Project description:Many functions of proteins are performed by independently folding structural units called domains. These domains are structurally conserved but not identical in different proteins. Here, to understand the consequences for regulation and evolvability of domain extensions, we quantify the energetic effects of two extensions in a model protein domain. Quantifying abundance and ligand binding for >190,000 protein variants allows us to measure the free energy changes for mutations throughout a PDZ domain and ~7000 energetic couplings between these mutations and two domain extensions. Both a structured extension and a more dynamic extension substantially but specifically re-shape the energy landscape. In particular, deleting an ɑ-helix alters the energetic consequences of >400 mutations in >50 sites on fold stability or binding energy, and the effects of >300 allosteric mutations, including at solvent-accessible surface sites. Extending or pruning the domain therefore reshapes its energetic and allosteric landscape, adding and removing opportunities for the allosteric control of protein function.
Project description:Allosteric communication between distant sites in proteins is central to nearly all biological regulation but still poorly characterised for most proteins, limiting conceptual understanding, biological engineering and allosteric drug development. Typically only a few allosteric sites are known in model proteins, but theoretical, evolutionary and some experimental studies suggest they may be much more widely distributed. An important reason why allostery remains poorly characterised is the lack of methods to systematically quantify long-range communication in diverse proteins. Here we address this shortcoming by developing a method that uses deep mutational scanning to comprehensively map the allosteric landscapes of protein interaction domains. The key concept of the approach is the use of ‘multidimensional mutagenesis’: mutational effects are quantified for multiple molecular phenotypes—here binding and protein abundance—and in multiple genetic backgrounds. This is an efficient experimental design that allows the underlying causal biophysical effects of mutations to be accurately inferred en masse by fitting thermodynamic models using neural networks. We apply the approach to two of the most common human protein interaction domains, an SH3 domain and a PDZ domain, to produce the first global atlases of allosteric mutations for any proteins. Allosteric mutations are widely dispersed with extensive long-range tuning of binding affinity and a large mutational target space of network-altering ‘edgetic’ variants. Mutations are more likely to be allosteric closer to binding interfaces, at Glycines in secondary structure elements and at particular sites including a chain of residues connecting to an opposite surface in the PDZ domain. This general approach of quantifying mutational effects for multiple molecular phenotypes and in multiple genetic backgrounds should allow the energetic and allosteric landscapes of many proteins to be rapidly and comprehensively mapped.
Project description:The K14E6 transgenic mice develop skin hyperplasia, benign tumors, and cancer in the dorsal skin spontaneously. The E6 oncoprotein own its tumorigenic potential to a region located near the C-Terminal domain, better known as the PDZ ligand-domain. The aim of this work was to describe early cellular processes affected by the E6’s PDZ ligand-domain when is expressed in the skin of transgenic mice using microarray technology. Results. A total of 222 genes were differentially expressed (FC:1.5, Adj.p.value <0.05, and b value > 0.5) in the skin of K14E6 mice as compared to K14E6Δ146-151 mice. Out of those, 70 genes were up-regulated and 151 genes were down-regulated. Enzyme linked receptor protein signaling was the most affected process in our data, followed by cell adhesion, development, and lipid biosynthesis. We also found that the K14E6 strains induces the mRNA of the wound-inducible gene K6b, and delocalizes E-cadherin protein in the entire epidermis. Finally, CD34 and K15 epidermal stem cell marker proteins diminish its expression in the skin, in a PDZ-dependent manner. Conclusions. The PDZ ligand-domain of HPV16-E6 oncoprotein affects the expression of several genes involved in cellular processes that could be relevant in the HPV-induced carcinogenesis. Since HPV16-E6 oncoproteins lacking the PDZ ligand-domain loose its oncogenic potential, the knowledge of genes transcriptionally affected by the E6’s PDZ ligand-domain will provide valuable information about HPV-induced skin carcinogenesis.
Project description:The K14E6 transgenic mice developskin hyperplasia,benign tumors and skin cancer. The tumor formation capacity diminishes when E6 lacks its PDZ ligand-motif. This study aims to compare the transciptional profiles of transgenic K14E6 mice with K14E6 Δ146-151 (lacking the PDZ domain) in order to explore the role of PDZ in early skin carcinogenesis. Skin tissue from three different strains of mice were dissected for RNA extraction, processing and hybridization in Affymetrix Mouse Genome 430 2,0 array. We processed three biological replicates per strain. 3 mice were used for each replicate pool for a final RNA concentration of 3 micrograms. The arrays were analyzed using Partek Genomics suite software.
Project description:The K14E6 transgenic mice developskin hyperplasia,benign tumors and skin cancer. The tumor formation capacity diminishes when E6 lacks its PDZ ligand-motif. This study aims to compare the transciptional profiles of transgenic K14E6 mice with K14E6 Δ146-151 (lacking the PDZ domain) in order to explore the role of PDZ in early skin carcinogenesis.
Project description:Designing highly specific modulators of protein-protein interactions (PPIs) is especially challenging in the context of multiple paralogs and conserved interaction surfaces. In this case, direct generation of selective and competitive inhibitors is hindered by high similarity within the evolutionary-related protein interfaces and PPI domains. We report here a strategy that addresses this challenge by using a semi-rational approach that separates the modulator design into two functional parts. We first achieve specificity toward a region outside of the interface by employing a selection by phage display coupled with molecular and cellular validation. Highly selective competition is then generated by appending the more degenerate interaction peptide to bind against the target interface. We have applied this approach to PSD-95, an essential multi-PDZ domain-containing synaptic scaffold protein that belongs to a larger family of paralogs. We show here that with this strategy we could specifically target a single PDZ domain within the postsynaptic protein PSD-95 over highly similar PDZ domains in PSD-93, SAP-97 and SAP-102. Our work provides the first paralog-selective and domain specific inhibitor of PSD-95, and describes a method to efficiently target other conserved PPI modules. This archive contains the comparative LC/MS/MS analysis of cellular targets of an engineered selective PSD-95 PDZ domain ligand, Xph20-ETWV, against the fusion with a naïve clone, Xph0-ETWV and a control non-binding protein (mSacrlet-i).
Project description:The culture supernatant of wild-type (WT) Vibrio cholerae N16961 and mutant epsC∆PDZ strains were compared to determine which, if any, type II secretion system substrates were affected by the deletion of the PDZ domain of EpsC