Biology subjects

Squeglia, F.

Publications and source records attributed to Squeglia, F..

3 recordsLinked to original sources

bioRxiv2025

DepoCatalog: Mapping the Diversity of 105 Recombinant Klebsiella Phage Depolymerases Across Sequence, Structure, and Substrate Specificity

A validated catalog of 105 recombinant depolymerases from Klebsiella phages covers 58 KL-types. 46 novel enzymes from prophages, jumbo phages, and common phages are linked to any known enzymatic activity against 14 classical serotypes and 12 genome-defined KL-types. Using activity-based profiling, structure prediction, and domain dissection, we developed a function-guided classification and a five-class structural catalog. This framework reveals highly specific enzymes active against up to three capsule types. K47 CPS was degraded by three diverse protein groups. Structurally similar depolymerases degrading particular CPS were found in distinct phage taxa, with highly conserved enzymes in Drulisvirus specific to K1-, K2-types. The exclusive depolymerases were found in siphoviruses targeting K2 and K62 serotypes. A case study of five structurally similar enzymes degrading KL22/KL37/KL111 and KL25/KL119 capsules suggested specificity switching via amino acid changes or C-domain modification. Klebsiella phage depolymerases catalog sheds light on their diversity, evolution, and potential application.

microbiology↗

bioRxiv2025

A self-assembling cross-protective antigen against multiple Gram-positive nosocomial pathogens

ESKAPE pathogens are responsible for complicated nosocomial infections worldwide and are usually resistant to commonly used antibiotics in clinical settings. Among these bacteria, vancomycin-resistant Enterococcus faecium and methicillin-resistant Staphylococcus aureus are the two most important Gram-positive pathogens for which alternative treatments and preventions are urgently needed. We previously designed a multi-presenting antigen, embedding the main epitope displayed by the AdcA protein of E. faecium, that conferred protection against different Gram- positive pathogens both in passive and active immunization models. Here, we developed a new presentation strategy for this epitope, the EH-motif, based on a self-assembling peptide. Self- assembling peptides have been promising in the fields of material sciences, nanoscience, and medicine and have also potential in vaccine development, as they allow multiple presentations of the epitope and provide an ideal size for production and application. We show that this multi- presenting peptide, here Q11-EH, forms stable fibers of nanometric size. We also demonstrate that antibodies raised against Q11-EH mediate the opsonic killing of a wide-spectrum of Gram-positive pathogens, including E. faecium, S. aureus, and E. faecalis. Our data indicate that multiple presentation strategies are a potent tool for vaccine antigen improvement and point to Q11-EH as a promising antigen for the development of novel cross-protective vaccines.

immunology↗

bioRxiv2020

An engineered stable mini-protein to plug SARS-Cov2 Spikes

AO_SCPLOWBSTRACTC_SCPLOWThe novel betacoronavirus SARS-CoV-2 is the etiological agent of the current pandemic COVID-19. Like other coronaviruses, this novel virus relies on the surface Spike glycoprotein to access the host cells, mainly through the interaction of its Receptor Binding Domain (RBD) with the human angiotensin-converting enzyme 2 (ACE2). Therefore, molecular entities able to interfere with binding of the SARS-CoV-2 Spike protein to ACE2 have a great potential to inhibit viral entry. Starting from the available structural data on the interaction between SARS-CoV-2 Spike protein and the host ACE2 receptor, we here engineered a mini-protein with the aim of creating a soluble and stable Spike interactor. This mini-protein, which was recombinantly produced in high yields, possesses a stable helical conformation and is able to interact with the RBD of glycosylated Spike protein from SARS-CoV-2 with nanomolar affinity, as measured by microscale thermophoresis. By plugging the Spike protein, our mini-protein constitutes a valid tool for the development of treatments against different types of coronavirus.

biophysics↗