Journal articles

p53 is frequently mutated in human cancers. Its levels are tightly regulated by the E3 ubiquitin ligase MDM2. The complex between MDM2 and p53 is largely formed by the interaction between the N-terminal domain of MDM2 and the N-terminal transactivation (TA) domain of p53 (residues 15-29). We investigated the kinetic and thermodynamic basis of the MDM2/p53 interaction by using wild-type and mutant variants of the TA domain. We focus on the effects of phosphorylation at positions Thr18 and Ser20 including their substitution with phosphomimetics.

Consensus-designed tetratricopeptide repeat proteins (CTPRs) are highly stable, modular proteins that are strikingly amenable to rational engineering. They therefore have tremendous potential as building blocks for biomaterials and biomedicine. Here we explore the possibility of extending the loops between repeats to enable further diversification, and we investigate how this modification affects stability and folding cooperativity.

Harnessing and controlling self-assembly is an important step in developing proteins as novel biomaterials. With this goal, here we report the design of a general genetically programmed system that covalently concatenates multiple distinct protein domains into specific assembled arrays. It is driven by iterative intein-mediated native chemical ligation (NCL) under mild native conditions. The system uses a series of initially inert recombinant protein fusions that sandwich the protein modules to be ligated between one of a number of different affinity tags and an intein protein domain.

The term allostery was originally developed to describe structural changes in one binding site induced by the interaction of a partner molecule with a distant binding site [1], and it has been studied in depth in the field of enzymology [2–5]. Here we discuss the concept of action at a distance in relation to the folding and function of the solenoid class of tandem-repeat proteins such as tetratricopeptide repeats and ankyrin repeats. Distantly located repeats have a fold cooperatively, even though only nearest-neighbour interactions exist in these proteins.

For many years, curve fitting software has been heavily utilized to fit simple models to various types of biophysical data. Although such software packages are easy to use for simple functions, they are often expensive and present substantial impediments to applying more complex models or for the analysis of large datasets. One field that is relient on such data analysis is the thermodynamics and kinetics of protein folding. Over the past decade, increasingly sophisticated analytical models have been generated, but without simple tools to enable routine analysis.

Background

Quantitative determination of protein thermodynamic stability is fundamental to many research areas, both basic and applied. Although chemical-induced denaturation is the gold-standard method, it has been replaced in many settings by semi-quantitative approaches such as thermal stability measurements. The reason for this shift is that chemical denaturation experiments are labour-intensive, sample-costly and time-consuming, and it has been assumed that miniaturisation to a high-throughput format would not be possible without concomitantly comprising data quality.

Stapled peptides have arisen as a new class of chemical probe and potential therapeutic agents to modulate protein-protein interactions. Here, we report the first two-component i,i+7 stapling methodology using two orthogonal, on-resin stapling reactions to incorporate linkers bearing a chiral center on a p53-derived stapled peptide. Post-stapling modifications to the staple chain were performed on-resin, enabling rapid access to various peptide derivatives from a single staple.

We report a double-click macrocyclization approach for the design of constrained peptide inhibitors having non-helical or extended conformations. Our targets are the tankyrase proteins (TNKS), poly(ADP-ribose) polymerases (PARP) that regulate Wnt signaling by targeting Axin for degradation. TNKS are deregulated in many different cancer types, and inhibition of TNKS therefore represents an attractive therapeutic strategy. However, clinical development of TNKS-specific PARP catalytic inhibitors is challenging due to off-target effects and cellular toxicity.