Constrained Peptides Mimic a Viral Suppressor of RNA Silencing

The structure-based design of constrained alpha-helical peptides derived from the viral suppressor of RNA silencing TAV2b is described. We observe that the introduction of two inter-side chain crosslinks provides peptides with increased alpha-helicity and protease stability. One of these modified peptides (B3) shows high affinity for different double-stranded RNA structures including a palindromic siRNA as well as microRNA-21 and its precursor pre-miR-21. Notably, B3 binding to pre-miR-21 inhibits Dicer processing in a biochemical assay. As a further characteristic this peptide also exhibits cellular entry. <br>

Constrained Peptides Mimic a Viral Suppressor of RNA Silencing

The structure-based design of constrained alpha-helical peptides derived from the viral suppressor of RNA silencing TAV2b is described. We observe that the introduction of two inter-side chain crosslinks provides peptides with increased alpha-helicity and protease stability. One of these modified peptides (B3) shows high affinity for different double-stranded RNA structures including a palindromic siRNA as well as microRNA-21 and its precursor pre-miR-21. Notably, B3 binding to pre-miR-21 inhibits Dicer processing in a biochemical assay. As a further characteristic this peptide also exhibits cellular entry. <br>

555 Inhibition of FOXP3 by stapled alpha-helical peptides alters Regulatory T Cell function

BackgroundRegulatory T cells (Tregs) have been a therapeutic target of interest since early pre-clinical work revealed that their depletion led to enhanced tumor control. Despite continuing advances in the development of novel cellular-, antibody- and chemotherapeutic-based strategies to increase anti-tumor immunity, Treg presence and activity within the tumor microenvironment remains a complicating factor to their clinical efficacy. To overcome dosing limitations and off-target effects from antibody-based Treg deletional strategies, we investigated the ability to target FOXP3, the master regulator of Treg development, maintenance, and suppressive function using hydrocarbon stapled alpha-helical peptides (SAHs). We developed SAHs in the likeness of a portion of the native FOXP3 antiparallel coiled-coil homodimerization domain, in an effort to impede FOXP3 transcriptional function. SAHs overcome three major protein-protein interaction (PPI) therapeutic hurdles, namely: cellular penetrance, target specificity, and secondary structure stability. Our overall goal is to use these SAHs as investigatory drugs to demonstrate proof-of concept of the druggability of FOXP3. We aim to show their utility to further understand FOXP3 transcriptional dynamics and explore their potential use in altering the immune landscape in combination with other immune-focused therapies.MethodsUtilizing the FOXP3 crystal structure as a guide, we developed a number of single and double SAH peptides corresponding to the leucine zipper homodimerization domain (DD) of FOXP3 (SAH-FOXP3DDs). We tested the ability of SAH-FOXP3DDs to bind FOXP3, to access the intracellular compartment, to alter Treg transcriptional and phenotypic profiles, and to inhibit Treg-mediated immune suppression.ResultsSelect SAH-FOXP3DDs bound recombinant FOXP3ΔN and the FOXP3 leucine zipper (LZCC) domain with high affinity and dose-dependently inhibited binding of FOXP3 to cognate DNA in vitro. Lead SAH-FOXP3DDs were cell permeable and showed no non-specific toxicity to T cells at high concentrations. Flow cytometric and qRT-PCR analysis of treated Tregs revealed dose-dependent changes in protein and gene expression of several FOXP3 targets suggestive of FOXP3-specific transcriptional alteration. Treatment of Tregs with lead SAHs effectively inhibited in vitro Treg-mediated T cell suppression and induced global gene expression changes corresponding to loss of function Foxp3 in vivo.ConclusionsThis work supports the ability of SAHs to target transcription factors, particularly as a method of interrogating specific PPI functions, and provides strong proof-of-principle evidence that FOXP3 is druggable. SAH-FOXP3DDs will not only further our understanding of FOXP3 transcriptional control but will serve as prototype therapeutics whereby we can explore their ability to amplify anti-tumor immunity in pre-clinical tumor models.

Peptide–Oleate Complexes Create Novel Membrane-Bound Compartments

A challenging question in evolutionary theory is the origin of cell division and plausible molecular mechanisms involved. Here, we made the surprising observation that complexes formed by short alpha-helical peptides and oleic acid can create multiple membrane-enclosed spaces from a single lipid vesicle. The findings suggest that such complexes may contain the molecular information necessary to initiate and sustain this process. Based on these observations, we propose a new molecular model to understand protocell division.

Impact of oxetane incorporation on the structure and stability of alpha-helical peptides

Here we reveal the tolerance of oxetane modification within alpha helical peptides using a combined molecular dynamics and experimental biophysics approach.

Molecular interactions between single layered MoS2 and biological molecules

In this research, molecular interactions between several de novo designed alpha-helical peptides and monolayer MoS2 have been studied.