The chemokines CCL5 and CXCL12 exhibit high-affinity binding to N-terminal peptides of the non-cognate receptors CXCR4 and CCR5, respectively.

CC and CXC chemokines are distinct chemokine subfamilies. CC chemokines usually do not bind CXC-chemokine receptors and vice versa. CCR5 and CXCR4 receptors are activated by CCL5 and CXCL12 chemokines, respectively, and are also used as HIV-1 coreceptors.

Multiple binding modes of an N-terminal CCR5-peptide in complex with HIV-1 gp120.

The N-terminal segment of CCR5 contains four tyrosine residues, sulphation of two of which is essential for high-affinity binding to gp120. In the present study, the interactions of gp120 with a 27-residue N-terminal CCR5 peptide sulphated at position Y10 and Y14, i.e.

Oligomerization of yeast α-factor receptor detected by fluorescent energy transfer between ligands.

G-protein-coupled receptors (GPCRs) comprise a large superfamily of transmembrane receptors responsible for transducing responses to the binding of a wide variety of hormones, neurotransmitters, ions, and other small molecules. There is extensive evidence that GPCRs exist as homo-and hetero-oligomeric complexes; however, in many cases, the role of oligomerization and the extent to which it occurs at low physiological levels of receptor expression in cells remain unclear. We report here the use of flow cytometry to detect receptor-receptor interactions based on fluorescence resonance energy transfer between fluorescently labeled cell-impermeant ligands bound to yeast α-mating pheromone receptors that are members of the GPCR superfamily.

The methyl C-edited/C-filtered transferred NOE for studying protein interactions with short linear motifs.

Many proteins interact with their ligand proteins by recognition of short linear motifs that are often intrinsically disordered. These interactions are usually weak and are characterized by fast exchange. NMR spectroscopy is a powerful tool to study weak interactions.

Allovalency observed by transferred NOE: interactions of sulfated tyrosine residues in the N-terminal segment of CCR5 with the CCL5 chemokine.

The N-terminal segment of the chemokine receptor Human CC chemokine receptor 5 (CCR5), Nt-CCR5, contains four tyrosine residues, Y3, Y10, Y14, and Y15. Sulfation of at least two of these tyrosine residues was found to be essential for high-affinity binding of CCR5 to its chemokine ligands. Here, we show that among the monosulfated Nt-CCR5(8-20) peptide surrogates (sNt-CCR5) those sulfated at Y15 and Y14 have the highest affinity for the CC chemokine ligand 5 (CCL5) chemokine in comparison with monosulfation at position Y10.

data: treatment with the F11R/JAM-A peptide 4D decreases mortality and reduces the generation of atherosclerotic plaques in ApoE-deficient mice.

The data in this article focus on the F11 Receptor (F11R/JAM-A; Junctional Adhesion Molecule-A; JAM-A, F11R), a cell adhesion protein constitutively expressed on the membrane surface of circulating platelets and localized within the tight junctions of healthy endothelial cells (ECs). Previous reports have shown that F11R/JAM-A plays a critical role in the adhesion of platelets to an inflamed endothelium due to its' pathological expression on the luminal surface of the cytokine-inflamed endothelium. Since platelet adhesion to an inflamed endothelium is an early step in the development of atherosclerotic plaque formation, and with time, resulting in heart attacks and stroke, we conducted a long-term, study utilizing the atherosclerosis-prone ApoE mice to attempt a blockade of the formation of atherosclerotic plaques by preventing the adhesion of platelets to the inflamed vasculature .

The feasibility of NaGdF nanoparticles as an x-ray fluorescence computed tomography imaging probe for the liver and lungs.

Purpose: As a novel imaging modality, x-ray fluorescence computed tomography (XFCT) can provide distribution and concentration information of contrast agents containing high atomic number elements, such as iodine, gadolinium, barium, gold, and platinum. Since XFCT has a better sensitivity and detection limit of high-Z elements compared with traditional and spectral CT, it becomes a powerful quantitative imaging tool for biological studies. The main problem of current XFCT imaging is its low emission and detection efficiency of x-ray fluorescence (XRF) photons.

Nitrocatecholic copolymers - synthesis and their remarkable binding affinity.

Nitrocatecholic random copolymers were obtained from nitration of protected catechol-N-isopropylacrylamide copolymers. Incorporation of 5% nitrocatecholic counits can lead to remarkable enhancement of the binding affinity toward FeO nanoparticles and an organic boronic acid by a factor of 40 and 20, respectively.

A peptide antagonist of F11R/JAM-A reduces plaque formation and prolongs survival in an animal model of atherosclerosis.

Background And Aims: The F11 Receptor (F11R), AKA Junctional Adhesion Molecule-A (JAM-A) (F11R/JAM-A), is an adhesion protein constitutively expressed on the membrane surface of circulating platelets and the luminal surface of inflamed endothelial cells (EC). Platelet adhesion to an inflamed endothelium is one of the early steps of atherosclerotic plaque formation. Our previous studies, conducted with cultured EC in vitro, have demonstrated the expression of F11R/JAM-A on the luminal surface of inflamed EC, platelet adhesion to inflamed EC through F11R/JAM-A interactions, and inhibition of this interaction by the presence of F11R/JAM-A antagonistic peptide (F11Rpeptide 4D).

The Synthesis of Sulfated CCR5 Peptide Surrogates and their Use to Study Receptor-Ligand Interactions.

Background: Tyrosine sulfation is an important post-translational modification of secreted and membrane proteins in multi-cellular organisms. This modification is catalyzed by tyrosylprotein sulfotransferases that often modify tyrosine residues in their target substrates in a heterogeneous manner. Chemokine receptors such as CCR5, which play roles in inflammation, immunity and viral infection, are sulfated on tyrosine residues in their extracellular N-termini.

Ir(COD)Cl]/Tris(2,4-di--butylphenyl)phosphite-Catalyzed Addition Reactions of Arylboronic Acids with Aldehydes.

[Ir(COD)Cl]/tris(2,4-di--butylphenyl)phosphite-catalyzed addition reactions of arylboronic acids with aldehydes were described. The Ir(I) catalyst, generated from [Ir(COD)Cl] and tris(2,4-di--butylphenyl)phosphite, was an efficient catalyst system for the addition reactions of a variety of arylboronic acids with aromatic and aliphatic aldehydes. The easy availability of the catalyst and good yields make these reactions potentially useful in organic synthesis.

Defining specific residue-to-residue interactions between the gp120 bridging sheet and the N-terminal segment of CCR5: applications of transferred NOE NMR.

Infection by HIV-1 requires protein-protein interactions involving gp120, CD4 and CCR5. We have previously demonstrated that the transferred nuclear Overhauser effect (TRNOE), in combination with asymmetric deuteration of a protein and a peptide ligand can be used to detect intermolecular interactions in large protein complexes with molecular weights up to ~ 100 kDa. Here, using this approach, we reveal interactions between tyrosine residues of a 27-residue peptide corresponding to the N-terminal segment of the CCR5 chemokine receptor, and a dimeric extended core gp120 envelope protein of HIV-1 complexed with a CD4-mimic miniprotein.

The solution structure of monomeric CCL5 in complex with a doubly sulfated N-terminal segment of CCR5.

Unlabelled: The inflammatory chemokine CCL5, which binds the chemokine receptor CCR5 in a two-step mechanism so as to activate signaling pathways in hematopoetic cells, plays an important role in immune surveillance, inflammation, and development as well as in several immune system pathologies. The recently published crystal structure of CCR5 bound to a high-affinity variant of CCL5 lacks the N-terminal segment of the receptor that is post-translationally sulfated and is known to be important for high-affinity binding. Here, we report the NMR solution structure of monomeric CCL5 bound to a synthetic doubly sulfated peptide corresponding to the missing first 27 residues of CCR5.

Controlled Pd(0)/AdP-Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with AdP-Coordinated Acetanilide-Based Palladacycle Complex as Initiator.

Controlled Pd(0)-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers with tris(1-adamantyl)phosphine (AdP) as the ligand was described. AdP-coordinated acetanilide-based palladacycle complex () was demonstrated to be an efficient initiator for controlled Suzuki cross-coupling polymerization, affording polymers with narrow s and well-controlled end groups. Our study provided an efficient ligand and an efficient initiator for controlled Suzuki cross-coupling polymerizations.

Uptake Assay for Radiolabeled Peptides in Yeast.

We describe an assay for measuring the uptake of radioactive peptides into the yeast . The methods presented here can be adapted to measure a variety of substrates transported into any bacterial or fungal cell via specific carrier-mediated systems.

Electron-Poor, Fluoro-Containing Arylboronic Acids as Efficient Coupling Partners for Bis(1,5-cyclooctadiene)nickel(0)/Tricyclohexylphosphine-Catalyzed Cross-Coupling Reactions of Aryl Arenesulfonates.

The use of electron-poor, fluoro-containing arylboronic acids as general coupling partners for nickel(0) /tricyclohexylphosphine-catalyzed cross-coupling of aryl arenesulfonates is described. Electron-poor fluoro-containing arylboronic acids were found to react, faster than electron-rich/neutral arylboronic acids, with (4-methoxyphenyl)(4-methylbenzenesulfonato-κ)bis(tricyclohexylphosphine)nickel. Bis(1,5-cyclooctadiene)nickel(0)/tricyclohexylphosphine, (4-methoxyphenyl)(4-methylbenzenesulfonato-κ)bis(tricyclohexylpho sphine)nickel and bis(tricyclohexylphosphine)nickel (II) bromide were all found to be efficient catalysts/catalyst precursors.

Quantum gravity and taoist cosmology: Exploring the ancient origins of phenomenological string theory.

This paper carries forward the author's contribution to PBMP's previous special issue on Integral Biomathics (Rosen 2015). In the earlier paper, the crisis in contemporary theoretical physics was described and it was demonstrated that the problem can be addressed effectively only by shifting the foundations of physics from objectivist Cartesian philosophy to phenomenological philosophy. To that end, a phenomenological string theory was proposed based on qualitative topology and hypercomplex numbers.

Halo Assay for Toxic Peptides and Other Compounds in Microorganisms.

Unlabelled: We describe an assay for determination of toxicity in involving spotting of a toxic peptide on a lawn of yeast cells. This assay may be generalized to determine toxicity of a variety of compounds by substituting a putative toxic compound in place of the peptide. The general protocol may also be used to determine toxicity of any small compound toward another microorganism by replacing with the target microbe and modifying growth conditions accordingly.

Detection of intermolecular transferred-NOE interactions in small and medium size protein complexes: RANTES complexed with a CCR5 N-terminal peptide.

NMR is a powerful tool for studying structural details of protein/peptide complexes exhibiting weak to medium binding (K > 10 μm). However, it has been assumed that intermolecular nuclear Overhauser effect (NOE) interactions are difficult to observe in such complexes. We demonstrate that intermolecular NOEs can be revealed by combining the C-edited/ C-filtered experiment with the transferred NOE effect (TRNOE).

NIR upconversion fluorescence glucose sensing and glucose-responsive insulin release of carbon dot-immobilized hybrid microgels at physiological pH.

This work reports the preparation of multifunctional hybrid microgels based on the one-pot free radical dispersion polymerization of hydrogen-bonding complexes in water, formed from hydroxyl/carboxyl bearing carbon dots with 4-vinylphenylboronic acid and acrylamide comonomers, which can realize the simultaneous optical detection of glucose using near infrared light and glucose-responsive insulin delivery.

Immunofocusing using conformationally constrained V3 peptide immunogens improves HIV-1 neutralization.

V3-directed antibodies are present in practically all HIV-1 infected patients and in individuals vaccinated with gp120. The levels of maternal V3-directed antibodies were recently shown to correlate with reduced mother to child transmission, and V3 IgGs were found to be a negative correlate of risk in the RV-144 human trial. mAb directed to the tip of the V3 are capable of broad neutralization of Tier-1 and some Tier-2 viruses.

Detection of intermolecular NOE interactions in large protein complexes.

Intermolecular NOE interactions are invaluable for structure determination of biomolecular complexes by NMR and they represent the "gold-standard" amongst NMR measurements for characterizing interfaces. These NOEs constitute only a small fraction of the observed NOEs in a complex and are usually weaker than many of the intramolecular NOEs. A number of methods have been developed to remove the intramolecular NOEs that interfere with the identification of intermolecular NOEs.

Detection of intermolecular transferred NOEs in large protein complexes using asymmetric deuteration: HIV-1 gp120 in complex with a CCR5 peptide.

Weak protein-protein and protein-ligand interactions play important roles in biological recognition. In many cases, simplification of structural studies of large protein complexes is achieved by investigation of the interaction between the protein and a weakly binding segment of its protein ligand. Detection of pairwise interactions in such complexes is a major challenge for both X-ray crystallography and nuclear magnetic resonance.

Variable Dependence of Signaling Output on Agonist Occupancy of Ste2p, a G Protein-coupled Receptor in Yeast.

We report here on the relationship between ligand binding and signaling responses in the yeast pheromone response pathway, a well characterized G protein-coupled receptor system. Responses to agonist (α-factor) by cells expressing widely varying numbers of receptors depend primarily on fractional occupancy, not the absolute number of agonist-bound receptors. Furthermore, the concentration of competitive antagonist required to inhibit α-factor-dependent signaling is more than 10-fold higher than predicted based on the known ligand affinities.

The C4 region as a target for HIV entry inhibitors--NMR mapping of the interacting segments of T20 and gp120.

The peptide T20, which corresponds to a sequence in the C-terminal segment of the HIV-1 transmembrane glycoprotein gp41, is a strong entry inhibitor of HIV-1. It has been assumed that T20 inhibits HIV-1 infection by binding to the trimer formed by the N-terminal helical region (HR1) of gp41, preventing the formation of a six helix bundle by the N- and C-terminal helical regions of gp41. In addition to binding to gp41, T20 was found to bind to gp120 of X4 viruses and this binding was suggested to be responsible for an alternative mechanism of HIV-1 inhibition by this peptide.