scholarly journals Mechanism of p38 MAPK–induced EGFR endocytosis and its crosstalk with ligand-induced pathways

2021 ◽  
Vol 220 (7) ◽  
Author(s):  
Mireia Perez Verdaguer ◽  
Tian Zhang ◽  
Joao A. Paulo ◽  
Steven Gygi ◽  
Simon C. Watkins ◽  
...  
Keyword(s):  
Ligand Binding ◽  
P38 Mapk ◽  
Ph Sensitive ◽  
Receptor Internalization ◽  
Dileucine Motif ◽  
Ligand Free ◽  
Clathrin Adaptor ◽  
High Ligand

Ligand binding triggers clathrin-mediated and, at high ligand concentrations, clathrin-independent endocytosis of EGFR. Clathrin-mediated endocytosis (CME) of EGFR is also induced by stimuli activating p38 MAPK. Mechanisms of both ligand- and p38-induced endocytosis are not fully understood, and how these pathways intermingle when concurrently activated remains unknown. Here we dissect the mechanisms of p38-induced endocytosis using a pH-sensitive model of endogenous EGFR, which is extracellularly tagged with a fluorogen-activating protein, and propose a unifying model of the crosstalk between multiple EGFR endocytosis pathways. We found that a new locus of p38-dependent phosphorylation in EGFR is essential for the receptor dileucine motif interaction with the σ2 subunit of clathrin adaptor AP2 and concomitant receptor internalization. p38-dependent endocytosis of EGFR induced by cytokines was additive to CME induced by picomolar EGF concentrations but constrained to internalizing ligand-free EGFRs due to Grb2 recruitment by ligand-activated EGFRs. Nanomolar EGF concentrations rerouted EGFR from CME to clathrin-independent endocytosis, primarily by diminishing p38-dependent endocytosis.

CarR, a MarR-family regulator from Corynebacterium glutamicum, modulated antibiotic and aromatic compound resistance

2019 ◽  
Vol 476 (21) ◽  
pp. 3141-3159 ◽  
Author(s):  
Meiru Si ◽  
Can Chen ◽  
Zengfan Wei ◽  
Zhijin Gong ◽  
GuiZhi Li ◽  
...  
Keyword(s):  
Stress Response ◽  
Ligand Binding ◽  
Corynebacterium Glutamicum ◽  
Conformational Changes ◽  
Cysteine Oxidation ◽  
Transcriptional Regulatory ◽  
Ligand Free ◽  
Redox Sensing

Abstract MarR (multiple antibiotic resistance regulator) proteins are a family of transcriptional regulators that is prevalent in Corynebacterium glutamicum. Understanding the physiological and biochemical function of MarR homologs in C. glutamicum has focused on cysteine oxidation-based redox-sensing and substrate metabolism-involving regulators. In this study, we characterized the stress-related ligand-binding functions of the C. glutamicum MarR-type regulator CarR (C. glutamicum antibiotic-responding regulator). We demonstrate that CarR negatively regulates the expression of the carR (ncgl2886)–uspA (ncgl2887) operon and the adjacent, oppositely oriented gene ncgl2885, encoding the hypothetical deacylase DecE. We also show that CarR directly activates transcription of the ncgl2882–ncgl2884 operon, encoding the peptidoglycan synthesis operon (PSO) located upstream of carR in the opposite orientation. The addition of stress-associated ligands such as penicillin and streptomycin induced carR, uspA, decE, and PSO expression in vivo, as well as attenuated binding of CarR to operator DNA in vitro. Importantly, stress response-induced up-regulation of carR, uspA, and PSO gene expression correlated with cell resistance to β-lactam antibiotics and aromatic compounds. Six highly conserved residues in CarR were found to strongly influence its ligand binding and transcriptional regulatory properties. Collectively, the results indicate that the ligand binding of CarR induces its dissociation from the carR–uspA promoter to derepress carR and uspA transcription. Ligand-free CarR also activates PSO expression, which in turn contributes to C. glutamicum stress resistance. The outcomes indicate that the stress response mechanism of CarR in C. glutamicum occurs via ligand-induced conformational changes to the protein, not via cysteine oxidation-based thiol modifications.

scholarly journals Protein-ligand free energies of binding from full-protein DFT calculations: convergence and choice of exchange-correlation functional

2021 ◽  
Author(s):  
Lennart Gundelach ◽  
Christofer S Tautermann ◽  
Thomas Fox ◽  
Chris-Kriton Skylaris
Keyword(s):  
Drug Discovery ◽  
Ligand Binding ◽  
Dft Calculations ◽  
Quantum Mechanical ◽  
Free Energies ◽  
Ligand Interaction ◽  
Exchange Correlation ◽  
Ligand Free ◽  
Protein Ligand Interaction ◽  
Binding Free Energies

The accurate prediction of protein-ligand binding free energies with tractable computational methods has the potential to revolutionize drug discovery. Modeling the protein-ligand interaction at a quantum mechanical level, instead of...

scholarly journals A dileucine motif in the C terminus of the  2-adrenergic receptor is involved in receptor internalization

1997 ◽  
Vol 94 (23) ◽  
pp. 12285-12290 ◽  
Author(s):  
A. M. Gabilondo ◽  
J. Hegler ◽  
C. Krasel ◽  
V. Boivin-Jahns ◽  
L. Hein ◽  
...  
Keyword(s):  
Adrenergic Receptor ◽  
Receptor Internalization ◽  
C Terminus ◽  
Dileucine Motif

scholarly journals Ligand-induced internalization of the type 1 cholecystokinin receptor independent of recognized signaling activity

2012 ◽  
Vol 302 (3) ◽  
pp. C615-C627 ◽  
Author(s):  
Erin E. Cawston ◽  
Kaleeckal G. Harikumar ◽  
Laurence J. Miller
Keyword(s):  
Ligand Binding ◽  
Competitive Inhibition ◽  
Chinese Hamster ◽  
Receptor Internalization ◽  
Ovary Cell ◽  
Receptor Ligands ◽  
Cholecystokinin Receptor ◽  
Transmembrane Segments ◽  
Loop Region

Receptor ligands, identified as antagonists, based on the absence of stimulation of signaling, can rarely stimulate receptor internalization. d-Tyr-Gly-[(Nle28,31,d-Trp30)CCK-26–32]-2-phenylethyl ester (d-Trp-OPE) is such a ligand that binds to the cholecystokinin (CCK) receptor and stimulates internalization. Here, the molecular basis of this trafficking event is explored, with the assumption that ligand binding initiates conformational change, exposing an epitope to direct endocytosis. Ligand-stimulated internalization was studied morphologically using fluorescent CCK and d-Trp-OPE. d-Trp-OPE occupation of Chinese hamster ovary cell receptors stimulated internalization into the same region as CCK. Arrestin-biased action was ruled out using morphological translocation of fluorescent arrestin 2 and arrestin 3, moving to the membrane in response to CCK, but not d-Trp-OPE. Possible roles of the carboxyl terminus were studied using truncated receptor constructs, eliminating the proline-rich distal tail, the serine/threonine-rich midregion, and the remainder to the vicinal cysteines. None of these constructs disrupted d-Trp-OPE-stimulated internalization. Possible contributions of transmembrane segments were studied using competitive inhibition with peptides that also had no effect. Intracellular regions were studied with a similar strategy using coexpressing cell lines. Peptides corresponding to ends of each loop region were studied, with only the peptide at the carboxyl end of the third loop inhibiting d-Trp-OPE-stimulated internalization but having no effect on CCK-stimulated internalization. The region contributing to this effect was refined to peptide 309–323, located below the recognized G protein-association motif. While a receptor in which this segment was deleted did internalize in response to d-Trp-OPE, it exhibited abnormal ligand binding and did not signal in response to CCK, suggesting an abnormal conformation and possible mechanism of internalization distinct from that being studied. This interpretation was further supported by the inability of peptide 309–323 to inhibit its d-Trp-OPE-stimulated internalization. Thus the 309–323 region of the type 1 CCK receptor affects antagonist-stimulated internalization of this receptor, although its mechanism and interacting partner are not yet clear.

scholarly journals A pH-Sensitive Fluor, CypHerTM 5, Used to Monitor Agonist-Induced G Protein-Coupled Receptor Internalization in Live Cells

BioTechniques ◽  
2002 ◽  
Vol 33 (5) ◽  
pp. 1152-1157 ◽  
Author(s):  
E.J. Adie ◽  
S. Kalinka ◽  
L. Smith ◽  
M.J. Francis ◽  
A. Marenghi ◽  
...  
Keyword(s):  
G Protein ◽  
Ph Sensitive ◽  
Receptor Internalization ◽  
Live Cells ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

scholarly journals Mutation of the important Tyr-33 residue of chicken avidin: functional and structural consequences

2003 ◽  
Vol 369 (2) ◽  
pp. 249-254 ◽  
Author(s):  
Ari T. MARTTILA ◽  
Vesa P. HYTÖNEN ◽  
Olli H. LAITINEN ◽  
Edward A. BAYER ◽  
Meir WILCHEK ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Quaternary Structure ◽  
Affinity Purification ◽  
Ph Dependence ◽  
Tight Binding ◽  
Carbonyl Oxygen ◽  
Binding Characteristics ◽  
Biotin Binding ◽  
High Ligand

The strong interaction between avidin and biotin is so tight (dissociation constant 10-15M) that conditions usually sufficient for protein denaturing fail to dislodge biotin from the avidin—biotin complex. This kind of irreversible binding hinders the use of avidin in applications such as affinity purification or protein immobilization. To address this concern, we have constructed a series of mutants of the strategically positioned Tyr-33 in order to study the role of this residue in biotin binding, and to create avidin variants with more reversible ligand-binding properties. Unexpectedly, an avidin mutant in which Tyr-33 was replaced with phenylalanine (Avm-Y33F) displayed similar biotin-binding characteristics to the native avidin, indicating that the hydrogen bond formed between the hydroxy group of Tyr-33 and the carbonyl oxygen of biotin is not as important for the tight binding of biotin as previously suggested. In terms of the reversibility of biotin binding, Avm-Y33H was the most successful substitution constructed in this study. Interestingly, the binding of this mutant exhibited clear pH-dependence, since at neutral pH it bound to the biotin surface in an irreversible fashion, whereas, at pH9, 50% of the bound protein could be released with free biotin. Furthermore, although Tyr-33 is located relatively distant from the monomer—monomer interfaces, the mutagenesis of this residue also weakened the quaternary structure of avidin, indicating that the high ligand binding and the high stability of avidin have evolved together and it is difficult to modify one without affecting the other.

scholarly journals A Conserved Dileucine Motif Mediates Clathrin and AP-2–dependent Endocytosis of the HIV-1 Envelope Protein

2007 ◽  
Vol 18 (2) ◽  
pp. 414-425 ◽  
Author(s):  
Rahel Byland ◽  
Patricia J. Vance ◽  
James A. Hoxie ◽  
Mark Marsh
Keyword(s):  
Transmembrane Protein ◽  
Viral Envelope ◽  
Membrane Expression ◽  
Dileucine Motif ◽  
Plasma Membrane Expression ◽  
Protein Gp41 ◽  
Clathrin Adaptor ◽  
Cellular Components ◽  
Specific Membrane

During the assembly of enveloped viruses viral and cellular components essential for infectious particles must colocalize at specific membrane locations. For the human and simian immunodeficiency viruses (HIV and SIV), sorting of the viral envelope proteins (Env) to assembly sites is directed by trafficking signals located in the cytoplasmic domain of the transmembrane protein gp41 (TM). A membrane proximal conserved GYxxØ motif mediates endocytosis through interaction with the clathrin adaptor AP-2. However, experiments with SIVmac239Env indicate the presence of additional signals. Here we show that a conserved C-terminal dileucine in HIVHxB2also mediates endocytosis. Biochemical and morphological assays demonstrate that the C-terminal dileucine motif mediates internalization as efficiently as the GYxxØ motif and that both must be removed to prevent Env internalization. RNAi experiments show that depletion of the clathrin adaptor AP-2 leads to increased plasma membrane expression of HIV Env and that this adaptor is required for efficient internalization mediated by both signals. The redundancy of conserved endocytosis signals and the role of the SIVmac239Env GYxxØ motif in SIV pathogenesis, suggest that these motifs have functions in addition to endocytosis, possibly related to Env delivery to the site of viral assembly and/or incorporation into budding virions.

Structural analysis of the choline-binding protein ChoX in a semi-closed and ligand-free conformation

2009 ◽  
Vol 390 (11) ◽  
Author(s):  
Christine Oswald ◽  
Sander H.J. Smits ◽  
Marina Höing ◽  
Erhard Bremer ◽  
Lutz Schmitt
Keyword(s):  
Crystal Structure ◽  
Structural Analysis ◽  
Ligand Binding ◽  
Closed Form ◽  
Binding Site ◽  
Sinorhizobium Meliloti ◽  
Binding Protein ◽  
Ligand Binding Site ◽  
Abc Transport ◽  
Ligand Free

Abstract The periplasmic ligand-binding protein ChoX is part of the ABC transport system ChoVWX that imports choline as a nutrient into the soil bacterium Sinorhizobium meliloti. We have recently reported the crystal structures of ChoX in complex with its ligands choline and acetylcholine and the structure of a fully closed but substrate-free state of ChoX. This latter structure revealed an architecture of the ligand-binding site that is superimposable to the closed, ligand-bound form of ChoX. We report here the crystal structure of ChoX in an unusual, ligand-free conformation that represents a semi-closed form of ChoX. The analysis revealed a subdomain movement in the N-lobe of ChoX. Comparison with the two well-characterized substrate binding proteins, MBP and HisJ, suggests the presence of a similar subdomain in these proteins.

scholarly journals Ubiquitination differentially regulates clathrin-dependent internalization of protease-activated receptor-1

2007 ◽  
Vol 177 (5) ◽  
pp. 905-916 ◽  
Author(s):  
Breann L. Wolfe ◽  
Adriano Marchese ◽  
JoAnn Trejo
Keyword(s):  
G Protein ◽  
Protein Complex ◽  
Adaptor Protein ◽  
Receptor Internalization ◽  
Wild Type ◽  
Endocytic Machinery ◽  
Protease Activated Receptor 1 ◽  
Clathrin Adaptor ◽  
G Protein Coupled ◽  
Type Receptor

Protease-activated receptor-1 (PAR1), a G protein–coupled receptor (GPCR) for thrombin, is irreversibly activated by proteolysis. Consequently, PAR1 trafficking is critical for the fidelity of thrombin signaling. PAR1 displays constitutive and agonist-induced internalization, which are clathrin and dynamin dependent but are independent of arrestins. The clathrin adaptor AP2 (adaptor protein complex-2) is critical for constitutive but not for activated PAR1 internalization. In this study, we show that ubiquitination negatively regulates PAR1 constitutive internalization and specifies a distinct clathrin adaptor requirement for activated receptor internalization. PAR1 is basally ubiquitinated and deubiquitinated after activation. A PAR1 lysineless mutant signaled normally but was not ubiquitinated. Constitutive internalization of ubiquitin (Ub)-deficient PAR1 was markedly increased and inhibited by the fusion of Ub to the cytoplasmic tail. Ub-deficient PAR1 constitutive internalization was AP2 dependent like the wild-type receptor. However, unlike wild-type PAR1, AP2 was required for the internalization of activated Ub-deficient receptor, suggesting that the internalization of ubiquitinated PAR1 requires different endocytic machinery. These studies reveal a novel function for ubiquitination in the regulation of GPCR internalization.

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