Biology subjects

D'Alessio, C.

Publications and source records attributed to D'Alessio, C..

3 recordsLinked to original sources

bioRxiv2025

Production of high-affinity glycosylated anti-mouse conjugated nanobodies in Pichia pastoris

Nanobodies (NBs) are small antibody fragments derived from camelid heavy-chain antibodies which represent the minimal functional domain capable of antigen recognition and binding. NB are ten times smaller than conventional antibodies, exhibit a compact structure and high stability, making them ideal for recombinant production. The eukaryotic unicellular system Pichia pastoris provides multiple advantages for protein expression, including the ability to perform several eukaryotic posttranslational modifications. In this work, we engineered a modular plasmid sequence that, through specific restriction enzyme cuts and ligations, codes the expression of a secreted anti-mouse kappa chain NB fused with various accessory peptides in P. pastoris. This system enables the incorporation of a plastic binding sequence, a histidine tag (Hisx6) for purification, the horseradish peroxidase (HRP) enzyme for chemiluminescence detection, or the biotinylatable AviTag sequence, in multiple combinations. We successfully expressed and purified anti-kappa NBs fused to a Hisx6-tag ({kappa}NB) and to HRP -Hisx6-tag ({kappa}NB-HRP), with subsequent structural and functional characterization revealing high affinity for mouse immunoglobulins. The {kappa}NB-kappa light chain domain complex was modeled showing a fitted surface interaction of CDR3 domain. The position of a glycan in the complex was modeled predicting that glycan addition would not affect the interaction surface. Accordingly, no functional differences were observed in {kappa}NB after deglycosylation, indicating that high mannose glycan addition has not interfered with its binding capability. Moreover, glycosylated {kappa}NB fused to HRP was expressed with retained HRP activity, and proved to be functional as a secondary antibody, demonstrating the systems versatility in producing NBs and conjugated NBs with posttraslational modification that may be required for diverse biotechnological applications.

molecular biology↗

bioRxiv2021

Production of a Highly Immunogenic Antigen from SARS-CoV-2 by Covalent Coupling of the Receptor Binding Domain of Spike Protein to a Multimeric Carrier

Since the discovery of SARS-CoV-2, several antigens have been proposed to be part of COVID-19 vaccines. The receptor binding domain (RBD) of Spike protein is one of the promising candidates to develop effective vaccines since it can induce potent neutralizing antibodies. We previously reported the production of RBD in Pichia pastoris and showed it is structurally identical to the protein produced in mammalian HEK-293T cells. In this work we designed an RBD multimer construct with the purpose of increasing RBD immunogenicity. We produced multimeric particles by a transpeptidation reaction between the RBD expressed in P. pastoris and Lumazine Synthase from Brucella abortus (BLS), which is a highly immunogenic and very stable decameric protein of 170 kDa. We vaccinated mice with two doses 30 days apart, and then we measured humoral immune response. When the number of RBD copies coupled to BLS was high (6-7 RBD molecules per BLS decamer, in average), the immune response was significantly better than that elicited by RBD alone or even by RBD-BLS comprising low number of RBD copies (1-2 RBD molecules per BLS decamer). Remarkably, the construct with high number of RBD copies induced high IgG titers with high neutralizing capacity. Furthermore, a superior immune response was observed when Al(OH)3 adjuvant was added to this formulation, exhibiting a higher titer of neutralizing antibodies. Altogether our results suggest that RBD covalent coupled to BLS forming a multimer-particle shows an advantageous architecture to the antigen-presentation to the immune system which enhances immune responses. This new antigen should be considered a potent candidate for a protein-based vaccine.

biochemistry↗

bioRxiv2020

Structural and Functional Comparison of SARS-CoV-2-Spike Receptor Binding Domain Produced in Pichia pastoris and Mammalian Cells

The yeast Pichia pastoris is a cost-effective and easily scalable system for recombinant protein production. In this work we compared the conformation of the receptor binding domain (RBD) from SARS-CoV-2 Spike protein expressed in P. pastoris and in the well established HEK-293T mammalian cell system. RBD obtained from both yeast and mammalian cells was properly folded, as indicated by UV-absorption, circular dichroism and tryptophan fluorescence. They also had similar stability, as indicated by temperature-induced unfolding (observed Tm were 50 {degrees}C and 52 {degrees}C for RBD produced in P. pastoris and HEK-293T cells, respectively). Moreover, the stability of both variants was similarly reduced when the ionic strength was increased, in agreement with a computational analysis predicting that a set of ionic interactions may stabilize RBD structure. Further characterization by HPLC, size-exclusion chromatography and mass spectrometry revealed a higher heterogeneity of RBD expressed in P. pastoris relative to that produced in HEK-293T cells, which disappeared after enzymatic removal of glycans. The production of RBD in P. pastoris was scaled-up in a bioreactor, with yields above 45 mg/L of 90% pure protein, thus potentially allowing large scale immunizations to produce neutralizing antibodies, as well as the large scale production of serological tests for SARS-CoV-2.

biochemistry↗