Biology subjects

Marchetti, R.

Publications and source records attributed to Marchetti, R..

3 recordsLinked to original sources

bioRxiv2026

GLYCAM Bacterial Carbohydrate Builder: a web-tool for modelling 3D structures of bacterial glycans

Here we present the GLYCAM Bacterial Carbohydrate Builder (https://glycam.org/cb), an enhanced version of the GLYCAM-Web Carbohydrate Builder1 structure modeller that integrates support for modelling bacterial glycans, enabling the straightforward generation of three-dimensional structural models. The tool integrates bacterial monosaccharide parametrisations into a curated, user-friendly web-based resource. It provides an intuitive interface for the generation of carbohydrate sequences and generates 3D structural models in PDB file format, as well as the input files required for performing molecular dynamics simulations with the AMBER software package. The current implementation includes a library of 18 bacterial monosaccharides, which can be used in combination with the already parametrised eukaryotic sugars to construct complex bacterial glycans. Common derivatives, including acetylation, methylation, and sulfation are also supported. By validating and integrating bacterial sugar parameters into the GLYCAM-Web Carbohydrate Builder, this work reduces the technical barriers associated with bacterial glycan modelling and facilitates computational studies of complex bacterial glycoconjugates.

bioinformatics↗

bioRxiv2025

Lipopolysaccharides nanodiscs, a biomimetic platform to study bacterial surface.

Lipopolysaccharides (LPS) are essential components of the outer membranes of Gram-negative bacteria, playing a crucial role in antimicrobial resistance, virulence, and the hosts immune response. Self-assembled particles displaying LPS are essential for biophysical studies addressing the behavior of bacterial surfaces under specific biomimetic conditions. Styrene-maleic acid (SMA) copolymers were employed to form LPS nanodiscs, either from extracted LPS or directly from purified outer membranes. These nanodiscs, derived from pathogenic O157:H7 or laboratory E. coli strains, are well-defined in size and yield high-resolution nuclear magnetic resonance (NMR) spectra. They have been successfully used to investigate molecular recognition by a human C-type Lectin Receptor (CLR) of the immune system and interaction with polymyxin antibiotics using various biophysical methods. This study high-lights the significance of LPS nanodiscs as bacterial surface mimetics and opens promising avenues for further research into LPS structure and interactions. The ability to generate well-defined LPS nanodiscs offers a powerful tool for studying the molecular mechanisms underlying bacterial pathogenesis and immune response.

biophysics↗

bioRxiv2023

The unique three-dimensional arrangement of Macrophage Galactose Lectin enables E. coli LipoPolySaccharides recognition through two distinct interfaces

LipoPolySaccharides are a hallmark of Gram-negative bacteria and their presence at the cell surface is key for bacterial integrity. As surface exposed components, they are recognized by immunity C-type lectin receptors present on Antigen Presenting Cells. Human Macrophage Galactose Lectin binds E. coli surface that presents a specific glycan motif. Nevertheless, this high affinity interaction occurs regardless of the integrity of its canonical calcium-dependent glycan binding site. Nuclear Magnetic Resonance of MGL carbohydrate recognition domain and complete extracellular domain revealed a new glycan binding site opposite to the canonical site. A model of trimeric Macrophage Galactose Lectin was determined based on a combination of Small Angle X-ray scattering and Alphafold. A disulphide bond positions the Carbohydrate Recognition Domain perpendicular to the coiled-coil domain. This unique configuration for a C-type lectin orients the six glycan sites of MGL in an ideal position to bind LipoPolySaccharides at the bacterial surface with high avidity.

biophysics↗