scholarly journals Structure of the Notch1-negative regulatory region: implications for normal activation and pathogenic signaling in T-ALL

Blood ◽  
2009 ◽  
Vol 113 (18) ◽  
pp. 4381-4390 ◽  
Author(s):  
Wendy R. Gordon ◽  
Monideepa Roy ◽  
Didem Vardar-Ulu ◽  
Megan Garfinkel ◽  
Marc R. Mansour ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Structural Integrity ◽  
Crystal Packing ◽  
Novel Mutation ◽  
Lymphoblastic Leukemia ◽  
Regulatory Region ◽  
Point Mutations ◽  
Protein Protein Interactions ◽  
Proteolytic Resistance ◽  
Cell Acute Lymphoblastic Leukemia

Abstract Proteolytic resistance of Notch prior to ligand binding depends on the structural integrity of a negative regulatory region (NRR) of the receptor that immediately precedes the transmembrane segment. The NRR includes the 3 Lin12/Notch repeats and the juxtamembrane heterodimerization domain, the region of Notch1 most frequently mutated in T-cell acute lymphoblastic leukemia lymphoma (T-ALL). Here, we report the x-ray structure of the Notch1 NRR in its autoinhibited conformation. A key feature of the Notch1 structure that maintains its closed conformation is a conserved hydrophobic plug that sterically occludes the metalloprotease cleavage site. Crystal packing interactions involving a highly conserved, exposed face on the third Lin12/Notch repeat suggest that this site may normally be engaged in intermolecular or intramolecular protein-protein interactions. The majority of known T-ALL–associated point mutations map to residues in the hydrophobic interior of the Notch1 NRR. A novel mutation (H1545P), which alters a residue at the crystal-packing interface, leads to ligand-independent increases in signaling in reporter gene assays despite only mild destabilization of the NRR, suggesting that it releases the autoinhibitory clamp on the heterodimerization domain imposed by the Lin12/Notch repeats. The Notch1 NRR structure should facilitate a search for antibodies or compounds that stabilize the autoinhibited conformation.

Structure of the Notch1 Negative Regulatory Region: Implications for Normal Activation and Pathogenic Signaling in T-ALL

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3798-3798
Author(s):  
Wendy Ryan Gordon ◽  
Mondeepa Roy ◽  
Didem Vardar-Ulu ◽  
Megan Garfinkel ◽  
Marc R Mansour ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Structural Integrity ◽  
Crystal Packing ◽  
Novel Mutation ◽  
Regulatory Region ◽  
Point Mutations ◽  
Lymphocytic Leukemia ◽  
Protein Protein Interactions ◽  
Proteolytic Resistance ◽  
Packing Interactions

Abstract Proteolytic resistance of Notch prior to ligand binding depends on the structural integrity of a negative regulatory region (NRR) of the receptor that immediately precedes the transmembrane segment. The NRR includes the three Lin12/Notch repeats and the juxtamembrane heterodimerization domain, the region of Notch1 most frequently mutated in T cell acute lymphocytic leukemia. Here, we report the X-ray structure of the Notch1 NRR determined to 2.0 Å resolution in its autoinhibited conformation. A key feature of the Notch1 structure that maintains its closed conformation is a conserved hydrophobic plug that sterically occludes the metalloprotease cleavage site. Crystal packing interactions involving a highly conserved, exposed face on the third Lin12/Notch repeat suggest that this site may normally be engaged in inter- or intra-molecular protein-protein interactions. The vast majority of known T-ALL-associated point mutations of human Notch1 map to residues in the hydrophobic interior of the NRR. A novel mutation (H1545P), which alters a residue at the crystal-packing interface, leads to ligand-independent increases in signaling in reporter gene assays despite only mild destabilization of the NRR, suggesting that it releases the autoinhibitory clamp on the heterodimerization domain imposed by the Lin12/Notch repeats. The Notch1 NRR structure should facilitate a search for antibodies or compounds that stabilize the autoinhibited conformation.

scholarly journals Mechanism and bottlenecks in strand photodissociation of split green fluorescent proteins (GFPs)

2017 ◽  
Vol 114 (11) ◽  
pp. E2146-E2155 ◽  
Author(s):  
Chi-Yun Lin ◽  
Johan Both ◽  
Keunbong Do ◽  
Steven G. Boxer
Keyword(s):  
Quantum Yield ◽  
Protein Interactions ◽  
Fluorescent Proteins ◽  
Point Mutations ◽  
Photoactive Yellow Protein ◽  
Green Fluorescent Proteins ◽  
Protein Protein Interactions ◽  
Low Efficiency ◽  
Green Fluorescent ◽  
Rate Limiting

Split GFPs have been widely applied for monitoring protein–protein interactions by expressing GFPs as two or more constituent parts linked to separate proteins that only fluoresce on complementing with one another. Although this complementation is typically irreversible, it has been shown previously that light accelerates dissociation of a noncovalently attached β-strand from a circularly permuted split GFP, allowing the interaction to be reversible. Reversible complementation is desirable, but photodissociation has too low of an efficiency (quantum yield <1%) to be useful as an optogenetic tool. Understanding the physical origins of this low efficiency can provide strategies to improve it. We elucidated the mechanism of strand photodissociation by measuring the dependence of its rate on light intensity and point mutations. The results show that strand photodissociation is a two-step process involving light-activated cis-trans isomerization of the chromophore followed by light-independent strand dissociation. The dependence of the rate on temperature was then used to establish a potential energy surface (PES) diagram along the photodissociation reaction coordinate. The resulting energetics–function model reveals the rate-limiting process to be the transition from the electronic excited-state to the ground-state PES accompanying cis-trans isomerization. Comparisons between split GFPs and other photosensory proteins, like photoactive yellow protein and rhodopsin, provide potential strategies for improving the photodissociation quantum yield.

scholarly journals Competition NMR for Detection of Hit/Lead Inhibitors of Protein–Protein Interactions

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3017 ◽  
Author(s):  
Bogdan Musielak ◽  
Weronika Janczyk ◽  
Ismael Rodriguez ◽  
Jacek Plewka ◽  
Dominik Sala ◽  
...  
Keyword(s):  
Small Molecule ◽  
Protein Interactions ◽  
Point Mutations ◽  
Protein Protein Interactions ◽  
Competition Assay ◽  
Fragment Screening ◽  
Different Types ◽  
Lead Inhibitors

Screening for small-molecule fragments that can lead to potent inhibitors of protein–protein interactions (PPIs) is often a laborious step as the fragments cannot dissociate the targeted PPI due to their low μM–mM affinities. Here, we describe an NMR competition assay called w-AIDA-NMR (weak-antagonist induced dissociation assay-NMR), which is sensitive to weak μM–mM ligand–protein interactions and which can be used in initial fragment screening campaigns. By introducing point mutations in the complex’s protein that is not targeted by the inhibitor, we lower the effective affinity of the complex, allowing for short fragments to dissociate the complex. We illustrate the method with the compounds that block the Mdm2/X-p53 and PD-1/PD-L1 oncogenic interactions. Targeting the PD-/PD-L1 PPI has profoundly advanced the treatment of different types of cancers.

scholarly journals Crystal Structure of SEDL and Its Implications for a Genetic Disease Spondyloepiphyseal Dysplasia Tarda

2002 ◽  
Vol 277 (51) ◽  
pp. 49863-49869 ◽  
Author(s):  
Se Bok Jang ◽  
Yeon-Gil Kim ◽  
Yong-Soon Cho ◽  
Pann-Ghill Suh ◽  
Kyung-Hwa Kim ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Genetic Disease ◽  
Point Mutations ◽  
Missense Mutations ◽  
Protein Protein Interactions ◽  
Spondyloepiphyseal Dysplasia ◽  
Multiple Protein ◽  
Protein Particle ◽  
Eukaryotic Organisms ◽  
Spondyloepiphyseal Dysplasia Tarda

SEDL is an evolutionarily highly conserved protein in eukaryotic organisms. Deletions or point mutations in theSEDLgene are responsible for the genetic disease spondyloepiphyseal dysplasia tarda (SEDT), an X-linked skeletal disorder. SEDL has been identified as a component of the transport protein particle (TRAPP), critically involved in endoplasmic reticulum-to-Golgi vesicle transport. Herein, we report the 2.4 Å resolution structure of SEDL, which reveals an unexpected similarity to the structures of the N-terminal regulatory domain of two SNAREs, Ykt6p and Sec22b, despite no sequence homology to these proteins. The similarity and the presence of unusually many solvent-exposed apolar residues of SEDL suggest that it serves regulatory and/or adaptor functions through multiple protein-protein interactions. Of the four known missense mutations responsible for SEDT, three mutations (S73L, F83S, V130D) map to the protein interior, where the mutations would disrupt the structure, and the fourth (D47Y) on a surface at which the mutation may abrogate functional interactions with a partner protein.

scholarly journals Decreased Interactions between Calmodulin and a Mutant Huntingtin Model Might Reduce the Cytotoxic Level of Intracellular Ca2+: A Molecular Dynamics Study

2021 ◽  
Vol 22 (16) ◽  
pp. 9025
Author(s):  
Sanda Nastasia Moldovean ◽  
Vasile Chiş
Keyword(s):  
Molecular Dynamics ◽  
Protein Interactions ◽  
Structural Changes ◽  
Binding Free Energy ◽  
Point Mutations ◽  
Antagonistic Effect ◽  
Free Energy Calculations ◽  
Point Of View ◽  
Mutant Huntingtin ◽  
Protein Protein Interactions

Mutant huntingtin (m-HTT) proteins and calmodulin (CaM) co-localize in the cerebral cortex with significant effects on the intracellular calcium levels by altering the specific calcium-mediated signals. Furthermore, the mutant huntingtin proteins show great affinity for CaM that can lead to a further stabilization of the mutant huntingtin aggregates. In this context, the present study focuses on describing the interactions between CaM and two huntingtin mutants from a biophysical point of view, by using classical Molecular Dynamics techniques. The huntingtin models consist of a wild-type structure, one mutant with 45 glutamine residues and the second mutant with nine additional key-point mutations from glutamine residues into proline residues (9P(EM) model). Our docking scores and binding free energy calculations show higher binding affinities of all HTT models for the C-lobe end of the CaM protein. In terms of dynamic evolution, the 9P(EM) model triggered great structural changes into the CaM protein’s structure and shows the highest fluctuation rates due to its structural transitions at the helical level from α-helices to turns and random coils. Moreover, our proposed 9P(EM) model suggests much lower interaction energies when compared to the 45Qs-HTT mutant model, this finding being in good agreement with the 9P(EM)’s antagonistic effect hypothesis on highly toxic protein–protein interactions.

scholarly journals Mutation effect estimation on protein–protein interactions using deep contextualized representation learning

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Guangyu Zhou ◽  
Muhao Chen ◽  
Chelsea J T Ju ◽  
Zheng Wang ◽  
Jyun-Yu Jiang ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Protein Pair ◽  
Expert Knowledge ◽  
State Of The Art ◽  
Point Mutations ◽  
Representation Learning ◽  
Structural Features ◽  
Sequence Information ◽  
Protein Protein Interactions ◽  
Subtle Change

Abstract The functional impact of protein mutations is reflected on the alteration of conformation and thermodynamics of protein–protein interactions (PPIs). Quantifying the changes of two interacting proteins upon mutations is commonly carried out by computational approaches. Hence, extensive research efforts have been put to the extraction of energetic or structural features on proteins, followed by statistical learning methods to estimate the effects of mutations on PPI properties. Nonetheless, such features require extensive human labors and expert knowledge to obtain, and have limited abilities to reflect point mutations. We present an end-to-end deep learning framework, MuPIPR (Mutation Effects in Protein–protein Interaction PRediction Using Contextualized Representations), to estimate the effects of mutations on PPIs. MuPIPR incorporates a contextualized representation mechanism of amino acids to propagate the effects of a point mutation to surrounding amino acid representations, therefore amplifying the subtle change in a long protein sequence. On top of that, MuPIPR leverages a Siamese residual recurrent convolutional neural encoder to encode a wild-type protein pair and its mutation pair. Multi-layer perceptron regressors are applied to the protein pair representations to predict the quantifiable changes of PPI properties upon mutations. Experimental evaluations show that, with only sequence information, MuPIPR outperforms various state-of-the-art systems on estimating the changes of binding affinity for SKEMPI v1, and offers comparable performance on SKEMPI v2. Meanwhile, MuPIPR also demonstrates state-of-the-art performance on estimating the changes of buried surface areas. The software implementation is available at https://github.com/guangyu-zhou/MuPIPR.

scholarly journals BIRC3 and BIRC5: multi‐faceted inhibitors in cancer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Raffaele Frazzi
Keyword(s):  
Cancer Cells ◽  
Protein Interactions ◽  
Point Mutations ◽  
Therapeutic Targets ◽  
Progression Free Survival ◽  
Lymphocytic Leukemia ◽  
Low Grade ◽  
Main Body ◽  
Protein Protein Interactions ◽  
Smac Mimetics

Abstract Background The evasion from apoptosis is a common strategy adopted by most tumors, and inhibitors of apoptosis proteins (IAPs) are among the most studied molecular and therapeutic targets. BIRC3 (cellular IAP2) and BIRC5 (survivin) are two of the eight members of the human IAPs family. This family is characterized by the presence of the baculoviral IAP repeat (BIR) domains, involved in protein-protein interactions. In addition to the BIR domains, IAPs also contain other important domains like the C-terminal ubiquitin-conjugating (UBC) domain, the caspase recruitment (CARD) domain and the C-terminal Ring zinc-finger (RING) domain. Main body BIRC3 and BIRC5 have been characterized in some solid and hematological tumors and are therapeutic targets for the family of drugs called “Smac mimetics”. Many evidences point to the pro-survival and antiapoptotic role of BIRC3 in cancer cells, however, not all the data are consistent and the resulting picture is heterogeneous. For instance, BIRC3 genetic inactivation due to deletions or point mutations is consistently associated to shorter progression free survival and poor prognosis in chronic lymphocytic leukemia patients. BIRC3 inactivation has also been associated to chemoimmunotherapy resistance. On the contrary, the progression from low grade gliomas to high grade gliomas is accompanied by BIRC3 expression increase, which bears relevant prognostic consequences. Due to the relationship between BIRC3, MAP3K14 and the non-canonical NF-kB pathway, BIRC3 inactivation bears consequences also on the tumor cells relying on NF-kB pathway to survive. BIRC5, on the contrary, is commonly considered an anti-apoptotic molecule, promoting cell division and tumor progression and it is widely regarded as potential therapeutic target. Conclusions The present manuscript collects and reviews the most recent literature concerning the role played by BIRC3 and BIRC5 in cancer cells, providing useful information for the choice of the best therapeutic targets.

scholarly journals Designer protein assemblies with tunable phase diagrams in living cells

2020 ◽  
Author(s):  
Meta Heidenreich ◽  
Joseph M. Georgeson ◽  
Emanuele Locatelli ◽  
Lorenzo Rovigatti ◽  
Saroj Kumar Nandi ◽  
...  
Keyword(s):  
Phase Diagrams ◽  
Protein Interactions ◽  
Self Assembly ◽  
Point Mutations ◽  
Living Cells ◽  
Protein Protein Interactions ◽  
Material State ◽  
Protein Components ◽  
Novel Strategy

AbstractThe self-organization of proteins into specific assemblies is a hallmark of biological systems. Principles governing protein-protein interactions have long been known. However, principles by which such nanoscale interactions generate diverse phenotypes of mesoscale assemblies, including phase-separated compartments, remains challenging to characterize and understand. To illuminate such principles, we create a system of two proteins designed to interact and form mesh-like assemblies in living cells. We devise a novel strategy to map high-resolution phase diagrams in vivo, which provide mesoscale self-assembly signatures of our system. The structural modularity of the two protein components allows straightforward modification of their molecular properties, enabling us to characterize how point mutations that change their interaction affinity impact the phase diagram and material state of the assemblies in vivo. Both, the phase diagrams and their dependence on interaction affinity were captured by theory and simulations, including out-of-equilibrium effects seen in growing cells. Applying our system to interrogate biological mechanisms of self-assembly, we find that co-translational protein binding suffices to recruit an mRNA to the designed micron-scale structures.

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