Proteomimetics as protein-inspired scaffolds with defined tertiary folding patterns

Proteins have evolved as a variable platform that provides access to molecules with diverse shapes, sizes and functions. These features have inspired chemists for decades to seek artificial mimetics of proteins with improved or novel properties. Such work has focused primarily on small protein fragments, often isolated secondary structures; however, there has lately been a growing interest in the design of artificial molecules that mimic larger, more complex tertiary folds. In this Perspective, we define these agents as ‘proteomimetics’ and discuss the recent advances in the field. Proteomimetics can be divided into three categories: protein domains with side-chain functionality that alters the native linear-chain topology; protein domains in which the chemical composition of the polypeptide backbone has been partially altered; and protein-like folded architectures that are composed entirely of non-natural monomer units. We give an overview of these proteomimetic approaches and outline remaining challenges facing the field

In Situ Cyclization of Proteins (INCYPRO):Cross-Link Derivatization Modulates Protein Stability

Protein macrocyclization represents a very efficient strategy to increase the stability of protein tertiary structures. Here, we describe a panel of novel C3-symmetric tris-electrophilic agents and their use for the cyclization of proteins. These electrophiles are reacted with a protein domain harboring three solvent-exposed cysteine residues, resulting in the in situ cyclization of the protein (INCYPRO). We observe a clear dependency of cross-linking rates on the electrophilicity. All nine obtained cross-linked protein versions show considerably increased thermal stability (up to 29 °C increased melting temperature) when compared to that of the linear precursor. Most interestingly, the degree of stabilization correlates with the hydrophilicity of the cross-link. These results will support the development of novel cross-linked proteins and enable a more rational design process

Inhibition of Oncogenic Wnt Signaling through Direct Targeting of β-Catenin

Aberrant activation of signaling by the Wnt pathway is strongly implicated in the onset and progression of numerous types of cancer. Owing to the persistent dependence of these tumors on Wnt signaling for growth and survival, inhibition of this pathway is considered an attractive mechanism-based therapeutic approach. Oncogenic activation of Wnt signaling can ensue from a variety of distinct aberrations in the signaling pathway, but most share the common feature of causing increased cellular levels of β-catenin by interfering with its constitutive degradation. β-Catenin serves as a central hub in Wnt signaling by engaging in crucial protein–protein interactions with both negative and positive effectors of the pathway. Direct interference with these protein–protein interactions is a biologically compelling approach toward suppression of β-catenin hyperactivity, but such interactions have proven intransigent with respect to small-molecule targeting. Hence β-catenin remains an elusive target for translational cancer therapy. Here we report the discovery of a hydrocarbon-stapled peptide that directly targets β-catenin and interferes with its ability to serve as a transcriptional coactivator for T-cell factor (TCF) proteins, the downstream transcriptional regulators of the Wnt pathway.Chemistry and Chemical BiologyStem Cell and Regenerative Biolog

Stapling of Peptides Potentiates the Antibiotic Treatment of Acinetobacter baumannii In Vivo

The rising incidence of multidrug resistance in Gram-negative bacteria underlines the urgency for novel treatment options. One promising new approach is the synergistic combination of antibiotics with antimicrobial peptides. However, the use of such peptides is not straightforward; they are often sensitive to proteolytic degradation, which greatly limits their clinical potential. One approach to increase stability is to apply a hydrocarbon staple to the antimicrobial peptide, thereby fixing them in an α-helical conformation, which renders them less exposed to proteolytic activity. In this work we applied several different hydrocarbon staples to two previously described peptides shown to act on the outer membrane, L6 and L8, and tested their activity in a zebrafish embryo infection model using a clinical isolate of Acinetobacter baumannii as a pathogen. We show that the introduction of such a hydrocarbon staple to the peptide L8 improves its in vivo potentiating activity on antibiotic treatment, without increasing its in vivo antimicrobial activity, toxicity or hemolytic activity

Cell permeable stapled peptide inhibitor of Wnt signaling that targets β-catenin protein‒protein interactions

The Wnt signaling pathway plays a critical role in cell proliferation and differentiation, thus it is often associated with diseases such as cancers. Unfortunately, although attractive, developing anti-cancer strategy targeting Wnt signaling has been challenging given that the most attractive targets are involved in protein-protein interactions (PPIs). Here, we develop a stapled peptide inhibitor that targets the interaction between β-catenin and T cell factor/lymphoid enhancer-binding factor transcription factors, which are crucially involved in Wnt signaling. Our integrative approach combines peptide stapling to optimize proteolytic stability, with lessons learned from cell-penetrating peptide (CPP) design to maximize cellular uptake resulting in NLS-StAx-h, a selective, cell permeable, stapled peptide inhibitor of oncogenic Wnt signaling that efficiently inhibits β-catenin-transcription factor interactions. We expect that this type of integrative strategy that endows stapled peptides with CPP features will be generally useful for developing inhibitors of intracellular PPIs

LEGO® bricks as building blocks for centimeter-scale biological environments

LEGO bricks are commercially available interlocking pieces of plastic that are conventionally used as toys. We describe their use to build engineered environments for cm-scale biological systems, in particular plant roots. Specifically, we take advantage of the unique modularity of these building blocks to create inexpensive, transparent, reconfigurable, and highly scalable environments for plant growth in which structural obstacles and chemical gradients can be precisely engineered to mimic soil

Pojava mikotoksina u vodenom okolišu zbog njihove prisutnosti u usjevima

The aim of this study was to establish a relation between zearalenone contamination of crops in the Polish province of Wielkopolska and its occurrence in aquatic ecosystems close by the crop fields. Water samples were collected from water bodies such as drainage ditches, wells, or watercourses located in four agricultural areas. Moreover, control water samples were collected from the Bogdanka river, which was located outside the agricultural areas and near an urban area. Cereal samples were collected in the harvest season from each agricultural area close to tested water bodies. Zearalenone (ZEA) was found in all water and cereal samples. The highest concentrations were recorded in the postharvest season (September to October) and the lowest in the winter and spring. Mean ZEA concentrations in water ranged between 1.0 ng L-1 and 80.6 ng L-1, and in cereals from 3.72 ng g-1 to 28.97 ng g-1. Our results confi rm that mycotoxins are transported to aquatic systems by rain water through soil.Cilj ovog istraživanja bio je pojasniti učestalost pojave mikotoksina u vodenim ekosustavima i njihove korelacije sa stupnjem zaraze žitarica (uzgajanih u blizini vodospremnika), čija su zrna onečišćena (kontaminirana) mikotoksinima te problem prolaska mikotoksina kroz tlo u vodeni okoliš (onečišćenje podzemnih voda mikotoksinima). Uzorci vode prikupljeni su u regiji Wielkopolska iz vodenih tijela poput odvodnih jaraka i zdenaca, odnosno vodotoka smještenih u područjima koja se rabe za poljoprivredu. Dio uzoraka vode prikupljen je iz rijeke Bogdanka, u rubnom području grada Poznańa. U sezoni žetve sa svake poljoprivredne površine smještene u neposrednoj blizini testiranih vodenih tijela prikupljeni su uzorci žitarica. U svim analiziranim uzorcima vode i žitarica potvrđena je prisutnost zearalenona (ZEA). Najviše koncentracije mikotoksina u uzorcima sa svih poljoprivrednih površina zabilježene su u jesen nakon sezone žetve (rujan-listopad), dok su najniže vrijednosti izmjerene zimi i u proljeće. Srednje koncentracije zearalenona u vodi bile su u rasponu od 1,0 ng L-1 do 80,6 ng L-1. U žitarica je prosječna razina zearalenona iznosila 3,72 ng g-1 do 28,97 ng g-1, što govori u prilog vjerodostojnosti naše polazišne hipoteze o prijenosu mikotoksina kroz tlo nakon njihova ispiranja s površine u jarke za odvodnju