymodiolus azoricus' molecular biology. We induced an in situ depletion of symbionts and compared the proteo-transcriptome of the gills of mussels in three conditions: symbiotic mussels (natural population), symbiont-depleted mussels and aposymbiotic mussels. Results: Global proteomic and transcriptomic results evidenced a global disruption of host machinery in aposymbiotic organisms. We observed that the total number of proteins identified decreased from 1118 in symbiotic mussels to 790 in partially depleted mussels and 761 in aposymbiotic mussels. Using microarrays we identified 4300 transcripts differentially expressed between symbiont-depleted and symbiotic mussels. Among these transcripts, 799 were found differentially expressed in aposymbiotic mussels and almost twice as many in symbiont-depleted mussels as compared to symbiotic mussels. Regarding apoptotic and immune system processes - known to be largely involved in symbiotic interactions - an overall up-regulation of associated proteins and transcripts was observed in symbiont-depleted mussels. Conclusion: Overall, our study showed a global impairment of host machinery and an activation of both the immune and apoptotic system following symbiont-depletion. One of the main assumptions is the involvement of symbiotic bacteria in the inhibition and regulation of immune and apoptotic systems. As such, symbiotic bacteria may increase their lifespan in gill cells while managing the defense of the holobiont against putative pathogens

Proteomic analysis of major and minor allergens from isolated pollen cytoplasmic granules.

International audienceGrass pollen is one of the most important vectors of aeroallergens. Under atmospheric conditions, pollen grains can release pollen cytoplasmic granules (PCGs). The allergens associated with these intrinsic subfractions induce, in laboratory animals as well as in asthmatic patients, allergic and inflammatory responses. The objectives of this study were to characterize the PCGs' intrinsic allergens and to compare them with those of pollen grains. The water-soluble proteins were extracted from pollen grains and their PCGs. IgE-binding proteins were analyzed and characterized through an allergomic strategy: 1- and 2-dimensional gel electrophoresis (1-DE and 2-DE), immunoblotting, using grass-pollen-sensitized patient sera, mass spectrometry (MS) analysis, and database searching. Several of the allergens listed in the IUIS nomenclature, Phl p 1, 4, 5, 6, and 12, were detected in pollen and PCG extracts, whereas Phl p 11 was found only in PCGs, and Phl p 2 as well as Phl p 13 were found only in pollen extract. Some other allergens not listed in the IUIS nomenclature were also characterized in both pollen and PCG extracts. Since the major grass pollen allergens were found in PCGs and because of their small size, these submicronic particles should be considered as very potent sensitizing and challenging respirable vectors of allergens

Highly cytotoxic and neurotoxic acetogenins of the Annonaceae: New putative biological targets of squamocin detected by activity-based protein profiling.

International audienceAcetogenins of the Annonaceae are strong inhibitors of mitochondrial complex I but discrepancies in the structure/activity relationships pled the search for other targets within the whole cell proteome. Combining hemisynthetic work, Cu-catalyzed Huisgen cycloaddition and proteomic techniques we have identified new putative protein targets of squamocin ruling out the previously accepted 'complex I dogma'. These results give new insights into the mechanism of action of these potent neurotoxic molecules

Proteomic Analysis of Major and Minor Allergens from Isolated Pollen Cytoplasmic Granules

Grass pollen is one of the most important vectors of aeroallergens. Under atmospheric conditions, pollen grains can release pollen cytoplasmic granules (PCGs). The allergens associated with these intrinsic subfractions induce, in laboratory animals as well as in asthmatic patients, allergic and inflammatory responses. The objectives of this study were to characterize the PCGs' intrinsic allergens and to compare them with those of pollen grains. The water-soluble proteins were extracted from pollen grains and their PCGs. IgE-binding proteins were analyzed and characterized through an allergomic strategy: 1- and 2-dimensional gel electrophoresis (1-DE and 2-DE), immunoblotting, using grass-pollen-sensitized patient sera, mass spectrometry (MS) analysis, and database searching. Several of the allergens listed in the IUIS nomenclature, Phl p 1, 4, 5, 6, and 12, were detected in pollen and PCG extracts, whereas Phl p 11 was found only in PCGs, and Phl p 2 as well as Phl p 13 were found only in pollen extract. Some other allergens not listed in the IUIS nomenclature were also characterized in both pollen and PCG extracts. Since the major grass pollen allergens were found in PCGs and because of their small size, these submicronic particles should be considered as very potent sensitizing and challenging respirable vectors of allergens

Proteomic Analysis of Major and Minor Allergens from Isolated Pollen Cytoplasmic Granules

Grass pollen is one of the most important vectors of aeroallergens. Under atmospheric conditions, pollen grains can release pollen cytoplasmic granules (PCGs). The allergens associated with these intrinsic subfractions induce, in laboratory animals as well as in asthmatic patients, allergic and inflammatory responses. The objectives of this study were to characterize the PCGs' intrinsic allergens and to compare them with those of pollen grains. The water-soluble proteins were extracted from pollen grains and their PCGs. IgE-binding proteins were analyzed and characterized through an allergomic strategy: 1- and 2-dimensional gel electrophoresis (1-DE and 2-DE), immunoblotting, using grass-pollen-sensitized patient sera, mass spectrometry (MS) analysis, and database searching. Several of the allergens listed in the IUIS nomenclature, Phl p 1, 4, 5, 6, and 12, were detected in pollen and PCG extracts, whereas Phl p 11 was found only in PCGs, and Phl p 2 as well as Phl p 13 were found only in pollen extract. Some other allergens not listed in the IUIS nomenclature were also characterized in both pollen and PCG extracts. Since the major grass pollen allergens were found in PCGs and because of their small size, these submicronic particles should be considered as very potent sensitizing and challenging respirable vectors of allergens

Tau pathology modulates Pin1 post-translational modifications and may be relevant as biomarker.

A prerequisite to dephosphorylation at Ser-Pro or Thr-Pro motifs is the isomerization of the imidic peptide bond preceding the proline. The peptidyl-prolyl cis/trans isomerase named Pin1 catalyzes this mechanism. Through isomerization, Pin1 regulates the function of a growing number of targets including the microtubule-associated tau protein and is supposed to be deregulated Alzheimer's disease (AD). Using proteomics, we showed that Pin1 is posttranslationally modified on more than 5 residues, comprising phosphorylation, N-acetylation, and oxidation. Although Pin1 expression remained constant, Pin1 posttranslational two-dimensional pattern was modified by tau overexpression in a tau-inducible neuroblastoma cell line, in our THY-Tau22 mouse model of tauopathy as well as in AD. Interestingly, in all of these systems, Pin1 modifications were very similar. In AD brain tissue when compared with control, Pin1 is hyperphosphorylated at serine 16 and found in the most insoluble hyperphosphorylated tau fraction of AD brain tissue. Furthermore, in all tau pathology conditions, acetylation of Pin1 may also contribute to the differences observed. In conclusion, Pin1 displays several posttranslational modifications, which are specific in tauopathies and may be useful as biomarker.info:eu-repo/semantics/publishe

SARS-CoV-2 Infection in Children Less Than Forty Days Hospitalized in Belgium Between 2020 and 2022.

Our study aimed to assess the severity of severe acute respiratory syndrome coronavirus 2 infection in hospitalized infants under 40 days old, across 21 Belgian hospitals between 2020 and 2022. Of the 365 infants studied, 14.2% needed respiratory support. The median hospital stay was 3 days (interquartile range, 2-4), and there were no deaths. Infection severity was similar during the Omicron and Alpha/Delta periods