Chemo-enzymatic synthesis of NPN cofactor taking advantage of ADP-ribosyl cyclase and LarC cyclometallase promiscuous activities.

The nickel-pincer nucleotide cofactor (NPN) is a widespread organometallic cofactor required for lactate racemase (LarA) and for α-hydroxy acid racemases and epimerases of the LarA superfamily. Its biosynthesis, which starts with nicotinic acid adenine dinucleotide (NaAD), requires three enzymes: LarB, LarC, and LarE, and can be performed in vitro with purified enzymes. Nevertheless, as LarE and LarC are single turnover enzymes, the in vitro NPN biosynthesis requires huge amounts of enzymes (particularly 2 equivalents of LarE), which hampers the study of NPN and of NPN-dependent enzymes.

RNA polymerase II transcription initiation in holo-TFIID-depleted mouse embryonic stem cells.

The recognition of core promoter sequences by TFIID is the first step in RNA polymerase II (Pol II) transcription initiation. Metazoan holo-TFIID is a trilobular complex, composed of the TATA binding protein (TBP) and 13 TBP-associated factors (TAFs). Why and how TAFs are necessary for the formation of TFIID domains and how they contribute to transcription initiation remain unclear.

Exploring fluorinated heptose phosphate analogues as inhibitors of HldA and HldE, key enzymes in the biosynthesis of lipopolysaccharide.

The growing threat of bacterial resistance to antibiotics has led to the rise of anti-virulence strategies as a promising approach. These strategies aim to disarm bacterial pathogens and improve their clearance by the host immune system. Lipopolysaccharide, a key virulence factor in Gram-negative bacteria, has been identified as a potential target for anti-virulence agents.

De novo variants in ATXN7L3 lead to developmental delay, hypotonia and distinctive facial features.

Deubiquitination is crucial for the proper functioning of numerous biological pathways, such as DNA repair, cell cycle progression, transcription, signal transduction and autophagy. Accordingly, pathogenic variants in deubiquitinating enzymes (DUBs) have been implicated in neurodevelopmental disorders and congenital abnormalities. ATXN7L3 is a component of the DUB module of the Spt-Ada-Gcn5 acetyltransferase (SAGA) complex and two other related DUB modules, and it serves as an obligate adaptor protein of three ubiquitin-specific proteases (USP22, USP27X or USP51).

Thioarylation of 6-Amino-2,3,6-trideoxy-d-manno-oct-2-ulosonic Acid (IminoKdo): Access to 3,6-Disubstituted Picolinates and Mechanistic Insights.

In this work, we present a metal-free coupling protocol for the regio- and stereoselective C3-thioarylation of 6-amino-2,3,6-trideoxy-d-manno-oct-2-ulosonic acid (iminoKdo). The developed procedure enables the coupling of electron-rich, electron-deficient, and hindered arylthiols, providing a series of C3-modified iminoKdo derivatives in moderate to good yields. Elucidation of active species through controlled experimental studies and time-lapse P NMR analysis provides insights into the reaction mechanism.

RNA polymerase II transcription with partially assembled TFIID complexes.

The recognition of core promoter sequences by the general transcription factor TFIID is the first step in the process of RNA polymerase II (Pol II) transcription initiation. Metazoan holo-TFIID is composed of the TATA binding protein (TBP) and of 13 TBP associated factors (TAFs). Inducible knock out (KO) results in the formation of a Taf7-less TFIID complex, while KO leads to serious defects within the TFIID assembly pathway.

Proton- versus Cation-Selective Transport of Saccharide Rim-Appended Pillar[5]arene Artificial Water Channels.

Transport of water across cell membranes is a fundamental process for important biological functions. Herein, we focused our research on a new type of symmetrical saccharide rim-functionalized pillar[5]arene (PA-S) artificial water channels with variable pore structures. To point out the versatility of PA-S channels, we systematically varied the nature of anchoring/gate keepers d-mannoside, d-mannuronic acid, or sialic acid H-bonding groups on lateral pillar[5]arene (PA) arms, known as good membrane adhesives, to best describe the influence of the chemical structure on their transport activity.

ATAC and SAGA co-activator complexes utilize co-translational assembly, but their cellular localization properties and functions are distinct.

To understand the function of multisubunit complexes, it is of key importance to uncover the precise mechanisms that guide their assembly. Nascent proteins can find and bind their interaction partners during their translation, leading to co-translational assembly. Here, we demonstrate that the core modules of ATAC (ADA-two-A-containing) and SAGA (Spt-Ada-Gcn5-acetyltransferase), two lysine acetyl transferase-containing transcription co-activator complexes, assemble co-translationally in the cytoplasm of mammalian cells.

ATAC and SAGA coactivator complexes utilize co-translational assembly, but their cellular localization properties and functions are distinct.

To understand the function of multisubunit complexes it is of key importance to uncover the precise mechanisms that guide their assembly. Nascent proteins can find and bind their interaction partners during their translation, leading to co-translational assembly. Here we demonstrate that the core modules of ATAC (ADA-Two-A-Containing) and SAGA (Spt-Ada-Gcn5-acetyltransferase), two lysine acetyl transferase-containing transcription coactivator complexes, assemble co-translationally in the cytoplasm of mammalian cells.

Glycofullerene-AuNPs as multivalent ligands of DC-SIGN and bacterial lectin FimH: tuning nanoparticle size and ligand density.

Glycoclusters have been extensively investigated for their inhibition of multivalent carbohydrate-protein interactions, which is often the first step for bacterial and viral pathogens to selectively bind their host cells. Glycoclusters may thus prevent infections by blocking the microbe attachment onto the host cell surface. The potency of multivalent carbohydrate-protein interactions is largely derived from the spatial arrangement of the ligand and the nature and flexibility of the linker.

Lipopolysaccharide biosynthesis and traffic in the envelope of the pathogen Brucella abortus.

Lipopolysaccharide is essential for most Gram-negative bacteria as it is a main component of the outer membrane. In the pathogen Brucella abortus, smooth lipopolysaccharide containing the O-antigen is required for virulence. Being part of the Rhizobiales, Brucella spp.

Evaluation of Azido 3-Deoxy-d--oct-2-ulosonic Acid (Kdo) Analogues for Click Chemistry-Mediated Metabolic Labeling of DZ2 Lipopolysaccharide.

Metabolic labeling paired with click chemistry is a powerful approach for selectively imaging the surfaces of diverse bacteria. Herein, we explored the feasibility of labeling the lipopolysaccharide (LPS) of -a Gram-negative predatory social bacterium known to display complex outer membrane (OM) dynamics-via growth in the presence of distinct azido (-N) analogues of 3-deoxy-d--oct-2-ulosonic acid (Kdo). Determination of the LPS carbohydrate structure from strain DZ2 revealed the presence of one Kdo sugar in the core oligosaccharide, modified with phosphoethanolamine.

SUPT3H-less SAGA coactivator can assemble and function without significantly perturbing RNA polymerase II transcription in mammalian cells.

Coactivator complexes regulate chromatin accessibility and transcription. SAGA (Spt-Ada-Gcn5 Acetyltransferase) is an evolutionary conserved coactivator complex. The core module scaffolds the entire SAGA complex and adopts a histone octamer-like structure, which consists of six histone-fold domain (HFD)-containing proteins forming three histone-fold (HF) pairs, to which the double HFD-containing SUPT3H adds one HF pair.

SAGA-Dependent Histone H2Bub1 Deubiquitination Is Essential for Cellular Ubiquitin Balance during Embryonic Development.

Ubiquitin (ub) is a small, highly conserved protein widely expressed in eukaryotic cells. Ubiquitination is a post-translational modification catalyzed by enzymes that activate, conjugate, and ligate ub to proteins. Substrates can be modified either by addition of a single ubiquitin molecule (monoubiquitination), or by conjugation of several ubs (polyubiquitination).

Synthesis of Spirocyclic Cyclopropyl Glycosyl-1-phosphate Analogues.

A general methodology allowing the preparation of phosphonylated 1-spirocyclopropyl analogues of glycosyl-1-phosphates is reported. The scope of this reaction has been assessed using various -glycals easily obtained from the corresponding pyranoses and furanoses. The cyclopropanation was found to be stereospecific, and the selectivity only depends on the / configuration of the starting -glycal.

Multivalent 9-O-Acetylated-sialic acid glycoclusters as potent inhibitors for SARS-CoV-2 infection.

The recent emergence of highly transmissible SARS-CoV-2 variants illustrates the urgent need to better understand the molecular details of the virus binding to its host cell and to develop anti-viral strategies. While many studies focused on the role of the angiotensin-converting enzyme 2 receptor in the infection, others suggest the important role of cell attachment factors such as glycans. Here, we use atomic force microscopy to study these early binding events with the focus on the role of sialic acids (SA).

Landscape composition drives the impacts of artificial light at night on insectivorous bats.

Among the most prevalent sources of biodiversity declines, Artificial Light At Night (ALAN) is an emerging threat to global biodiversity. Much knowledge has already been gained to reduce impacts. However, the spatial variation of ALAN effects on biodiversity in interaction with landscape composition remains little studied, though it is of the utmost importance to identify lightscapes most in need of action.

Pillar[5]arene-Based Polycationic Glyco[2]rotaxanes Designed as Antibiofilm Agents.

(P.A.) is a human pathogen belonging to the top priorities for the discovery of new therapeutic solutions.

What defines the maternal transcriptome?

In somatic cells, RNA polymerase II (Pol II) transcription initiation starts by the binding of the general transcription factor TFIID, containing the TATA-binding protein (TBP) and 13 TBP-associated factors (TAFs), to core promoters. However, in growing oocytes active Pol II transcription is TFIID/TBP-independent, as during oocyte growth TBP is replaced by its vertebrate-specific paralog TBPL2. TBPL2 does not interact with TAFs, but stably associates with TFIIA.

Dynamic Constitutional Frameworks as Antibacterial and Antibiofilm Agents.

Dynamic constitutional frameworks (DCFs) were synthesized and screened for biofilm inhibition or disruption. They are composed of a trialdehyde core reversibly linked to a diamine PEG connector and to a variety of neutral, anionic, or cationic heads, to generate a library of DCFs to generate multivalent dendritic architectures in the presence of Pseudomonas aeruginosa and Staphylococcus aureus. The best DCFs were always polycationic and the nature of the cationic heads significantly impact the antibiofilm activity.