Educational interventions for the prevention and management of adverse events following immunisation: a systematic review. / Intervenções educativas para prevenção e conduta dos eventos adversos pós-vacinação: uma revisão sistemática.

This study investigated educational interventions for the prevention and management of adverse events following immunisation. This a systematic review was conducted by examining observational studies, with no restriction as to language or year, registered in PROSPERO with the identifier CRD42022313144 and by searching the MEDLINE, LILACS, Embase, CINAHL and Scopus databases. Two researchers selected the studies, extracted the data and assessed the risk of study bias; disagreements were resolved by a third researcher. A total of six articles met the inclusion criteria of the systematic review and the studies reported significant post-intervention improvements in staff conduct in relation to immunisation. It was concluded that educational strategies that lead to continued professional development in relation to vaccination in primary care were effective in reducing and/or eradicating immunisation errors and adverse events following immunisation.

O estudo tem como objetivo investigar as intervenções educativas para a prevenção e conduta dos eventos adversos pós-vacinação. Trata-se de uma revisão sistemática realizada por meio da análise de estudos observacionais sem restrição de idioma e ano com registro no PROSPERO pelo identificador CRD42022313144 e busca nas bases de dados MEDLINE, LILACS, Embase, CINAHL e Scopus. Dois pesquisadores selecionaram os estudos, extraíram os dados e avaliaram o risco de viés, as discordâncias foram resolvidas por um terceiro pesquisador. Atenderam os critérios de inclusão da revisão sistemática um total de seis artigos e os estudos apresentaram melhoras significativas pós-intervenção na conduta dos profissionais em relação à imunização. Conclui-se que o fornecimento de estratégias educativas de educação permanente no âmbito vacinal da atenção primária é eficaz para reduzir e/ou erradicar os erros de imunização e eventos adversos pós-vacinação.

Exploring the Reaction Mechanism of Polyethylene Terephthalate Biodegradation through QM/MM Approach.

The enzyme PETase fromIdeonella sakaiensis (IsPETase) strain 201-F6 can catalyze the hydrolysis of polyethylene terephthalate (PET), mainly converting it into mono(2-hydroxyethyl) terephthalic acid (MHET). In this study, we used quantum mechanics/molecular mechanics (QM/MM) simulations to explore the molecular details of the catalytic reaction mechanism of IsPETase in the formation of MHET. The QM region was described with AM1d/PhoT and M06-2X/6-31+G(d,p) potential. QM/MM simulations unveil the complete enzymatic PET hydrolysis mechanism and identify two possible reaction pathways for acylation and deacylation steps. The barrier obtained at M06-2X/6-31+G(d,p)/MM potential for the deacylation step corresponds to 20.4 kcal/mol, aligning with the experimental value of 18 kcal/mol. Our findings indicate that deacylation is the rate-limiting step of the process. Furthermore, per-residue interaction energy contributions revealed unfavorable contributions to the transition state of amino acids located at positions 200-230, suggesting potential sites for targeted mutations. These results can contribute to the development of more active and selective enzymes for PET depolymerization.

Anti-Leishmania activity and molecular docking of unusual flavonoids-rich fraction from Arrabidaea brachypoda (Bignoniaceae).

Leishmaniases comprise a group of infectious parasitic diseases caused by various species of Leishmania and are considered a significant public health problem worldwide. Only a few medications, including miltefosine, amphotericin B, and meglumine antimonate, are used in current therapy. These medications are associated with severe side effects, low efficacy, high cost, and the need for hospital support. Additionally, there have been occurrences of drug resistance. Additionally, only a limited number of drugs, such as meglumine antimonate, amphotericin B, and miltefosine, are available, all of which are associated with severe side effects. In this context, the need for new effective drugs with fewer adverse effects is evident. Therefore, this study investigated the anti-Leishmania activity of a dichloromethane fraction (DCMF) extracted from Arrabidaea brachypoda roots. This fraction inhibited the viability of L. infantum, L. braziliensis, and L. Mexicana promastigotes, with IC50 values of 10.13, 11.44, and 11.16 µg/mL, respectively, and against L. infantum amastigotes (IC50 = 4.81 µg/mL). Moreover, the DCMF exhibited moderate cytotoxicity (CC50 = 25.15) towards RAW264.7 macrophages, with a selectivity index (SI) of 5.2. Notably, the DCMF caused damage to the macrophage genome only at 40 µg/mL, which is greater than the IC50 found for all Leishmania species. The results suggest that DCMF demonstrates similar antileishmanial effectiveness to isolated brachydin B, without causing genotoxic effects on mammalian cells. This finding is crucial because the isolation of the compounds relies on several steps and is very costly while obtaining the DCMF fraction is a simple and cost-effective process. Furthermore, In addition, the potential mechanisms of action of brachydins were also investigated. The computational analysis indicates that brachydin compounds bind to the Triosephosphate isomerase (TIM) enzyme via two main mechanisms: destabilizing the interface between the homodimers and interacting with catalytic residues situated at the site of binding. Based on all the results, DCMF exhibits promise as a therapeutic agent for leishmaniasis due to its significantly reduced toxicity in comparison to the adverse effects associated with current reference treatments.

An integrated view of cisplatin-induced nephrotoxicity, hepatotoxicity, and cardiotoxicity: characteristics, common molecular mechanisms, and current clinical management.

Cisplatin (CP) is a chemotherapy drug widely prescribed to treat various neoplasms. Although fundamental for the therapeutic action of the drug, its cytotoxic mechanisms trigger adverse effects in several tissues, such as the kidney, liver, and heart, which limit its clinical use. In this sense, studies point to an essential role of damage to nuclear and mitochondrial DNA associated with oxidative stress, inflammation, and apoptosis in the pathophysiology of tissue injuries. Due to the limitation of effective preventive and therapeutic measures against CP-induced toxicity, new strategies with potential cytoprotective effects have been studied. Therefore, this article is timely in reviewing the characteristics and main molecular mechanisms common to renal, hepatic, and cardiac toxicity previously described, in addition to addressing the main validated strategies for the current management of these adverse events in clinical practice. We also handle the main promising antioxidant substances recently presented in the literature to encourage the development of new research that consolidates their potential preventive and therapeutic effects against CP-induced cytotoxicity.

Oncogenic mutations of KRAS modulate its turnover by the CUL3/LZTR1 E3 ligase complex.

KRAS is a proto-oncogene encoding a small GTPase. Mutations contribute to ∼30% of human solid tumours, including lung adenocarcinoma, pancreatic, and colorectal carcinomas. Most KRAS activating mutations interfere with GTP hydrolysis, essential for its role as a molecular switch, leading to alterations in their molecular environment and oncogenic signalling. However, the precise signalling cascades these mutations affect are poorly understood. Here, APEX2 proximity labelling was used to profile the molecular environment of WT, G12D, G13D, and Q61H-activating KRAS mutants under starvation and stimulation conditions. Through quantitative proteomics, we demonstrate the presence of known KRAS interactors, including ARAF and LZTR1, which are differentially captured by WT and KRAS mutants. Notably, the KRAS mutations G12D, G13D, and Q61H abrogate their association with LZTR1, thereby affecting turnover. Elucidating the implications of LZTR1-mediated regulation of KRAS protein levels in cancer may offer insights into therapeutic strategies targeting KRAS-driven malignancies.

Thermostability Enhancement of GH 62 α-l-Arabinofuranosidase by Directed Evolution and Rational Design.

GH 62 arabinofuranosidases are known for their excellent specificity for arabinoxylan of agroindustrial residues and their synergism with endoxylanases and other hemicellulases. However, the low thermostability of some GH enzymes hampers potential industrial applications. Protein engineering research highly desires mutations that can enhance thermostability. Therefore, we employed directed evolution using one round of error-prone PCR and site-saturation mutagenesis for thermostability enhancement of GH 62 arabinofuranosidase from Aspergillus fumigatus. Single mutants with enhanced thermostability showed significant ΔΔG changes (<-2.5 kcal/mol) and improvements in perplexity scores from evolutionary scale modeling inverse folding. The best mutant, G205K, increased the melting temperature by 5 °C and the energy of denaturation by 41.3%. We discussed the functional mechanisms for improved stability. Analyzing the adjustments in α-helices, ß-sheets, and loops resulting from point mutations, we have obtained significant knowledge regarding the potential impacts on protein stability, folding, and overall structural integrity.

Intervenções educativas para prevenção e conduta dos eventos adversos pós-vacinação: uma revisão sistemática / Educational interventions for the prevention and management of adverse events following immunisation: a systematic review

Resumo O estudo tem como objetivo investigar as intervenções educativas para a prevenção e conduta dos eventos adversos pós-vacinação. Trata-se de uma revisão sistemática realizada por meio da análise de estudos observacionais sem restrição de idioma e ano com registro no PROSPERO pelo identificador CRD42022313144 e busca nas bases de dados MEDLINE, LILACS, Embase, CINAHL e Scopus. Dois pesquisadores selecionaram os estudos, extraíram os dados e avaliaram o risco de viés, as discordâncias foram resolvidas por um terceiro pesquisador. Atenderam os critérios de inclusão da revisão sistemática um total de seis artigos e os estudos apresentaram melhoras significativas pós-intervenção na conduta dos profissionais em relação à imunização. Conclui-se que o fornecimento de estratégias educativas de educação permanente no âmbito vacinal da atenção primária é eficaz para reduzir e/ou erradicar os erros de imunização e eventos adversos pós-vacinação.

Abstract This study investigated educational interventions for the prevention and management of adverse events following immunisation. This a systematic review was conducted by examining observational studies, with no restriction as to language or year, registered in PROSPERO with the identifier CRD42022313144 and by searching the MEDLINE, LILACS, Embase, CINAHL and Scopus databases. Two researchers selected the studies, extracted the data and assessed the risk of study bias; disagreements were resolved by a third researcher. A total of six articles met the inclusion criteria of the systematic review and the studies reported significant post-intervention improvements in staff conduct in relation to immunisation. It was concluded that educational strategies that lead to continued professional development in relation to vaccination in primary care were effective in reducing and/or eradicating immunisation errors and adverse events following immunisation.

Nutrition and Exercise for Wellness and Recovery: A Randomized Controlled Trial of a Community-Based Health Intervention.

OBJECTIVE: The purpose of this study was to examine the efficacy of the Nutrition and Exercise for Wellness and Recovery (NEW-R) intervention for improving competency and behaviors related to diet, physical activity, and weight management. METHODS: Participants with psychiatric disabilities were recruited from four community mental health agencies and a hospital-based psychiatric outpatient clinic and randomly assigned to the NEW-R intervention (N=55) or control condition (N=58). Outcome measures included the Perceived Competence Scale, Health-Promoting Lifestyle Profile (HPLP), and weight change; random-effects regression models were used. A follow-up analysis examined the interactions of group, time, and site. RESULTS: Fifty of the 55 intervention participants and 57 of the 58 control participants completed the study. The two groups did not differ significantly on any measured baseline characteristic. The intervention group had statistically significant improvements, compared with the control group, in perceived competence for exercise and healthy eating, total HPLP score, and scores on two HPLP subscales (nutrition and spiritual growth). No significant difference between groups was found for weight loss. A study condition × time × site effect was observed: at the three sites where mean weight loss occurred, NEW-R participants lost significantly more weight than did control participants. CONCLUSIONS: NEW-R offers promise as an intervention that can initiate the change to healthy lifestyle behaviors and boost perceived competence in a healthy lifestyle. It may also be effective for weight loss when administered in supportive settings.

COVID-19 and Acute Kidney Injury - Direct and Indirect Pathophysiological Mechanisms Underlying Lesion Development.

COVID-19 is a pandemic disease caused by the SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) responsible for millions of deaths worldwide. Although the respiratory system is the main target of COVID-19, the disease can affect other organs, including the kidneys. Acute Kidney Injury (AKI), commonly seen in patients infected with COVID-19, has a multifactorial cause. Several studies associate this injury with the direct involvement of the virus in renal cells and the indirect damage stimulated by the infection. The direct cytopathic effects of SARS-CoV-2 are due to the entry and replication of the virus in renal cells, changing several regulatory pathways, especially the renin-angiotensin-aldosterone system (RAAS), with repercussions on the kallikrein-kinin system (KKS). Furthermore, the virus can deregulate the immune system, leading to an exaggerated response of inflammatory cells, characterizing the state of hypercytokinemia. The such exaggerated inflammatory response is commonly associated with hemodynamic changes, reduced renal perfusion, tissue hypoxia, generation of reactive oxygen species (ROS), endothelial damage, and coagulopathies, which can result in severe damage to the renal parenchyma. Thereby, understanding the molecular mechanisms and pathophysiology of kidney injuries induced by SARS-COV-2 is of fundamental importance to obtaining new therapeutic insights for the prevention and management of AKI.

Assessment of Reversibility for Covalent Cysteine Protease Inhibitors Using Quantum Mechanics/Molecular Mechanics Free Energy Surfaces.

We have used molecular dynamics (MD) simulations with hybrid quantum mechanics/molecular mechanics (QM/MM) potentials to investigate the reaction mechanism for covalent inhibition of cathepsin K and assess the reversibility of inhibition. The computed free energy profiles suggest that a nucleophilic attack by the catalytic cysteine on the inhibitor warhead and proton transfer from the catalytic histidine occur in a concerted manner. The results indicate that the reaction is more strongly exergonic for the alkyne-based inhibitors, which bind irreversibly to cathepsin K, than for the nitrile-based inhibitor odanacatib, which binds reversibly. Gas-phase energies were also calculated for the addition of methanethiol to structural prototypes for a number of warheads of interest in cysteine protease inhibitor design in order to assess electrophilicity. The approaches presented in this study are particularly applicable to assessment of novel warheads, and computed transition state geometries can be incorporated into molecular models for covalent docking.

Noninvasive proteomic biomarkers for alcohol-related liver disease.

Alcohol-related liver disease (ALD) is a major cause of liver-related death worldwide, yet understanding of the three key pathological features of the disease-fibrosis, inflammation and steatosis-remains incomplete. Here, we present a paired liver-plasma proteomics approach to infer molecular pathophysiology and to explore the diagnostic and prognostic capability of plasma proteomics in 596 individuals (137 controls and 459 individuals with ALD), 360 of whom had biopsy-based histological assessment. We analyzed all plasma samples and 79 liver biopsies using a mass spectrometry (MS)-based proteomics workflow with short gradient times and an enhanced, data-independent acquisition scheme in only 3 weeks of measurement time. In plasma and liver biopsy tissues, metabolic functions were downregulated whereas fibrosis-associated signaling and immune responses were upregulated. Machine learning models identified proteomics biomarker panels that detected significant fibrosis (receiver operating characteristic-area under the curve (ROC-AUC), 0.92, accuracy, 0.82) and mild inflammation (ROC-AUC, 0.87, accuracy, 0.79) more accurately than existing clinical assays (DeLong's test, P < 0.05). These biomarker panels were found to be accurate in prediction of future liver-related events and all-cause mortality, with a Harrell's C-index of 0.90 and 0.79, respectively. An independent validation cohort reproduced the diagnostic model performance, laying the foundation for routine MS-based liver disease testing.

Deep Visual Proteomics defines single-cell identity and heterogeneity.

Despite the availabilty of imaging-based and mass-spectrometry-based methods for spatial proteomics, a key challenge remains connecting images with single-cell-resolution protein abundance measurements. Here, we introduce Deep Visual Proteomics (DVP), which combines artificial-intelligence-driven image analysis of cellular phenotypes with automated single-cell or single-nucleus laser microdissection and ultra-high-sensitivity mass spectrometry. DVP links protein abundance to complex cellular or subcellular phenotypes while preserving spatial context. By individually excising nuclei from cell culture, we classified distinct cell states with proteomic profiles defined by known and uncharacterized proteins. In an archived primary melanoma tissue, DVP identified spatially resolved proteome changes as normal melanocytes transition to fully invasive melanoma, revealing pathways that change in a spatial manner as cancer progresses, such as mRNA splicing dysregulation in metastatic vertical growth that coincides with reduced interferon signaling and antigen presentation. The ability of DVP to retain precise spatial proteomic information in the tissue context has implications for the molecular profiling of clinical samples.

Dynamic human liver proteome atlas reveals functional insights into disease pathways.

Deeper understanding of liver pathophysiology would benefit from a comprehensive quantitative proteome resource at cell type resolution to predict outcome and design therapy. Here, we quantify more than 150,000 sequence-unique peptides aggregated into 10,000 proteins across total liver, the major liver cell types, time course of primary cell cultures, and liver disease states. Bioinformatic analysis reveals that half of hepatocyte protein mass is comprised of enzymes and 23% of mitochondrial proteins, twice the proportion of other liver cell types. Using primary cell cultures, we capture dynamic proteome remodeling from tissue states to cell line states, providing useful information for biological or pharmaceutical research. Our extensive data serve as spectral library to characterize a human cohort of non-alcoholic steatohepatitis and cirrhosis. Dramatic proteome changes in liver tissue include signatures of hepatic stellate cell activation resembling liver cirrhosis and providing functional insights. We built a web-based dashboard application for the interactive exploration of our resource (www.liverproteome.org).

A knowledge graph to interpret clinical proteomics data.

Implementing precision medicine hinges on the integration of omics data, such as proteomics, into the clinical decision-making process, but the quantity and diversity of biomedical data, and the spread of clinically relevant knowledge across multiple biomedical databases and publications, pose a challenge to data integration. Here we present the Clinical Knowledge Graph (CKG), an open-source platform currently comprising close to 20 million nodes and 220 million relationships that represent relevant experimental data, public databases and literature. The graph structure provides a flexible data model that is easily extendable to new nodes and relationships as new databases become available. The CKG incorporates statistical and machine learning algorithms that accelerate the analysis and interpretation of typical proteomics workflows. Using a set of proof-of-concept biomarker studies, we show how the CKG might augment and enrich proteomics data and help inform clinical decision-making.

Defining NASH from a Multi-Omics Systems Biology Perspective.

Non-alcoholic steatohepatitis (NASH) is a chronic liver disease affecting up to 6.5% of the general population. There is no simple definition of NASH, and the molecular mechanism underlying disease pathogenesis remains elusive. Studies applying single omics technologies have enabled a better understanding of the molecular profiles associated with steatosis and hepatic inflammation-the commonly accepted histologic features for diagnosing NASH, as well as the discovery of novel candidate biomarkers. Multi-omics analysis holds great potential to uncover new insights into disease mechanism through integrating multiple layers of molecular information. Despite the technical and computational challenges associated with such efforts, a few pioneering studies have successfully applied multi-omics technologies to investigate NASH. Here, we review the most recent technological developments in mass spectrometry (MS)-based proteomics, metabolomics, and lipidomics. We summarize multi-omics studies and emerging omics biomarkers in NASH and highlight the biological insights gained through these integrated analyses.

Age-dependent changes in protein incorporation into collagen-rich tissues of mice by in vivo pulsed SILAC labelling.

Collagen-rich tissues have poor reparative capacity that predisposes to common age-related disorders such as osteoporosis and osteoarthritis. We used in vivo pulsed SILAC labelling to quantify new protein incorporation into cartilage, bone, and skin of mice across the healthy life course. We report dynamic turnover of the matrisome, the proteins of the extracellular matrix, in bone and cartilage during skeletal maturation, which was markedly reduced after skeletal maturity. Comparing young adult with older adult mice, new protein incorporation was reduced in all tissues. STRING clustering revealed changes in epigenetic modulators across all tissues, a decline in chondroprotective growth factors such as FGF2 and TGFß in cartilage, and clusters indicating mitochondrial dysregulation and reduced collagen synthesis in bone. Several pathways were implicated in age-related disease. Fewer changes were observed for skin. This methodology provides dynamic protein data at a tissue level, uncovering age-related molecular changes that may predispose to disease.

Characterization and Analysis of the Carbonation Process of a Lime Mortar Obtained from Phosphogypsum Waste.

This work addresses the reuse of waste products as a raw material for lime putties, which are one of the components of mortar. 1:3 Lime/sand mortars very similar to conventional construction mortars were prepared using a lime putty obtained from the treatment of phosphogypsum with sodium hydroxide. The physical, rheological and mechanical properties of this phosphogypsum-derived mortar have been studied, as well as the mineralogical composition, microstructure by scanning electron microscope (SEM) and curing process by monitoring carbonation and ultrasonic propagation velocity. Considering the negative influence of sulphates on the hardened material, the behaviour of the material after sulphates precipitation by adding barium sulphate was additionally tested. Carbonation progressed from the outside to the inside of the specimen through the porous system by Liesegang rings patterns for mortars with soluble sulphates, while the carbonation with precipitated sulphates was controlled by diffusion-precipitation. Overall, the negative influence of low-sulphate contents on the mechanical properties of mortars was verified. It must be highlighted the importance of their precipitation to obtain adequate performance.

Febre Amarela: Representação Imagética de uma Epidemia no Rio De Janeiro no Século XIX / Fiebre Amarilla: Representación en imágenes de una epidemia en el Río de Janeiro del Siglo XIX / Yellow Fever: Imagetic Representation of an Epidemic in Rio De Janeiro in the 19th Century

Objetivo: analizar la imagen sobre la epidemia de Fiebre Amarilla en Río de Janeiro, en1850. Metodología: Se trata de un estudio en la perspectiva histórica, con base en análisis culturaly em imaginería. La fuente histórica fue la imagen de la décima tirada de la Revista Illustrada, en1876. Resultados: La imagen publicada el día 04 de marzo de 1876, en la página 07 del número10 del Año 01 de la Revista Ilustrada, denominada "Epidemia de la Fiebre Amarilla" como unbrote que causó altas tasas de mortalidad, representaciones sobre la dinámica de la epidemia, lamuerte, y la participación de Oswaldo Cruz en este contexto. Conclusiones: Las representaciones,en conjunto, demostraron la desesperación con la enfermedad, la muerte como desenlace de estaepidemia y acción sanitaria, pero también la esperanza y salvación por medio de la vacuna comodesdoblamiento de este brote.(AU)

Objective: to analyze the image about the Yellow Fever epidemic in Rio de Janeiro in 1850.Methodology: This is a historical perspective, based on cultural and imagery analysis. Thehistorical source was the image of the tenth issue of Illustrada Magazine, in 1876. Results: Theimage published on March 4, 1876, on page 07 of the number 10 of Year 01 of Revista Ilustrada,denominated "Yellow Fever Epidemic" translates as an outbreak that caused high mortality rates,representations on the dynamics of the epidemic, death, and Oswaldo Cruz's participation in thiscontext. Conclusions: The representations, together, demonstrated the despair with the disease, thedeath as an outcome of this epidemic and sanitary action, but also the hope and salvation throughthe vaccine as a result of this outbreak.(AU)

Objetivo: analisar a imagem sobre a epidemia de Febre Amarela no Rio de Janeiro, em1850. Metodologia: Trata-se de um estudo na perspectiva histórica, com base em análise culturale imagética. A fonte histórica foi a imagem da décima tiragem da Revista Illustrada, em 1876.Resultados: A imagem publicada no dia 04 de março de 1876, na página 07 do número 10 do Ano01 da Revista Ilustrada, denominada “Epidemia da Febre Amarela” traduz como um surto quecausou altas taxas de mortalidade, representações sobre a dinâmica da epidemia, a morte, e aparticipação de Oswaldo Cruz neste contexto. Conclusões: As representações, em conjunto,demonstraram o desespero com a doença, a morte como desfecho desta epidemia e ação sanitária,mas também a esperança e salvação por meio da vacina como desdobramento deste surto.(AU)

Glioblastoma multiforme: a multi-omics analysis of driver genes and tumour heterogeneity.

Glioblastoma (GBM) is the most aggressive and common brain cancer in adults with the lowest life expectancy. The current neuro-oncology practice has incorporated genes involved in key molecular events that drive GBM tumorigenesis as biomarkers to guide diagnosis and design treatment. This study summarizes findings describing the significant heterogeneity of GBM at the transcriptional and genomic levels, emphasizing 18 driver genes with clinical relevance. A pattern was identified fitting the stem cell model for GBM ontogenesis, with an upregulation profile for MGMT and downregulation for ATRX, H3F3A, TP53 and EGFR in the mesenchymal subtype. We also detected overexpression of EGFR, NES, VIM and TP53 in the classical subtype and of MKi67 and OLIG2 genes in the proneural subtype. Furthermore, we found a combination of the four biomarkers EGFR, NES, OLIG2 and VIM with a remarkable differential expression pattern which confers them a strong potential to determine the GBM molecular subtype. A unique distribution of somatic mutations was found for the young and adult population, particularly for genes related to DNA repair and chromatin remodelling, highlighting ATRX, MGMT and IDH1. Our results also revealed that highly lesioned genes undergo differential regulation with particular biological pathways for young patients. This multi-omic analysis will help delineate future strategies related to the use of these molecular markers for clinical decision-making in the medical routine.

Assessment of the PETase conformational changes induced by poly(ethylene terephthalate) binding.

Recently, a bacterium strain of Ideonella sakaiensis was identified with the uncommon ability to degrade the poly(ethylene terephthalate) (PET). The PETase from I. sakaiensis strain 201-F6 (IsPETase) catalyzes the hydrolysis of PET converting it to mono(2-hydroxyethyl) terephthalic acid (MHET), bis(2-hydroxyethyl)-TPA (BHET), and terephthalic acid (TPA). Despite the potential of this enzyme for mitigation or elimination of environmental contaminants, one of the limitations of the use of IsPETase for PET degradation is the fact that it acts only at moderate temperature due to its low thermal stability. Besides, molecular details of the main interactions of PET in the active site of IsPETase remain unclear. Herein, molecular docking and molecular dynamics (MD) simulations were applied to analyze structural changes of IsPETase induced by PET binding. Results from the essential dynamics revealed that the ß1-ß2 connecting loop is very flexible. This loop is located far from the active site of IsPETase and we suggest that it can be considered for mutagenesis to increase the thermal stability of IsPETase. The free energy landscape (FEL) demonstrates that the main change in the transition between the unbound to the bound state is associated with the ß7-α5 connecting loop, where the catalytic residue Asp206 is located. Overall, the present study provides insights into the molecular binding mechanism of PET into the IsPETase structure and a computational strategy for mapping flexible regions of this enzyme, which can be useful for the engineering of more efficient enzymes for recycling plastic polymers using biological systems.