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Projeto de investigação
novo: “Mechanism of glycosylation orchestrated by ClGal-Tl and ST6GalNAc-l enzymes unveiled by NMR. Targeting glycan-binding proteins towards the rational development of novel cancer immunomodulation therapies
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Structure-Guided Approach for the Development of MUC1-Glycopeptide-Based Cancer Vaccines with Predictable Responses
Publication . Bermejo, Iris A.; Guerreiro, Ana; Eguskiza, Ander; Martínez-Sáez, Nuria; Lazaris, Foivos S.; Asín, Alicia; Somovilla, Víctor J.; Compañón, Ismael; Raju, Tom K.; Tadic, Srdan; Garrido, Pablo; García-Sanmartín , Josune; Mangini, Vincenzo; Grosso, Ana S.; Marcelo, Filipa; Avenoza, Alberto; Busto, Jesús H.; García-Martín, Fayna; Hurtado-Guerrero, Ramón; Peregrina, Jesús M.; Bernardes, Gonçalo J. L.; Martínez, Alfredo; Fiammengo, Roberto; Corzana, Francisco; UCIBIO - Applied Molecular Biosciences Unit; DQ - Departamento de Química; ACS - American Chemical Society
Mucin-1 (MUC1) glycopeptides are exceptional candidates for potential cancer vaccines. However, their autoantigenic nature often results in a weak immune response. To overcome this drawback, we carefully engineered synthetic antigens with precise chemical modifications. To be effective and stimulate an anti-MUC1 response, artificial antigens must mimic the conformational dynamics of natural antigens in solution and have an equivalent or higher binding affinity to anti-MUC1 antibodies than their natural counterparts. As a proof of concept, we have developed a glycopeptide that contains noncanonical amino acid (2S,3R)-3-hydroxynorvaline. The unnatural antigen fulfills these two properties and effectively mimics the threonine-derived antigen. On the one hand, conformational analysis in water shows that this surrogate explores a landscape similar to that of the natural variant. On the other hand, the presence of an additional methylene group in the side chain of this analog compared to the threonine residue enhances a CH/π interaction in the antigen/antibody complex. Despite an enthalpy-entropy balance, this synthetic glycopeptide has a binding affinity slightly higher than that of its natural counterpart. When conjugated with gold nanoparticles, the vaccine candidate stimulates the formation of specific anti-MUC1 IgG antibodies in mice and shows efficacy comparable to that of the natural derivative. The antibodies also exhibit cross-reactivity to selectively target, for example, human breast cancer cells. This investigation relied on numerous analytical (e.g., NMR spectroscopy and X-ray crystallography) and biophysical techniques and molecular dynamics simulations to characterize the antigen-antibody interactions. This workflow streamlines the synthetic process, saves time, and reduces the need for extensive, animal-intensive immunization procedures. These advances underscore the promise of structure-based rational design in the advance of cancer vaccine development.
Structural basis for the synthesis of the core 1 structure by C1GalT1
Publication . González-Ramírez, Andrés Manuel; Grosso, Ana Sofia; Yang, Zhang; Compañón, Ismael; Coelho, Helena; Narimatsu, Yoshiki; Clausen, Henrik; Marcelo, Filipa; Corzana, Francisco; Hurtado-Guerrero, Ramon; UCIBIO - Applied Molecular Biosciences Unit; DQ - Departamento de Química; Nature Portfolio
C1GalT1 is an essential inverting glycosyltransferase responsible for synthesizing the core 1 structure, a common precursor for mucin-type O-glycans found in many glycoproteins. To date, the structure of C1GalT1 and the details of substrate recognition and catalysis remain unknown. Through biophysical and cellular studies, including X-ray crystallography of C1GalT1 complexed to a glycopeptide, we report that C1GalT1 is an obligate GT-A fold dimer that follows a SN2 mechanism. The binding of the glycopeptides to the enzyme is mainly driven by the GalNAc moiety while the peptide sequence provides optimal kinetic and binding parameters. Interestingly, to achieve glycosylation, C1GalT1 recognizes a high-energy conformation of the α-GalNAc-Thr linkage, negligibly populated in solution. By imposing this 3D-arrangement on that fragment, characteristic of α-GalNAc-Ser peptides, C1GalT1 ensures broad glycosylation of both acceptor substrates. These findings illustrate a structural and mechanistic blueprint to explain glycosylation of multiple acceptor substrates, extending the repertoire of mechanisms adopted by glycosyltransferases.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
SFRH/BD/140394/2018