Antimicrobial resistance (AMR) represents a major threat to global public health in the 21st century, dramatically increasing the pandemic expectations in the coming years. The ongoing need to develop new antimicrobial treatments that are effective against multi-drug-resistant pathogens has led the research community to investigate innovative strategies to tackle AMR. The bacterial cell envelope has been identified as one of the key molecular players responsible for antibiotic resistance, attracting considerable interest as a potential target for novel antimicrobials effective against AMR, to be used alone or in combination with other drugs. However, the multicomponent complexity of bacterial membranes provides a heterogeneous morphology, which is typically difficult to study at the molecular level by experimental techniques, in spite of the significant development of fast and efficient experimental protocols. In recent years, computational modeling, in particular, molecular dynamics simulations, has proven to be an effective tool to reveal key aspects in the architecture and membrane organization of bacterial cell walls. Here, after a general overview about bacterial membranes, AMR mechanisms, and experimental approaches to study AMR, we review the state-of-the-art computational approaches to investigate bacterial AMR envelopes, including their limitations and challenges ahead. Representative examples illustrate how these techniques improve our understanding of bacterial membrane resistance mechanisms, hopefully leading to the development of novel antimicrobial drugs escaping from bacterial resistance strategies.

Carbohydrate-lectin interactions intervene in and mediate most biological processes, including ac rucial modulation of immune responsest op athogens. Despite growing interesti n investigating the association between host receptorl ectins and exogenous glycanl igands, the molecular mechanisms underlying bacterial recognition by human lectins are still not fully understood.H erein, an ovel molecular interaction between the human macrophage galactose-type lectin (MGL) and the lipooligosaccharide (LOS) of Escherichia coli strain R1 is described. Saturation transfer difference NMR spectroscopy analysis, supportedb yc omputational studies, demonstrated that MGL bound to the purified deacylated LOS R1 mainly throughr ecognition of its outer core and established crucial interactions with the terminal Gala(1,2)Gal epitope. These results assess the ability of MGL to recognise glycan moieties exposed on Gram-negative bacterial surfaces.Bacterialc ell surfaces are decorated with highly diverseg lycoconjugates,i nt he form of capsular polysaccharides, peptidoglycans, lipopolysaccharides( LPSs) and other glycolipids, [1] which perform severalf unctions, ranging from structural to protective roles. [2] Bacterial glycans take part in many keyb iological events, including pathogen recognition,receptor activation, cell adhesion and signal transduction. Additionally,t hese structures often serve as molecular patterns that are recognised by specific glycan-binding receptors of the host immune system,t hus triggeringapathogen-specific immune response.It is well known that LPSs, the major constituents of the outer membrane of Gram-negative bacteria, [3] are one of the main virulence factorsofseveral feared bacterialstrains,including enteropathogenic Escherichia coli,w hich is implicated in severe foodborne and urinary tract infections. [4] From as tructural point of view,L PS is composed of three structural motifs that can be distinguishedb ecause they are encoded by different gene clusters. Lipid A, which represents the glycolipid portion, is an acylated bis-phosphorylated glucosamined isaccharide that anchors the LPS to the outer membrane. Lipid Ai sc ovalentlyl inked to ac ore oligosaccharide (OS) that can be further divided into two different portions: the more conserved inner region, which is characterised by the presence of peculiar sugar residues,s uch as 3-deoxy-d-manno-oct-2-ulopyranosonic acid (KDO),a nd the more variableo uter core. Finally,t he O-antigen, which is ap olysaccharide composed of severalO S repeating units, extends to the extracellularm edium and acts as ah ydrophilic coating surface. [3,5] However,G ram-negative bacteria can also produce rough-typeL PS, namely,l ipooligosaccharide (LOS);atruncated version of LPS that lacks the Oantigen.To date, the receptor complex formed by the toll-like receptor 4a nd the small secreted MD2 protein is among the main speciesi nvolved in bacterial LPS recognition by host immune cells. [6] More recently,i th as been shown that LPSs are also intracellularly detected by caspases...

HIGHLIGHTSWe unveiled the molecular basis of sialoglycans recognition by Siglec-10The conformation of sialoglycans drives the interaction with the protein Siglec-10 is able to recognize and bind complex N-glycansOur outcomes may open the venue for the design and development of novel glycomimetics

CD22 (Siglec‐2) is a B‐cell surface inhibitory protein capable of selectively recognising sialylated glycans, thus dampening autoimmune responses against self‐antigens. Here we have characterised the dynamic recognition of complex‐type N‐glycans by human CD22 by means of orthogonal approaches including NMR spectroscopy, computational methods and biophysical assays. We provide new molecular insights into the binding mode of sialoglycans in complex with h‐CD22, highlighting the role of the sialic acid galactose moieties in the recognition process, elucidating the conformational behaviour of complex‐type N‐glycans bound to Siglec‐2 and dissecting the formation of CD22 homo‐oligomers on the B‐cell surface. Our results could enable the development of additional therapeutics capable of modulating the activity of h‐CD22 in autoimmune diseases and malignancies derived from B‐cells.