Mechanistic Insights into the Inhibition of a Common CTLA-4 Gene Mutation in the Cytoplasmic Domain.

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a pivotal immune checkpoint receptor, playing a crucial role in modulating T-cell activation. In this study, we delved into the underlying mechanism by which a common mutation, G199R, in the cytoplasmic domain of CTLA-4 impacts its inhibitory function. Utilizing nuclear magnetic resonance (NMR) spectroscopy and biochemical techniques, we mapped the conformational changes induced by this mutation and investigated its role in CTLA-4 activity.

Lipidomics analysis of rice bran during storage unveils mechanisms behind dynamic changes in functional lipid molecular species.

Rice bran, recognized for its rich lipids and health-beneficial bioactive compounds, holds considerable promise in applications such as rice bran oil production. However, its susceptibility to lipid hydrolysis and oxidation during storage presents a significant challenge. In response, we conducted an in-depth metabolic profiling of rice bran over a storage period of 14 days.

Deciphering Cholesterol's Role in PD-L2 Stability: A Distinct Regulatory Mechanism From PD-L1.

Programmed cell death 1 ligand 2 (PD-L2), a member of the B7 immune checkpoint protein family, emerges as a crucial player in immune modulation. Despite its functional overlap with programmed cell death 1 ligand 1 (PD-L1) in binding to the programmed cell death protein 1 (PD-1) on T cells, PD-L2 exhibits a divergent expression pattern and a higher affinity for PD-1. However, the regulatory mechanisms of PD-L2 remain under-explored.

Identification of a novel class of cyclic penta-peptides against hepatitis C virus as p7 channel blockers.

The hepatitis C virus (HCV) p7 viroporin protein is essential for viral assembly and release, suggesting its unrealised potential as a target for HCV interventions. Several classes of small molecules that can inhibit p7 through allosteric mechanisms have shown low efficacy. Here, we used a high throughput virtual screen to design a panel of eight novel cyclic penta-peptides (CPs) that target the p7 channel with high binding affinity.

Experimental Investigations on the Structure of Yeast Mitochondrial Pyruvate Carriers.

Mitochondrial pyruvate carrier (MPC) transports pyruvate from the cytoplasm into the mitochondrial matrix to participate in the tricarboxylic acid (TCA) cycle, which further generates the energy for the physiological activities of cells. Two interacting subunits, MPC1 and MPC2 or MPC3, form a heterodimer to conduct transport function. However, the structural basis of how the MPC complex transports pyruvate is still lacking.

Regulation of PD-L1 through direct binding of cholesterol to CRAC motifs.

Cholesterol, an essential molecule for cell structure, function, and viability, plays crucial roles in the development, progression, and survival of cancer cells. Earlier studies have shown that cholesterol-lowering drugs can inhibit the high expression of programmed-death ligand 1 (PD-L1) that contributes to immunoevasion in cancer cells. However, the regulatory mechanism of cell surface PD-L1 abundance by cholesterol is still controversial.

Specific Effects of Characteristics of Enriched Environment on Innovative Problem Solving by Animals.

Numerous studies have revealed that an enriched environment can enhance the survival-related behaviors and brain functions of animals. However, the effects and specific roles of the enrichment characteristics on animals' innovative capability, a cognitive ability crucial for survival in nature, are still not well known. In this study, we assigned mice to environment-manipulation groups ( = 15 each) to investigate the specific effects of environmental novelty (novel vs.

A meta-analytic study of the effects of early maternal separation on cognitive flexibility in rodent offspring.

Adverse early life experiences, such as maternal separation, are associated with an increased risk for several mental health problems. Symptoms induced by maternal separation that mirror clinically relevant aspects of mental problems, such as cognitive inflexibility, open the possibility of testing putative therapeutics prior to clinical development. Although several animal (e.

NMR Characterization of Long-Chain Fatty Acylcarnitine Binding to the Mitochondrial Carnitine/Acylcarnitine Carrier.

The mitochondrial carnitine/acylcarnitine carrier (CAC) transports short-, medium- and long-carbon chain acylcarnitines across the mitochondrial inner membrane in exchange for carnitine. How CAC recognizes the substrates with various fatty acyl groups, especially long-chain fatty acyl groups, remains unclear. Here, using nuclear magnetic resonance (NMR) technology, we have shown that the CAC protein reconstituted into a micelle system exhibits a typical six transmembrane structure of the mitochondrial carrier family.

Structural characterization of a dimerization interface in the CD28 transmembrane domain.

CD28 has a crucial role in regulating immune responses by enhancing T cell activation and differentiation. Recent studies have shown that the transmembrane helix (TMH) of CD28 mediates receptor assembly and activity, but a structural characterization of TMH is still lacking. Here, we determined the dimeric helix-helix packing of CD28-TMH using nuclear magnetic resonance (NMR) technology.

NMR Detection and Structural Modeling of the Ethylene Receptor LeETR2 from Tomato.

The gaseous plant hormone ethylene influences many physiological processes in plant growth and development. Plant ethylene responses are mediated by a family of ethylene receptors, in which the N-terminal transmembrane domains are responsible for ethylene binding and membrane localization. Until now, little structural information was available on the molecular mechanism of ethylene responses by the transmembrane binding domain of ethylene receptors.

Ni Catalyzed Cleavage of TrpLE-Fused Small Transmembrane Peptides.

In addition to a membrane anchor, the transmembrane domain (TMD) of single-pass transmembrane proteins (SPTMPs) recently has shown essential roles in the cross-membrane activity or receptor assembly/clustering. However, these small TMD peptides are generally hydrophobic and dynamic, difficult to be expressed and purified. Here, we have integrated the power of TrpLE fusion protein and a sequence-specific nickel-assisted cleavage (SNAC)-tag to produce small TMD peptides in a highly efficient way under mild conditions, which uses Ni as the cleavage reagent, avoiding the usage of toxic cyanogen bromide (CNBr).

Cholesterol Binds in a Reversed Orientation to TCRβ-TM in Which Its OH Group is Localized to the Center of the Lipid Bilayer.

T cell receptor (TCR) signaling in response to antigen recognition is essential for the adaptive immune response. Cholesterol keeps TCRs in the resting conformation and mediates TCR clustering by directly binding to the transmembrane domain of the TCRβ subunit (TCRβ-TM), while cholesterol sulfate (CS) displaces cholesterol from TCRβ. However, the atomic interaction of cholesterol or CS with TCRβ remains elusive.

Positive Charges in the Brace Region Facilitate the Membrane Disruption of MLKL-NTR in Necroptosis.

Necroptosis is a type of programmed cell death executed through the plasma membrane disruption by mixed lineage kinase domain-like protein (MLKL). Previous studies have revealed that an N-terminal four-helix bundle domain (NBD) of MLKL is the executioner domain for the membrane permeabilization, which is auto-inhibited by the first brace helix (H6). After necroptosis initiation, this inhibitory brace helix detaches and the NBD can integrate into the membrane, and hence leads to necroptotic cell death.

PD-L1 degradation is regulated by electrostatic membrane association of its cytoplasmic domain.

The cytoplasmic domain of PD-L1 (PD-L1-CD) regulates PD-L1 degradation and stability through various mechanism, making it an attractive target for blocking PD-L1-related cancer signaling. Here, by using NMR and biochemical techniques we find that the membrane association of PD-L1-CD is mediated by electrostatic interactions between acidic phospholipids and basic residues in the N-terminal region. The absence of the acidic phospholipids and replacement of the basic residues with acidic residues abolish the membrane association.

An amphipathic Bax core dimer forms part of the apoptotic pore wall in the mitochondrial␣membrane.

Bax proteins form pores in the mitochondrial outer membrane to initiate apoptosis. This might involve their embedding in the cytosolic leaflet of the lipid bilayer, thus generating tension to induce a lipid pore with radially arranged lipids forming the wall. Alternatively, Bax proteins might comprise part of the pore wall.

Multiobjective heuristic algorithm for protein design in a quantified continuous sequence space.

Protein design usually involves sequence search process and evaluation criteria. Commonly used methods primarily implement the Monte Carlo or simulated annealing algorithm with a single-energy function to obtain ideal solutions, which is often highly time-consuming and limited by the accuracy of the energy function. In this report, we introduce a multiobjective algorithm named Hydra for protein design, which employs two different energy functions to optimize solutions simultaneously and makes use of the latent quantitative relationship between different amino acid types to facilitate the search process.

Inhibitor Development against p7 Channel in Hepatitis C Virus.

Hepatitis C Virus (HCV) is the key cause of chronic and severe liver diseases. The recent direct-acting antiviral agents have shown the clinical success on HCV-related diseases, but the rapid HCV mutations of the virus highlight the sustaining necessity to develop new drugs. p7, the viroporin protein from HCV, has been sought after as a potential anti-HCV drug target.

Direct Regulation of the T Cell Antigen Receptor's Activity by Cholesterol.

Biological membranes consist of hundreds of different lipids that together with the embedded transmembrane (TM) proteins organize themselves into small nanodomains. In addition to this function of lipids, TM regions of proteins bind to lipids in a very specific manner, but the function of these TM region-lipid interactions is mostly unknown. In this review, we focus on the role of plasma membrane cholesterol, which directly binds to the αβ T cell antigen receptor (TCR), and has at least two opposing functions in αβ TCR activation.

Expression, purification and characterization of TMCO1 for structural studies.

Transmembrane and coiled-coil domains 1 (TMCO1) has a highly conserved amino acid sequence among species, indicating a critical role of TMCO1 in cell physiology. The deficiency of TMCO1 in humans is associated with cerebrofaciothoracic dysplasia (CFTD), glaucoma, osteogenesis and the occurrence of cancer. TMCO1 was recently identified as an endoplasmic reticulum (ER) Ca load-activated Ca (CLAC) release channel, which prevents ER Ca overload and maintains calcium homeostasis in the ER.

Structural Characterization of the N-Terminal Domain of the Mitochondrial Calcium Uniporter.

The mitochondrial calcium uniporter (MCU) plays a critical role in mitochondrial calcium uptake into the matrix. In metazoans, the uniporter is a tightly regulated multicomponent system, including the pore-forming subunit MCU and several regulators (MICU1, MICU2, and Essential MCU REgulator, EMRE). The calcium-conducting activity of metazoan MCU requires the single-transmembrane protein EMRE.

Gastrodin combined with rhynchophylline inhibits cerebral ischaemia-induced inflammasome activation via upregulating miR-21-5p and miR-331-5p.

Background: The protective effects of gastrodin and rhynchophylline in ischaemic injury have been reported. However, the underlying mechanism and the effect of the combination of these two drugs in ischaemic injury remain unclear. Herein, we aimed to explore the effects of the combination of gastrodin and rhynchophylline on ischaemia-induced inflammasome activation as well as the underlying mechanism.

Critical Effect of the Detergent:Protein Ratio on the Formation of the Hepatitis C Virus p7 Channel.

The p7 protein encoded by the hepatitis C virus forms a cation-selective viroporin in the membrane. One of the most intriguing findings about the p7 viroporin is its unique hexameric structure in dodecylphosphocholine (DPC) micelles determined by nuclear magnetic resonance (NMR), but the hexameric structure was recently challenged by another NMR study of p7, also in DPC detergent, which claimed that the p7 in this detergent is monomeric. Here, we show that p7 oligomerization is highly sensitive to the detergent:protein ratio used in protein reconstitution and that the 40-fold difference in this ratio between the two studies was the cause of their different conclusions.

Specific Interaction of the Human Mitochondrial Uncoupling Protein 1 with Free Long-Chain Fatty Acid.

The mitochondrial uncoupling protein 1 (UCP1) generates heat by causing proton leak across the mitochondrial inner membrane that requires fatty acid (FA). The mechanism by which UCP1 uses FA to conduct proton remains unsolved, and it is also unclear whether a direct physical interaction between UCP1 and FA exists. Here, we have shown using nuclear magnetic resonance that FA can directly bind UCP1 at a helix-helix interface site composed of residues from the transmembrane helices H1 and H6.