Signal transducer gp130: biochemical characterization of the three membrane-proximal extracellular domains and evaluation of their oligomerization potential

2001 ◽  
Vol 356 (2) ◽  
pp. 605-612 ◽  
Author(s):  
Stefan PFLANZ ◽  
Thomas KERNEBECK ◽  
Bernd GIESE ◽  
Andreas HERRMANN ◽  
Michael PACHTA-NICK ◽  
...  
Keyword(s):  
Tertiary Structure ◽  
Biochemical Characterization ◽  
Transmembrane Protein ◽  
Proximal Part ◽  
Cd Spectroscopy ◽  
Size Exclusion ◽  
Type I ◽  
Proximal Half ◽  
Functional Features

Glycoprotein 130 (gp130) is a type I transmembrane protein and serves as the common signal-transducing receptor subunit of the interleukin-6-type cytokines. Whereas the membrane-distal half of the gp130 extracellular part confers ligand binding and has been subject to intense investigation, the structural and functional features of its membrane-proximal half are poorly understood. On the basis of predictions of tertiary structure, the membrane-proximal part consists of three fibronectin-type-III-like domains D4, D5 and D6. Here we describe the bacterial expression of the polypeptides predicted to comprise each of these three domains. The recombinant proteins were refolded from solubilized inclusion bodies in vitro, purified to homogeneity and characterized by means of size-exclusion chromatography and CD spectroscopy. For the first time the prediction of three individual membrane-proximal protein domains for gp130has been verified experimentally. The three domains do not show intermediate-affinity or high-affinity interactions between each other. Mapping of a neutralizing gp130 monoclonal antibody against D4 suggested a particular functional role of this domain for gp130 activation, because above that an intrinsic tendency for low-affinity oligomerization was demonstrated for D4.

scholarly journals LeuRS can leucylate type I and type II tRNALeus in Streptomyces coelicolor

2019 ◽  
Vol 47 (12) ◽  
pp. 6369-6385
Author(s):  
Jia-Yi Fan ◽  
Qian Huang ◽  
Quan-Quan Ji ◽  
En-Duo Wang
Keyword(s):  
Tertiary Structure ◽  
Streptomyces Coelicolor ◽  
Catalytic Efficiency ◽  
Type I ◽  
Type Ii ◽  
Specific Domain ◽  
Recognition Mechanism ◽  
Variable Loop

Abstract Transfer RNAs (tRNAs) are divided into two types, type I with a short variable loop and type II with a long variable loop. Aminoacylation of type I or type II tRNALeu is catalyzed by their cognate leucyl-tRNA synthetases (LeuRSs). However, in Streptomyces coelicolor, there are two types of tRNALeu and only one LeuRS (ScoLeuRS). We found that the enzyme could leucylate both types of ScotRNALeu, and had a higher catalytic efficiency for type II ScotRNALeu(UAA) than for type I ScotRNALeu(CAA). The results from tRNA and enzyme mutagenesis showed that ScoLeuRS did not interact with the canonical discriminator A73. The number of nucleotides, rather than the type of base of the variable loop in the two types of ScotRNALeus, was determined as important for aminoacylation. In vitro and in vivo assays showed that the tertiary structure formed by the D-loop and TψC-loop is more important for ScotRNALeu(UAA). We showed that the leucine-specific domain (LSD) of ScoLeuRS could help LeuRS, which originally only leucylates type II tRNALeu, to aminoacylate type I ScotRNALeu(CAA) and identified the crucial amino acid residues at the C-terminus of the LSD to recognize type I ScotRNALeu(CAA). Overall, our findings identified a rare recognition mechanism of LeuRS to tRNALeu.

scholarly journals Design, Synthesis and Biological Evaluation of (2′,5′ and 3′5′-Linked) cGAMP Analogs that Activate Stimulator of Interferon Genes (STING)

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5285
Author(s):  
Xin Xie ◽  
Junyi Liu ◽  
Xiaowei Wang
Keyword(s):  
Transmembrane Protein ◽  
Biological Evaluation ◽  
Type I ◽  
Vaccine Adjuvants ◽  
One Pot ◽  
Design Synthesis ◽  
Cellular Assays ◽  
Type I Ifns ◽  
Sting Pathway

Stimulator of interferon genes (STING) is an endoplasmic reticulum adaptor transmembrane protein that plays a pivotal role in innate immune system. STING agonists, such as endogenous cyclic dinucleotide (CDN) cyclic GMP-AMP (cGAMP), have been used in diverse clinical research for immunogenic tumor clearance, antiviral treatments and vaccine adjuvants. CDNs containing noncanonical mixed 3′-5′ and 2′-5′ phosphodiester linkages show higher potency in the activation of the STING pathway. In this study, a series of 2′3′-CDNs were designed and synthesized through a modified one-pot strategy. We then established a surface plasmon resonance (SPR)-based binding assay to quantify the binding affinities of synthesized CDNs for human STING, which requested a minuscule amount of sample without any pretreatment. Using this assay, we identified compound 8d (KD = 0.038 μM), a novel CDN that showed higher binding affinity with hSTING than cGAMP (KD = 0.543 μM). Cellular assays confirmed that 8d could trigger the expression of type I IFNs and other proinflammatory cytokines more robust than cGAMP. 8d also exhibited more resistant than cGAMP to enzymatic cleavage in vitro, indicating the successful improvement in drug availability. These findings provide guidelines for the design and structural optimization of CDNs as STING agonists.

scholarly journals Variants of Escherichia coli Subtilase Cytotoxin Subunits Show Differences in Complex Formation In Vitro

Toxins ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 703 ◽  
Author(s):  
Maike Krause ◽  
Katharina Sessler ◽  
Anna Kaziales ◽  
Richard Grahl ◽  
Sabrina Noettger ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hela Cells ◽  
Analytical Ultracentrifugation ◽  
Cd Spectroscopy ◽  
Size Exclusion ◽  
Titration Calorimetry ◽  
Target Cells ◽  
Binding Behavior ◽  
Subtilase Cytotoxin

The subtilase cytotoxin (SubAB) of Shiga toxin-producing Escherichia coli (STEC) is a member of the AB5 toxin family. In the current study, we analyzed the formation of active homo- and hetero-complexes of SubAB variants in vitro to characterize the mode of assembly of the subunits. Recombinant SubA1-His, SubB1-His, SubA2-2-His, and SubB2-2-His subunits, and His-tag-free SubA2-2 were separately expressed, purified, and biochemically characterized by circular dichroism (CD) spectroscopy, size-exclusion chromatography (SEC), and analytical ultracentrifugation (aUC). To confirm their biological activity, cytotoxicity assays were performed with HeLa cells. The formation of AB5 complexes was investigated with aUC and isothermal titration calorimetry (ITC). Binding of SubAB2-2-His to HeLa cells was characterized with flow cytometry (FACS). Cytotoxicity experiments revealed that the analyzed recombinant subtilase subunits were biochemically functional and capable of intoxicating HeLa cells. Inhibition of cytotoxicity by Brefeldin A demonstrated that the cleavage is specific. All His-tagged subunits, as well as the non-tagged SubA2-2 subunit, showed the expected secondary structural compositions and oligomerization. Whereas SubAB1-His complexes could be reconstituted in solution, and revealed a Kd value of 3.9 ± 0.8 μmol/L in the lower micromolar range, only transient interactions were observed for the subunits of SubAB2-2-His in solution, which did not result in any binding constant when analyzed with ITC. Additional studies on the binding characteristics of SubAB2-2-His on HeLa cells revealed that the formation of transient complexes improved binding to the target cells. Conclusively, we hypothesize that SubAB variants exhibit different characteristics in their binding behavior to their target cells.

A Phase I, Multi-Dose, Dose Escalation Study of SGN-40 (anti-huCD40 mAb) in Patients with Refractory or Recurrent Multiple Myeloma.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2413-2413
Author(s):  
Mohamad A. Hussein ◽  
Ruben Niesvizky ◽  
Nikhil Munshi ◽  
James C. Berenson ◽  
Kenneth C. Anderson ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Phase I ◽  
Dose Escalation ◽  
Transmembrane Protein ◽  
M Protein ◽  
Type I ◽  
Antitumor Effects ◽  
Grade 3 ◽  
Dose Levels

Abstract CD40 is a type I transmembrane protein that upon binding to CD40 ligand regulates important biologic effects in the immune system. CD40 is also highly expressed on hematologic tumors, which has raised interest in the potential for its use as a tumor target for antibody-based cancer therapy. SGN-40 is a humanized monoclonal antibody that selectively binds to human CD40 and induces apoptosis and growth inhibition of a wide variety of B-cell derived cancer cell lines in vitro. Our preclinical work has confirmed the in vitro cytotoxicity of SGN-40 against human multiple myeloma (MM) cells via several mechanisms. These include induction of cytotoxic ligands of TNF superfamily; suppression of IL-6-induced proliferative and anti-apoptotic effects, as well as antibody-dependent cell-mediated cytotoxicity (Tai, et al, Cancer Research64, 2846–2852, April 15, 2004). Since ≥ 90% of MM cells express CD40, targeting CD40 using SGN-40 presents a potential novel treatment strategy. Based on these preclinical data, a phase I study is being conducted to define the toxicity profile, characterize the pharmacokinetics (PK), and evaluate antitumor effects of SGN-40 in patients with refractory or recurrent MM. Four weekly doses ranging from 0.5 to 16 mg/kg are planned to be administered to groups of at least three patients per cohort. Patients will be followed for up to 6 weeks post their last dose. Currently, a total of seven patients have been treated with SGN-40 at dose levels of 0.5 and 1.0 mg/kg. No grade 3 or 4 non-hematologic dose limiting toxicities have been observed. One patient experienced a transient Grade 3 decrease in hemoglobin. Decrease in CD19 positive B-cells were noted for patients treated at both dose levels. Changes in serum and urine M protein levels were measured to estimate potential anti-tumor effects of SGN-40. Of the seven patients evaluated, one patient at 0.5 mg/kg dose had stable disease, based on serum M protein, over the 10 week study period. Clinical evaluation with dose escalation of this agent continues and updated safety, PK and antitumor data will be presented.

scholarly journals Interaction of the Amino-Terminal Domain of the ISAV Fusion Protein with a Cognate Cell Receptor

Pathogens ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 416
Author(s):  
Nicolás Ojeda ◽  
Constanza Cárdenas ◽  
Sergio Marshall
Keyword(s):  
Fusion Protein ◽  
Tertiary Structure ◽  
Structural Characteristics ◽  
Cell Receptor ◽  
Type I ◽  
Amino Terminal ◽  
Infectious Salmon Anemia ◽  
Anemia Virus ◽  
Carboxy Terminal

The infectious salmon anemia virus (ISAV), etiological agent of the disease by the same name, causes major losses to the salmon industry. Classified as a member of the Orthomyxoviridae family, ISAV is characterized by the presence of two surface glycoproteins termed hemagglutinin esterase (HE) and fusion protein (F), both of them directly involved in the initial interaction of the virus with the target cell. HE mediates receptor binding and destruction, while F promotes the fusion process of the viral and cell membranes. The carboxy-terminal end of F (F2) possesses canonical structural characteristics of a type I fusion protein, while no functional properties have been proposed for the amino-terminal (F1) region. In this report, based on in silico modeling, we propose a tertiary structure for the F1 region, which resembles a sialic acid binding domain. Furthermore, using recombinant forms of both HE and F proteins and an in vitro model system, we demonstrate the interaction of F with a cell receptor, the hydrolysis of this receptor by the HE esterase, and a crucial role for F1 in the fusion mechanism. Our interpretation is that binding of F to its cell receptor is fundamental for membrane fusion and that the esterase in HE modulates this interaction.

scholarly journals Fusion Potential of Human Osteoclasts In Vitro Reflects Age, Menopause, and In Vivo Bone Resorption Levels of Their Donors—A Possible Involvement of DC-STAMP

2020 ◽  
Vol 21 (17) ◽  
pp. 6368
Author(s):  
Anaïs M. J. Møller ◽  
Jean-Marie Delaissé ◽  
Jacob B. Olesen ◽  
Luisa M. Canto ◽  
Silvia R. Rogatto ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Type I Collagen ◽  
Transmembrane Protein ◽  
Type I ◽  
Contributing Factors ◽  
Expression Levels ◽  
Procollagen Type ◽  
Age Related

It is well established that multinucleation is central for osteoclastic bone resorption. However, our knowledge on the mechanisms regulating how many nuclei an osteoclast will have is limited. The objective of this study was to investigate donor-related variations in the fusion potential of in vitro-generated osteoclasts. Therefore, CD14+ monocytes were isolated from 49 healthy female donors. Donor demographics were compared to the in vivo bone biomarker levels and their monocytes’ ability to differentiate into osteoclasts, showing that: (1) C-terminal telopeptide of type I collagen (CTX) and procollagen type I N-terminal propeptide (PINP) levels increase with age, (2) the number of nuclei per osteoclast in vitro increases with age, and (3) there is a positive correlation between the number of nuclei per osteoclast in vitro and CTX levels in vivo. Furthermore, the expression levels of the gene encoding dendritic cell-specific transmembrane protein (DCSTAMP) of osteoclasts in vitro correlated positively with the number of nuclei per osteoclast, CTX levels in vivo, and donor age. Our results furthermore suggest that these changes in gene expression may be mediated through age-related changes in DNA methylation levels. We conclude that both intrinsic factors and age-induced increase in fusion potential of osteoclasts could be contributing factors for the enhanced bone resorption in vivo, possibly caused by increased expression levels of DCSTAMP.

scholarly journals Biochemical Characterization and Structural Modeling of Fused Glucose-6-Phosphate Dehydrogenase-Phosphogluconolactonase from Giardia lamblia

2018 ◽  
Vol 19 (9) ◽  
pp. 2518 ◽  
Author(s):  
Laura Morales-Luna ◽  
Hugo Serrano-Posada ◽  
Abigail González-Valdez ◽  
Daniel Ortega-Cuellar ◽  
America Vanoye-Carlo ◽  
...  
Keyword(s):  
Giardia Lamblia ◽  
Tertiary Structure ◽  
Biochemical Characterization ◽  
Guanidine Hydrochloride ◽  
Pentose Phosphate ◽  
New Drugs ◽  
Oligomeric State ◽  
Functional Features ◽  
The Stability ◽  
Glucose 6 Phosphate Dehydrogenase

Glucose-6-phosphate dehydrogenase (G6PD) is the first enzyme in the pentose phosphate pathway and is highly relevant in the metabolism of Giardia lamblia. Previous reports suggested that the G6PD gene is fused with the 6-phosphogluconolactonase (6PGL) gene (6pgl). Therefore, in this work, we decided to characterize the fused G6PD-6PGL protein in Giardia lamblia. First, the gene of g6pd fused with the 6pgl gene (6gpd::6pgl) was isolated from trophozoites of Giardia lamblia and the corresponding G6PD::6PGL protein was overexpressed and purified in Escherichia coli. Then, we characterized the native oligomeric state of the G6PD::6PGL protein in solution and we found a catalytic dimer with an optimum pH of 8.75. Furthermore, we determined the steady-state kinetic parameters for the G6PD domain and measured the thermal stability of the protein in both the presence and absence of guanidine hydrochloride (Gdn-HCl) and observed that the G6PD::6PGL protein showed alterations in the stability, secondary structure, and tertiary structure in the presence of Gdn-HCl. Finally, computer modeling studies revealed unique structural and functional features, which clearly established the differences between G6PD::6PGL protein from G. lamblia and the human G6PD enzyme, proving that the model can be used for the design of new drugs with antigiardiasic activity. These results broaden the perspective for future studies of the function of the protein and its effect on the metabolism of this parasite as a potential pharmacological target.

Screening Tagged Proteins Using Tandem Affinity-Buffer Exchange Chromatography Online with Native Mass Spectrometry

2021 ◽  
Author(s):  
Florian Busch ◽  
Zachary VanAernum ◽  
Stella M. Lai ◽  
Venkat Gopalan ◽  
Vicki Wysocki
Keyword(s):  
Mass Spectrometry ◽  
Large Scale ◽  
Tertiary Structure ◽  
Direct Analysis ◽  
Native Mass Spectrometry ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
Functional Protein ◽  
Translation Rate

Protein overexpression and purification are critical for in vitro structure-function characterization studies. However, some proteins are difficult to express robustly in heterologous systems due to host-related (e.g., codon usage, translation rate) and/or protein specific (e.g., toxicity, aggregation) challenges. Therefore, it is often necessary to screen<br>multiple overexpression and purification conditions to maximize the yield of functional protein, particularly for resource-heavy downstream applications (e.g., biocatalysts, tertiary structure determination, biotherapeutics). Here, we describe an automatable liquid chromatography–mass spectrometry-based method for rapid, direct analysis of target proteins in cell lysates. This online approach is facilitated by coupling immobilized metal affinity chromatography (IMAC), which leverages engineered poly-histidine tags in proteins of interest, with size exclusion-based buffer exchange (OBE) and native mass spectrometry (nMS). The use of IMAC-OBE-nMS to optimize conditions for large-scale protein production should expedite structural biology and biotherapeutic initiatives.<br>

scholarly journals Mannose receptor regulates myoblast motility and muscle growth

2006 ◽  
Vol 174 (3) ◽  
pp. 403-413 ◽  
Author(s):  
Katie M. Jansen ◽  
Grace K. Pavlath
Keyword(s):  
Skeletal Muscle ◽  
Transmembrane Protein ◽  
Muscle Growth ◽  
Mannose Receptor ◽  
Time Lapse ◽  
Myoblast Fusion ◽  
Type I ◽  
Matrix Remodeling

Myoblast fusion is critical for the formation, growth, and maintenance of skeletal muscle. The initial formation of nascent myotubes requires myoblast–myoblast fusion, but further growth involves myoblast–myotube fusion. We demonstrate that the mannose receptor (MR), a type I transmembrane protein, is required for myoblast–myotube fusion. Mannose receptor (MR)–null myotubes were small in size and contained a decreased myonuclear number both in vitro and in vivo. We hypothesized that this defect may arise from a possible role of MR in cell migration. Time-lapse microscopy revealed that MR-null myoblasts migrated with decreased velocity during myotube growth and were unable to migrate in a directed manner up a chemoattractant gradient. Furthermore, collagen uptake was impaired in MR-null myoblasts, suggesting a role in extracellular matrix remodeling during cell motility. These data identify a novel function for MR during skeletal muscle growth and suggest that myoblast motility may be a key aspect of regulating myotube growth.

scholarly journals New isolation procedure and further biochemical characterization of glycoproteins IIb and IIIa from human platelet plasma membrane

1986 ◽  
Vol 240 (1) ◽  
pp. 147-153 ◽  
Author(s):  
M T Eirín ◽  
J J Calvete ◽  
J González-Rodríguez
Keyword(s):  
Plasma Membrane ◽  
High Performance ◽  
Tertiary Structure ◽  
Biochemical Characterization ◽  
Human Platelet ◽  
Sugar Content ◽  
Size Exclusion ◽  
Apparent Lack ◽  
Weight Percentage ◽  
Triton X

We describe a new procedure for isolation of glycoproteins IIb (GPIIb) and IIIa (GPIIIa) from human platelet plasma membrane with high yields (2.7 mg of GPIIb and 3.3 mg of GPIIIa per 100 mg of starting platelet membrane proteins), equivalent to a recovery of 35% and 55% respectively of the total GPIIb and GPIIIa of the membrane. The procedure involves Triton X-100 differential extraction of platelet membranes, SDS solubilization of the 4%-Triton X-100 supernatant, zonal centrifugation in a sucrose density gradient, and preparative high-performance size-exclusion chromatography. The weight percentage of sugar is 15.7% for GPIIb and 12.5% for GPIIIa. Neuraminic acid is present in both glycoproteins, representing 30% and 15% respectively of the total sugar weight of GPIIb and GPIIIa. Mannose, galactose and glucosamine account for 45%, 13% and 28% respectively of the sugars of GPIIIa, whereas galactosamine was not detected. Mannose, galactose, glucosamine and galactosamine represent 17%, 21%, 24% and 10% respectively of the sugar content of GPIIb. The molar percentages of half-cystine and methionine are 4-fold and 2-fold higher respectively in GPIIIa than in GPIIb. From the amino acid and sugar compositions we confirmed the acidic nature of both glycoproteins. The Mr values obtained, 136,500 for GPIIb and 91,500 for GPIIIa, are in very good agreement with those obtained by physical methods. The apparent lack of free thiol groups in both glycoproteins indicates that the tertiary structure of GPIIIa is maintained by 21 intrachain disulphide bonds, and that there are eight intrachain and interchain disulphide groups in GPIIb.

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