Structural insights reveal a recognition feature for tailoring hydrocarbon stapled-peptides against the eukaryotic translation initiation factor 4E protein.

Stapled-peptides have emerged as an exciting class of molecules which can modulate protein-protein interactions. We have used a structure-guided approach to rationally develop a set of hydrocarbon stapled-peptides with high binding affinities and residence times against the oncogenic eukaryotic translation initiation factor 4E (eIF4E) protein. Crystal structures of these peptides in complex with eIF4E show that they form specific interactions with a region on the protein-binding interface of eIF4E which is distinct from the other well-established canonical interactions.

In1-ghrelin splicing variant is associated with reduced disease-free survival of breast cancer patients and increases malignancy of breast cancer cells lines.

Ghrelin gene generates several variants that regulate multiple pathophysiological functions, including tumor-related processes. In1-ghrelin is a splicing variant that was previously shown to be overexpressed in breast cancer (BCa), where it correlated with proliferation markers; however, its possible association with clinical outcome of BCa patients and underlying mechanisms are still unknown. To address this issue, expression levels and clinical associations of In1-ghrelin were analyzed in a cohort of 117 BCa samples.

In1-ghrelin splicing variant is overexpressed in pituitary adenomas and increases their aggressive features.

Pituitary adenomas comprise a heterogeneous subset of pathologies causing serious comorbidities, which would benefit from identification of novel, common molecular/cellular biomarkers and therapeutic targets. The ghrelin system has been linked to development of certain endocrine-related cancers. Systematic analysis of the presence and functional implications of some components of the ghrelin system, including native ghrelin, receptors and the recently discovered splicing variant In1-ghrelin, in human normal pituitaries (n = 11) and pituitary adenomas (n = 169) revealed that expression pattern of ghrelin system suffers a clear alteration in pituitary adenomasas compared with normal pituitary, where In1-ghrelin is markedly overexpressed.

Peptide therapeutics: targeting the undruggable space.

Rapid advancements in genomics have brought a better understanding of molecular mechanisms for various pathologies and identified a number of highly attractive target classes. Some of these targets include intracellular protein-protein interactions (PPIs), which control many essential biological pathways. Their surfaces are part of a diverse and unexplored biological space, where traditional small molecule scaffolds are not always successful.

Structural analysis of the human cannabinoid receptor one carboxyl-terminus identifies two amphipathic helices.

Recent research has implicated the C-terminus of G-protein coupled receptors in key events such as receptor activation and subsequent intracellular sorting, yet obtaining structural information of the entire C-tail has proven a formidable task. Here, a peptide corresponding to the full-length C-tail of the human CB1 receptor (residues 400-472) was expressed in E.coli and purified in a soluble form.

Identification of amino acid residues in BK virus VP1 that are critical for viability and growth.

BK virus (BKV) is a ubiquitous pathogen that establishes a persistent infection in the urinary tract of 80% of the human population. Like other polyomaviruses, the major capsid protein of BKV, virion protein 1 (VP1), is critical for host cell receptor recognition and for proper virion assembly. BKV uses a carbohydrate complex containing alpha(2,3)-linked sialic acid attached to glycoprotein and glycolipid motifs as a cellular receptor.

Activation of ERK, JNK, Akt, and G-protein coupled signaling by hybrid angiotensin II AT1/bradykinin B2 receptors expressed in HEK-293 cells.

Bradykinin (BK) and angiotensin II (AngII) often have opposite roles in cardiovascular diseases. Our aim here was to construct hybrid receptors which bind AngII but signal as BK. Various sequences of the intracellular face of the AngII type I receptor, AT1R, were replaced with corresponding sequences from the bradykinin B2 receptor (BKB2R).

The conformation of cyclo(-D-Pro-Ala4-) as a model for cyclic pentapeptides of the DL4 type.

The conformation of the cyclic pentapeptide cyclo(-D-Pro-Ala(4)-) in solution and in the solid state was reinvestigated using modern NMR techniques. To allow unequivocal characterization of hydrogen bonds, relaxation behavior, and intramolecular distances, differently labeled isotopomers were synthesized. The NMR results, supported by extensive MD simulations, demonstrate unambiguously that the preferred conformation previously described by us, but recently questioned, is indeed correct.

Structural features of parathyroid hormone receptor coupled to Galpha(s)-protein.

The molecular basis of the activation of G-proteins by the G-protein coupled receptor for parathyroid hormone (PTH) is unknown. Employing a combination of NMR methods and computer-based structural refinement, structural features involved in the activation of Galpha(s) by the PTH receptor (PTH1R) have been determined. Focusing on the C-terminus of the third intracellular loop (IC3), previously shown to be important for Galpha(s) activation by PTH1R, the structure of this region, PTH1R(402-408), while bound to Galpha(s), was determined by transferred nuclear Overhauser effect spectroscopy.

The role of sialic acid in human polyomavirus infections.

JC virus (JCV) and BK virus (BKV) are human polyomaviruses that infect approximately 85% of the population worldwide [1,2]. JCV is the underlying cause of the fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML), a condition resulting from JCV induced lytic destruction of myelin producing oligodendrocytes in the brain [3]. BKV infection of kidneys in renal transplant recipients results in a gradual loss of graft function known as polyomavirus associated nephropathy (PVN) [4].

Defining the retinoid binding site in the rod cyclic nucleotide-gated channel.

Rod vision is initiated when 11-cis-retinal, bound within rhodopsin, absorbs a photon and isomerizes to all-trans-retinal (ATR). This triggers an enzyme cascade that lowers cGMP, thereby closing cyclic nucleotide-gated (CNG) channels. ATR then dissociates from rhodopsin, with bright light releasing millimolar levels of ATR.

Modeling a sialic acid binding pocket in the external loops of JC virus VP1.

JC virus (JCV) is a common human polyomavirus that infects over 70% of the population worldwide. JCV has a restricted cell tropism that is caused partly by the initial interaction between the virus and sialic acid-containing host cell receptors. To identify the molecular interactions between the virus and its cellular receptor, we used a combined approach of site-directed mutagenesis and homology-based molecular modeling.

Cooperative interaction of arginine-19 and the N-terminal signaling domain in the affinity and potency of parathyroid hormone.

Residue 19 of parathyroid hormone (PTH) plays a unique role in the interaction process with the PTH1 receptor. A Glu(19) --> Arg(19) substitution, based on the Arg(19) of the PTH-related protein (PTHrP), increases the binding affinity when incorporated into the N-terminus of PTH [i.e.

Toward parathyroid hormone minimization: conformational studies of cyclic PTH(1-14) analogues.

The N-terminal fragment of PTH(1-34) is critical for PTH1 receptor activation. Various modifications of PTH(1-14) have been shown to result in a considerable increase in signaling potency [Shimizu et al. (2000) J.

19F MAS NMR quantification of accessible hydroxyl sites on fiberglass surfaces.

Solid-state 19F nuclear magnetic resonance (NMR) spectroscopy is used for the quantitative investigation of accessible hydroxyl sites on low surface area glass fibers. Samples with surface areas as low as 0.2 m2/g are investigated through covalent binding of (3,3,3-trifluoropropyl)dimethylchlorosilane.