Biology subjects

Malchiodi, E. L.

Publications and source records attributed to Malchiodi, E. L..

4 recordsLinked to original sources

bioRxiv2025

Development of novel high-affinity nanobodies against EGFR for cancer therapy

The epidermal growth factor receptor (EGFR) is a member of a family of transmembrane tyrosine kinase receptors that plays a pivotal role in regulating diverse cellular processes such as cell proliferation, survival, migration, and differentiation. Aberrant activation of EGFR signaling has been implicated in various pathological conditions, particularly cancer, making it an attractive target for therapeutic intervention. While several anti-EGFR monoclonal antibodies have been developed and demonstrated their clinical value for the treatment of various solid tumors, smaller antibody fragments such as nanobodies (Nb) offer distinct advantages over conventional antibodies, including reduced immunogenicity and enhanced tumor penetration. In this paper, we report the isolation and characterization of two novel high-affinity Nb targeting EGFR. These Nb were identified and characterized using ELISA, flow cytometry, microscopy, and SPR. Furthermore, these Nb and bivalent Nb engineered from them were tested for their effects on cancer cell proliferation. We demonstrate that the novel Nb exhibit high affinity and potent anti-tumor activity in vitro in their bivalent form, positioning them as promising candidates for cancer treatment.

molecular biology↗

bioRxiv2024

High-fat and high-carbohydrate diets worsen the mouse brain susceptibility to damage produced by enterohemorrhagic Escherichia coli Shiga toxin 2

BackgroundNutrition quality could be one of the reasons why, in the face of a Shiga toxin-producing enterohaemorrhagic Escherichia coli outbreak, some patients experience more profound deleterious effects than others, including unfortunate deaths. Thus, the aim of this study was to determine whether high-fat and/or high-carbohydrate diets could negatively modulate the deleterious action of Shiga toxin 2 on ventral anterior and ventral lateral thalamic nuclei and the internal capsule, the neurological centers responsible for motor activity. MethodsMice were fed a regular, high-fat, high-carbohydrate diet or a combination of both previous to the intravenous administration of Shiga toxin 2 or vehicle. Four days after intravenous administration, mice were subjected to behavioral tests and then sacrificed for histological and immunofluorescence assays to determine alterations in the neurovascular unit at the cellular and functional levels. Statistical analysis was performed using one-way analysis of variance followed by Bonferroni post hoc test. The criterion for significance was p = 0.0001 for all experiments. ResultsThe high-fat and the high-carbohydrate diets significantly heightened the deleterious effect of Stx2, while the combination of both diets yielded the worst results, including endothelial glycocalyx and oligodendrocyte alterations, astrocyte and microglial reactivity, neurodegeneration, and motor and sensitivity impairment. ConclusionsIn view of the results presented here, poor nutrition could negatively influence patients affected by Stx2 at a neurological level. Systemic effects, however, cannot be ruled out.

microbiology↗

bioRxiv2020

New insights into how MutS separates its function in the regulation of the Pol IV access to replication sites from that in the conserved MMR pathway

MutS initiates mismatch repair by recognizing mismatches in newly replicated DNA. Specific interactions between MutS and mismatches within double-stranded DNA promote ADP-ATP exchange and a conformational change into a sliding clamp. Here, we demonstrated that MutS from Pseudomonas aeruginosa associates with primed DNA replication substrates. The predicted structure of this MutS-DNA complex revealed a new DNA binding site, in which Asn 279 and Arg 272 appeared to directly interact with the 3-OH terminus of primed DNA. Mutation of these residues resulted in a noticeable defect in the interaction of MutS with replication DNA substrates. Remarkably, MutS interaction with a mismatch within primed DNA induced a compaction of the protein structure and impaired the formation of an ATP-bound sliding clamp. Our findings reveal a novel DNA binding mode, conformational change and intramolecular signaling for MutS recognition of mismatches within DNA replication structures.

biochemistry↗

bioRxiv2020

Mycobacterium tuberculosis FasR senses long fatty acyl-CoA through a tunnel, inducing DNA-dissociation via a transmission spine

Mycobacterium tuberculosis is a pathogen with a unique cell envelope including very long fatty acids, implicated in bacterial resistance and host immune modulation. FasR is a two-domain transcriptional activator that belongs to the TetR family of regulators, and plays a central role in mycobacterial long-chain fatty acyl-CoA sensing and lipid biosynthesis regulation. We now disclose crystal structures of M. tuberculosis FasR in complex with acyl effector ligands and with DNA, uncovering its sensory and switching mechanisms. A long tunnel traverses the entire effector-binding domain, enabling long fatty acyl effectors to bind. Only when the tunnel is entirely occupied, the protein dimer adopts a rigid configuration, with its DNA-binding domains in an open state that leads to DNA dissociation. Structure-guided point-mutations further support this effector-dependent mechanism. The protein-folding hydrophobic core, connecting the two domains, is completed by the effector ligand into a continuous spine, explaining the allosteric flexible-to-ordered transition. The transmission spine is conserved in all TetR-like transcription factors, offering new opportunities for anti-tuberculosis drug discovery.

microbiology↗