Marta G Lete

Center for Cooperative Research in Biosciences | CIC bioGUNE · Structural Biology Unit

Glycan‐mediated molecular recognition events are essential for life. NMR is widely used to monitor glycan binding to lectins in solution using isolated glycans and lectins. In this context, we herein explore diverse NMR methodologies, from both the receptor and ligand perspectives, to monitor glycan‐lectin interactions under experimental conditions...

Lectin-glycan interactions are at the heart of a multitude of biological events. Glycans are usually presented in a multivalent manner on the cell surface as part of the so-called glycocalyx, where they interact with other entities. This multivalent presentation allows us to overcome the typical low affinities found for individual glycan-lectin int...

Fluorine (¹⁹F) incorporation into glycan‐binding proteins (lectins) has been achieved and exploited to monitor the binding to carbohydrate ligands by nuclear magnetic resonance (NMR) spectroscopy. Galectins are a family of lectins that bind carbohydrates, generally with weak affinities, through a combination of intermolecular interactions including...

We herein report the first total synthesis of the Streptococcus pneumoniae serotype 1 (Sp1) oligosaccharide, a unique zwitterionic capsular polysaccharide carrying labile O‐acetyl esters. The target oligosaccharides, featuring rare α‐2,4‐diamino‐2,4,6‐trideoxy galactose (AAT) and α‐galacturonic acids, were assembled up to the 9‐mer level, in a high...

We herein report the first total synthesis of the Streptococcus pneumoniae serotype 1 (Sp1) oligosaccharide, a unique zwitterionic capsular polysaccharide carrying labile O‐acetyl esters. The target oligosaccharides, featuring rare α‐2,4‐diamino‐2,4,6‐trideoxy galactose (AAT) and α‐galacturonic acids, were assembled up to the 9‐mer level, in a high...

Galectins are a family of glycan binding proteins that stand out for the wide range of biological phenomena in which they are involved. Most galectin functions are associated with their glycan binding capacities, which are generally well characterized at the oligosaccharide level, but not at the glycoprotein or glycolipid level. Glycolipids form th...

The use of MW allows the efficient palladium(II)-catalysed C-3 acylation of thiophenes with aldehydes via C(sp2)-H activation for the synthesis of (cyclo)alkyl/aryl thienyl ketones (43 examples). Compared to standard thermal conditions, the use of MW reduces the reaction time (15 to 30 min vs. 1 to 3 hours), leading to improved yields of the ketone...

Highly substituted coumarins, privileged and versatile scaffolds for bioactive natural products and fluorescence imaging, are obtained via a Pd(II)-catalyzed direct C–H alkenylation reaction (Fujiwara–Moritani reaction), which has emerged as a powerful tool for the construction and functionalization of heterocyclic compounds because of its chemical...

The interaction of multi-LacNAc (Galβ1-4GlcNAc)-containing N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers with human galectin-1 (Gal-1) and the carbohydrate recognition domain (CRD) of human galectin-3 (Gal-3) was analyzed using NMR methods in addition to cryo-electron-microscopy and dynamic light scattering (DLS) experiments. The interaction...

This chapter is dedicated to the presentation of different examples of the application of solution NMR to the study of conformation, dynamics of sugar molecules (oligo and polysaccharides, glycopeptides and glycomimetics) including the investigation of glycan-related molecular recognition events. It is not our intention to be exhaustive, rather to...

Cellular membranes are critical platforms for intracellular signaling that involve complex interfaces between lipids and proteins, and a web of interactions between a multitude of lipid metabolic pathways. Membrane lipids impart structural and functional information in this regulatory circuit that encompass biophysical parameters such as membrane t...

Phosphatidylinositol-transfer proteins (PITPs) are key regulators of lipid signaling in eukaryotic cells. These proteins both potentiate the activities of phosphatidylinositol (PtdIns) 4-OH kinases and help channel production of specific pools of PtdIns-4-phosphate (PtdIns4P) dedicated to specific biological outcomes. In this manner, PITPs represen...

Detergents are water-soluble amphiphiles. Above a critical concentration they self-organize in micelles and in the presence of phospholipids mixed micelles are formed. Much information is available on the structure of these self-assemblies and on the thermodynamics of their formation. The aim of this study was to deepen our understanding of the mec...

Recent years have witnessed the evolution of the cell biology of lipids into an extremely active area of investigation. Deciphering the involvement of lipid metabolism and lipid signaling in membrane trafficking pathways defines a major nexus of contemporary experimental activity on this front. Significant effort in that direction is invested in un...

In mammals, the START‐like phosphatidylinositol transfer proteins (PITPs) remain an understudied group of proteins implicated in human health and disease. Phosphatidylinositol transfer protein alpha (PITPa) is linked to human epidermal growth factor receptor (HER2)‐positive metastatic breast cancer drug resistance, and muscular dystrophy, but its p...

Despite current dogma stating that phosphatidylinositol transfer protein a (PITPa) is required for growth factor signaling, little evidence has emerged supporting these claims. Data from our laboratory, gathered from multiple experimental systems, strongly dispute the current doctrine and indicate that in contrast to previous reports PITPa is dispe...

Biogenic polyamines (PAs), spermine, spermidine and putrescine are widely spread amino acid derivatives, present in living cells throughout the whole evolutionary scale. Their amino groups confer them a marked basic character at the cellular pH. We have tested the interaction of PAs with negatively-charged phospholipids in the absence and presence...

In recent years, phosphatidylinositol (PtdIns) transfer proteins (PITPs) have been established as essential regulators of phosphoinositide signaling outcomes in eukaryotic cells. The key function of these proteins is to mediate a PtdIns/phosphatidylcholine (PtdCho) exchange reaction. This function is central to their abilities to regulate lipid sig...

The nuclear envelope (NE) needs to be reassembled after each mitotic cycle and also after fertilization, it is important to understand the regulation and dynamics of this universally conserved membrane fusion phenomenon. In this work we report the requirement of Class I PI3-Kinases for the NE formation in vitro, and its involvement in the fusion of...

Regulation of nuclear envelope (NE) dynamics is an important example of the universal phenomena of membrane fusion. The signalling molecules involved in nuclear membrane fusion may also be conserved in the formation of both pronuclear and zygote NEs in the fertilised egg. Here, we determine that Class I PI3-kinases are needed for in vitro nuclear e...

Recently the presence of phosphoinositides (PIPns) in the eukaryotic cell nucleoplasm and nuclear membrane has been described (1). We have studied the interaction of the nuclear proteins, histones, with these lipids in model membranes. Turbidimetric studies revealed that histones induce extensive aggregation of vesicles when containing phosphatidyl...

We have studied the effect of adding lipid nanovesicles (liposomes) on the aggregation of commercial titanium oxide (TiO2), zinc oxide (ZnO), or cerium oxide (CeO2) nanoparticles (NPs) suspensions in Hepes buffer. Liposomes were prepared with pure phospholipids or mixtures of phospholipids and/or cholesterol. Changes in turbidity were recorded as a...

PKB/Akt activation is a common step in tumourigenesis, proliferation, and survival. Akt activation is understood to occur at the plasma membrane of cells in response to growth factor stimulation and local production of the phosphoinositide lipid PtdIns(3,4,5)P3 following phosphoinositide 3-kinase (PI3K) activation. The metabolism and turnover of ph...

Polarized membrane morphogenesis is a fundamental activity of eukaryotic cells. This process is essential for the biology of cells and tissues, and its execution demands exquisite temporal coordination of functionally diverse membrane signaling reactions with high spatial resolution. Moreover, mechanisms must exist to establish, and preserve, such...

In a previous article, we demonstrated that histones (H1 or histone octamers) interact with negatively charged bilayers and induce extensive aggregation of vesicles containing phosphatidylinositol-4-phosphate (PIP) and, to a lesser extent, vesicles containing phosphatidylinositol (PI). Here, we found that vesicles containing PIP, but not those cont...

Recent discoveries on the presence and location of phosphoinositides in the eukaryotic cell nucleoplasm and nuclear membrane prompted us to study the putative interaction of chromatin components with these lipids in model membranes (liposomes). Turbidimetric studies revealed that a variety of histones and histone combinations (H1, H2AH2B, H3H4, oct...