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Projeto de investigação
Molecular, Structural and Cellular Microbiology – Instituto de Tecnologia Química e Biológica António Xavier
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Publicações
Unveiling molecular details behind improved activity at neutral to alkaline pH of an engineered DyP-type peroxidase
Publication . Borges, Patrícia T.; Silva, Diogo; Silva, Tomás F.D.; Brissos, Vânia; Cañellas, Marina; Lucas, Maria Fátima; Masgrau, Laura; Melo, Eduardo; Machuqueiro, Miguel; Frazão, Carlos; Martins, Lígia O.
DyP-type peroxidases (DyPs) are microbial enzymes that catalyze the oxidation of a wide range of substrates, including synthetic dyes, lignin-derived compounds, and metals, such as Mn2+ and Fe2+, and have enormous biotechnological potential in biorefineries. However, many questions on the molecular basis of enzyme function and stability remain unanswered. In this work, high-resolution structures of PpDyP wild-type and two engineered variants (6E10 and 29E4) generated by directed evolution were obtained. The X-ray crystal structures revealed the typical ferredoxin-like folds, with three heme access pathways, two tunnels, and one cavity, limited by three long loops including catalytic residues. Variant 6E10 displays significantly increased loops' flexibility that favors function over stability: despite the considerably higher catalytic efficiency, this variant shows poorer protein stability compared to wild-type and 29E4 variants. Constant-pH MD simulations revealed a more positively charged microenvironment near the heme pocket of variant 6E10, particularly in the neutral to alkaline pH range. This microenvironment affects enzyme activity by modulating the pK(a) of essential residues in the heme vicinity and should account for variant 6E10 improved activity at pH 7-8 compared to the wild-type and 29E4 that show optimal enzymatic activity close to pH 4. Our findings shed light on the structure-function relationships of DyPs at the molecular level, including their pH-dependent conformational plasticity. These are essential for understanding and engineering the catalytic properties of DyPs for future biotechnological applications. (c) 2022 The Author(s). Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology.
Autoantibodies against myelin oligodendrocyte glycoprotein in a subgroup of patients with psychotic symptoms
Publication . Burgt, Nikita A. van de; Kulsvehagen, Laila; Mané-Damas, Marina; Lutz, Luc; Lecourt, Anne-Catherine; Monserrat, Clara; Vinke, Anita M.; Küçükali, Cem İ.; Zong, Shenghua; Hoffmann, Carolin; González-Vioque, Emiliano; Arango, Celso; Leibold, Nicole K.; Losen, Mario; Molenaar, Peter C.; Tüzün, Erdem; Beveren, Nico J. M. van; Mané, Anna; Rouhl, Rob P. W.; Amelsvoort, Therese A. M. J. van; Pröbstel, Anne-Katrin; Martinez-Martinez, Pilar
The presence of autoantibodies against myelin oligodendrocyte glycoprotein (MOG) is a hallmark of MOG antibody-associated disease (MOGAD), a recently defined demyelinating disease entity presenting with core clinical features of optic neuritis, myelitis, and acute disseminated encephalomyelitis. Although MOG antibodies have also been described in a small number of patients with other conditions, including mental disorders, their prevalence and clinical specificity in patients with isolated psychotic symptoms remain unclear. Here, we screened sera from 262 patients with at least one psychotic episode and 166 control subjects for the presence of MOG antibodies of the immunoglobulin G (IgG) isotype with a live cell-based assay. Serum reactivity to additional antigens was assessed by immunohistochemistry. Four patients, representing 1.5% of the patient cohort, and one control individual, representing. 0.6% of the healthy control cohort, were seropositive for MOG-IgG antibodies. Of the four MOG-IgG seropositive patients, three experienced visual hallucinations. Overall, MOG antibodies were detected at a low frequency in patients with psychotic episodes. While we cannot exclude the possibility of false-positive results or seroconversion due to secondary myelin damage, the association with visual hallucinations in three out of four MOG-IgG seropositive patients may point toward an underlying autoimmune etiology.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDP/04612/2020