scholarly journals Ankyrin binds to the 15th repetitive unit of erythroid and nonerythroid beta-spectrin.

1991 ◽  
Vol 115 (1) ◽  
pp. 267-277 ◽  
Author(s):  
S P Kennedy ◽  
S L Warren ◽  
B G Forget ◽  
J S Morrow
Keyword(s):  
Binding Site ◽  
Binding Capacity ◽  
Repeat Unit ◽  
Expression System ◽  
Membrane Vesicles ◽  
Enzymatic Digestion ◽  
Binding Domain ◽  
Amino Terminal ◽  
Prokaryotic Expression System

Ankyrin mediates the attachment of spectrin to transmembrane integral proteins in both erythroid and nonerythroid cells by binding to the beta-subunit of spectrin. Previous studies using enzymatic digestion, 2-nitro-5-thiocyanobenzoic acid cleavage, and rotary shadowing techniques have placed the spectrin-ankyrin binding site in the COOH-terminal third of beta-spectrin, but the precise site is not known. We have used a glutathione S-transferase prokaryotic expression system to prepare recombinant erythroid and nonerythroid beta-spectrin from cDNA encoding approximately the carboxy-terminal half of these proteins. Recombinant spectrin competed on an equimolar basis with 125I-labeled native spectrin for binding to erythrocyte membrane vesicles (IOVs), and also bound ankyrin in vitro as measured by sedimentation velocity experiments. Although full length beta-spectrin could inhibit all spectrin binding to IOVs, recombinant beta-spectrin encompassing the complete ankyrin binding domain but lacking the amino-terminal half of the molecule failed to inhibit about 25% of the binding capacity of the IOVs, suggesting that the ankyrin-independent spectrin membrane binding site must lie in the amino-terminal half of beta-spectrin. A nested set of shortened recombinants was generated by nuclease digestion of beta-spectrin cDNAs from ankyrin binding constructs. These defined the ankyrin binding domain as encompassing the 15th repeat unit in both erythroid and nonerythroid beta-spectrin, amino acid residues 1,768-1,898 in erythroid beta-spectrin. The ankyrin binding repeat unit is atypical in that it lacks the conserved tryptophan at position 45 (1,811) within the repeat and contains a nonhomologous 43 residue segment in the terminal third of the repeat. It also appears that the first 30 residues of this repeat, which are highly conserved between the erythroid and nonerythroid beta-spectrins, are critical for ankyrin binding activity. We hypothesize that ankyrin binds directly to the nonhomologous segment in the 15th repeat unit of both erythroid and nonerythroid beta-spectrin, but that this sequence must be presented in the context of a properly folded spectrin "repeat unit" structure. Future studies will identify which residues within the repeat unit are essential for activity, and which residues determine the specificity of various spectrins for different forms of ankyrin.

Interference in vimentin assembly in vitro by synthetic peptides derived from the vimentin head domain

1992 ◽  
Vol 101 (3) ◽  
pp. 687-700
Author(s):  
I. Hofmann ◽  
H. Herrmann
Keyword(s):  
Synthetic Peptides ◽  
Genetically Engineered ◽  
Binding Domain ◽  
Binding Assays ◽  
Central Sequence ◽  
Amino Terminal ◽  
Molar Excess ◽  
Drastic Increase ◽  
Head Positions

The importance of the amino-terminal domain (“head”) of type III intermediate filament (IF) proteins in IF assembly has been examined by testing the influence of synthetic peptides representing a highly conserved decameric motif, KSSSYRRIMFGG, located near the amino terminus of vimentin. When added to soluble vimentin subunits this peptide induces, at fourfold molar excess or slightly above, the appearance of short, regular rod-like structures as determined by electron microscopy of negatively stained and rotary-shadowed preparations as well as by viscometry. At higher peptide concentrations large, irregularly shaped aggregates of mostly non-IF structures formed, but this aggregation was reversible by prolonged dialysis against low ionic strength buffer. The aggregating effect of this peptide was highly sequence-specific and was not seen with point-mutated sequences such as RR----TR or with unrelated peptides containing a central diarginine, indicating that it is not simply ionic. When different hexapeptides representing different “head” positions were compared, only the central sequence, SYRRXF, was as effective as the decamer. The addition of peptide during IF assembly did not prevent filament formation, although 50-fold molar excess of peptide resulted in a drastic increase (up to 40 nm) in the width of the filaments, which also appeared less regular, thus reflecting some interference with assembly. In contrast to the effects on soluble vimentin, the decameric peptide did not disturb IFs, indicating that the binding domain is “masked” or stabilized in the filaments. To identify the domain to which the peptide binds, three different binding assays using vimentin fragments and genetically engineered vimentin deletion mutants were employed. The results indicate that the binding domain of the near-amino-terminal peptide is located at the start of the alpha-helical “rod” domain of the protein. Possible mechanisms of interaction of these two portions of vimentin during IF assembly are discussed.

scholarly journals Cell Cycle Localization, Dimerization, and Binding Domain Architecture of the Telomere Protein cPot1

2004 ◽  
Vol 24 (5) ◽  
pp. 2091-2102 ◽  
Author(s):  
Chao Wei ◽  
Carolyn M. Price
Keyword(s):  
Cell Cycle ◽  
Dna Binding ◽  
Binding Site ◽  
Domain Architecture ◽  
Binding Domain ◽  
Binding Motif ◽  
Dna Binding Domain ◽  
Telomere Protein ◽  
Ob Fold

ABSTRACT Pot1 is a single-stranded-DNA-binding protein that recognizes telomeric G-strand DNA. It is essential for telomere capping in Saccharomyces pombe and regulates telomere length in humans. Human Pot1 also interacts with proteins that bind the duplex region of the telomeric tract. Thus, like Cdc13 from S. cerevisiae, Pot 1 may have multiple roles at the telomere. We show here that endogenous chicken Pot1 (cPot1) is present at telomeres during periods of the cell cycle when t loops are thought to be present. Since cPot1 can bind internal loops and directly adjacent DNA-binding sites, it is likely to fully coat and protect both G-strand overhangs and the displaced G strand of a t loop. The minimum binding site of cPot1 is double that of the S. pombe DNA-binding domain. Although cPot can self associate, dimerization is not required for DNA binding and hence does not explain the binding-site duplication. Instead, the DNA-binding domain appears to be extended to contain a second binding motif in addition to the conserved oligonucleotide-oligosaccharide (OB) fold present in other G-strand-binding proteins. This second motif could be another OB fold. Although dimerization is inefficient in vitro, it may be regulated in vivo and could promote association with other telomere proteins and/or telomere compaction.

scholarly journals Development of a Trivalent Construct Omp18/AhpC/FlgH Multi Epitope Peptide Vaccine Against Campylobacter jejuni

2022 ◽  
Vol 12 ◽  
Author(s):  
Hongqiang Lou ◽  
Xusheng Li ◽  
Xiusheng Sheng ◽  
Shuiqin Fang ◽  
Shaoye Wan ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Tandem Repeats ◽  
Expression System ◽  
Peptide Vaccine ◽  
Surface Protein ◽  
Infection Model ◽  
Protein Antigens ◽  
Epitope Peptide ◽  
Prokaryotic Expression System

Campylobacter jejuni (C. jejuni) is one of the major pathogens contributing to the enteritis in humans. Infection can lead to numerous complications, including but not limited to Guillain-Barre syndrome, reactive arthritis, and Reiter’s syndrome. Over the past two decades, joint efforts have been made toward developing a proper strategy of limiting the transmission of C. jejuni to humans. Nevertheless, except for biosecurity measures, no available vaccine has been developed so far. Judging from the research findings, Omp18, AhpC outer membrane protein, and FlgH flagellin subunits of C. jejuni could be adopted as surface protein antigens of C. jejuni for screening dominant epitope thanks to their strong antigenicity, expression of varying strains, and conservative sequence. In this study, bioinformatics technology was adopted to analyze the T-B antigenic epitopes of Omp18, AhpC, and FlgH in C. jejuni strain NCTC11168. Both ELISA and Western Blot methods were adopted to screen the dominant T-B combined epitope. GGS (GGCGGTAGC) sequence was adopted to connect the dominant T-B combined epitope peptides and to construct the prokaryotic expression system of tandem repeats of antigenic epitope peptides. The mouse infection model was adopted to assess the immunoprotective effect imposed by the trivalent T-B combined with antigen epitope peptide based on Omp18/AhpC/FlgH. In this study, a tandem epitope AhpC-2/Omp18-1/FlgH-1 was developed, which was composed of three epitopes and could effectively enhance the stability and antigenicity of the epitope while preserving its structure. The immunization of BALB/c mice with a tandem epitope could induce protective immunity accompanied by the generation of IgG2a antibody response through the in vitro synthesis of IFN-γ cytokines. Judging from the results of immune protection experiments, the colonization of C. jejuni declined to a significant extent, and it was expected that AhpC-2/Omp18-1/FlgH-1 could be adopted as a candidate antigen for genetic engineering vaccine of C. jejuni MAP.

scholarly journals The Novel Transcription Factor SgrR Coordinates the Response to Glucose-Phosphate Stress

2007 ◽  
Vol 189 (6) ◽  
pp. 2238-2248 ◽  
Author(s):  
Carin K. Vanderpool ◽  
Susan Gottesman
Keyword(s):  
Binding Site ◽  
Binding Domain ◽  
Alternative Mechanism ◽  
Gene Encoding ◽  
Bacterial Transcription ◽  
Glucose Phosphate ◽  
Plasmid Library ◽  
Promoter Dna

ABSTRACT SgrR is the first characterized member of a family of bacterial transcription factors containing an N-terminal DNA binding domain and a C-terminal solute binding domain. Previously, we reported genetic evidence that SgrR activates the divergently transcribed gene sgrS, which encodes a small RNA required for recovery from glucose-phosphate stress. In this study, we examined the regulation of sgrR expression and found that SgrR negatively autoregulates its own transcription in the presence and absence of stress. An SgrR binding site in the sgrR-sgrS intergenic region is required in vivo for both SgrR-dependent activation of sgrS and autorepression of sgrR. Purified SgrR binds specifically to sgrS promoter DNA in vitro; a mutation in the site required for in vivo activation and autorepression abrogates in vitro SgrR binding. A plasmid library screen identified clones that alter expression of a P sgrS -lacZ fusion; some act by titrating endogenous SgrR. The yfdZ gene, encoding a putative aminotransferase, was identified in this screen; the yfdZ promoter contains an SgrR binding site, and transcriptional fusions indicate that yfdZ is activated by SgrR. Clones containing mlc, which encodes a glucose-specific repressor protein, also downregulate P sgrS -lacZ. The mlc clones do not appear to titrate the SgrR protein, indicating that Mlc affects sgrS expression by an alternative mechanism.

scholarly journals Rapid production of SARS-CoV-2 receptor binding domain (RBD) and spike specific monoclonal antibody CR3022 in Nicotiana benthamiana

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kaewta Rattanapisit ◽  
Balamurugan Shanmugaraj ◽  
Suwimon Manopwisedjaroen ◽  
Priyo Budi Purwono ◽  
Konlavat Siriwattananon ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Receptor Binding ◽  
Nicotiana Benthamiana ◽  
Specific Binding ◽  
Expression System ◽  
Disease Diagnosis ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Global Public Health

Abstract Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the ongoing global outbreak of coronavirus disease (COVID-19) which is a significant threat to global public health. The rapid spread of COVID-19 necessitates the development of cost-effective technology platforms for the production of vaccines, drugs, and protein reagents for appropriate disease diagnosis and treatment. In this study, we explored the possibility of producing the receptor binding domain (RBD) of SARS-CoV-2 and an anti-SARS-CoV monoclonal antibody (mAb) CR3022 in Nicotiana benthamiana. Both RBD and mAb CR3022 were transiently produced with the highest expression level of 8 μg/g and 130 μg/g leaf fresh weight respectively at 3 days post-infiltration. The plant-produced RBD exhibited specific binding to the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2). Furthermore, the plant-produced mAb CR3022 binds to SARS-CoV-2, but fails to neutralize the virus in vitro. This is the first report showing the production of anti-SARS-CoV-2 RBD and mAb CR3022 in plants. Overall these findings provide a proof-of-concept for using plants as an expression system for the production of SARS-CoV-2 antigens and antibodies or similar other diagnostic reagents against SARS-CoV-2 rapidly, especially during epidemic or pandemic situation.

Synthesis of an enzymatically active FLP recombinase in vitro: search for a DNA-binding domain

1989 ◽  
Vol 9 (5) ◽  
pp. 1987-1995
Author(s):  
A A Amin ◽  
P D Sadowski
Keyword(s):  
Amino Acid ◽  
Dna Binding ◽  
In Vitro Transcription ◽  
Binding Activity ◽  
Binding Domain ◽  
Translation System ◽  
Dna Binding Domain ◽  
Amino Terminal ◽  
Dna Binding Activity

We have used an in vitro transcription and translation system to synthesize an enzymatically active FLP protein. The FLP mRNA synthesized in vitro by SP6 polymerase is translated efficiently in a rabbit reticulocyte lysate to produce enzymatically active FLP. Using this system, we assessed the effect of deletions and tetrapeptide insertions on the ability of the respective variant proteins synthesized in vitro to bind to the FLP recognition target site and to carry out excisive recombination. Deletions of as few as six amino acids from either the carboxy- or amino-terminal region of FLP resulted in loss of binding activity. Likewise, insertions at amino acid positions 79, 203, and 286 abolished DNA-binding activity. On the other hand, a protein with an insertion at amino acid 364 retained significant DNA-binding activity but had no detectable recombination activity. Also, an insertion at amino acid 115 had no measurable effect on DNA binding, but recombination was reduced by 95%. In addition, an insertion at amino acid 411 had no effect on DNA binding and recombination. On the basis of these results, we conclude that this approach fails to define a discrete DNA-binding domain. The possible reasons for this result are discussed.

Production of recombinant IGF1 and its action on neuroblastoma cells in vitro

2018 ◽  
Vol 18 (4) ◽  
pp. 34-41
Author(s):  
Sergey A. Ishuk ◽  
Elena G. Bogomolova ◽  
Olga A. Dobrovolskaya ◽  
Alyona O. Akhmetshina ◽  
Daria S. Krasnoshchek ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Recombinant Protein ◽  
Cation Exchange ◽  
Expression System ◽  
Neuroblastoma Cells ◽  
Exchange Chromatography ◽  
Cation Exchange Chromatography ◽  
Recombinant Insulin ◽  
Prokaryotic Expression System

This study aimed to develop a method for producing human recombinant insulin-like growth factor (IGF-1) based on a prokaryotic expression system and to characterize the highly purified protein. To achieve the study’s goal, the following methods were conducted: we performed automated chemical synthesis of DNA, constructed the expression plasmid, obtained Escherichia coli cell-producers of human recombinant IGF-1, cultivated the obtained producer cells with the induction of recombinant protein synthesis by isopropyl-β-D-1-thiogalactopyranoside and lactose, and purified human recombinant IGF-1 with affinity and cation exchange chromatography. The recombinant protein IGF-1 forms inclusion bodies during synthesis in Escherichia coli BL21 cells that contain plasmid pET28-IGF-1. Purified recombinant protein was obtained with a purity of 98% using affinity and cation exchange chromatography methods. The protein yield was 6 mg of human recombinant IGF-1 from 1 g of raw biomass. The resulting protein has the ability to protect Neuro 2a neuroblastoma cells from death caused by the deprivation of serum in the culture medium and can stimulate the differentiation of cells into neurons. Thus, a highly purified human recombinant IGF-1 was obtained. This protein has biological activity and is suitable for preclinical studies.

scholarly journals Competition between the Yops of Yersinia enterocolitica for Delivery into Eukaryotic Cells: Role of the SycE Chaperone Binding Domain of YopE

2000 ◽  
Vol 182 (17) ◽  
pp. 4811-4821 ◽  
Author(s):  
Aoife P. Boyd ◽  
Isabelle Lambermont ◽  
Guy R. Cornelis
Keyword(s):  
Binding Site ◽  
In Vitro Release ◽  
Inhibitory Effect ◽  
Binding Domain ◽  
Eukaryotic Cells ◽  
Target Cells ◽  
Wild Type ◽  
Animal Cells

ABSTRACT A type III secretion-translocation system allowsYersinia adhering at the surface of animal cells to deliver a cocktail of effector Yops (YopH, -O, -P, -E, -M, and -T) into the cytosol of these cells. Residues or codons 1 to 77 contain all the information required for the complete delivery of YopE into the target cell (release from the bacterium and translocation across the eukaryotic cell membrane). Residues or codons 1 to 15 are sufficient for release from the wild-type bacterium under Ca2+-chelating conditions but not for delivery into target cells. Residues 15 to 50 comprise the binding domain for SycE, a chaperone specific for YopE that is necessary for release and translocation of full-length YopE. To understand the role of this chaperone, we studied the delivery of YopE-Cya reporter proteins and YopE deletants by polymutant Yersinia devoid of most of the Yop effectors (ΔHOPEM and ΔTHE strains). We first tested YopE-Cya hybrid proteins and YopE proteins deleted of the SycE-binding site. In contrast to wild-type strains, these mutants delivered YopE15-Cya as efficiently as YopE130-Cya. They were also able to deliver YopEΔ17–77. SycE was dispensable for these deliveries. These results show that residues or codons 1 to 15 are sufficient for delivery into eukaryotic cells and that there is no specific translocation signal in Yops. However, the fact that the SycE-binding site and SycE were necessary for delivery of YopE by wild-type Yersinia suggests that they could introduce hierarchy among the effectors to be delivered. We then tested a YopE-Cya hybrid and YopE proteins deleted of amino acids 2 to 15 but containing the SycE-binding domain. These constructs were neither released in vitro upon Ca2+ chelation nor delivered into cells by wild-type or polymutant bacteria, casting doubts on the hypothesis that SycE could be a secretion pilot. Finally, it appeared that residues 50 to 77 are inhibitory to YopE release and that binding of SycE overcomes this inhibitory effect. Removal of this domain allowed in vitro release and delivery in cells in the absence as well as in the presence of SycE.

The single CH domain of calponin is neither sufficient nor necessary for F-actin binding

1998 ◽  
Vol 111 (13) ◽  
pp. 1813-1821 ◽  
Author(s):  
M. Gimona ◽  
R. Mital
Keyword(s):  
Binding Site ◽  
Tandem Repeats ◽  
Actin Binding ◽  
Carboxyl Terminus ◽  
Amino Terminus ◽  
Binding Motif ◽  
Amino Terminal ◽  
Nonmuscle Cells ◽  
Carboxy Terminal

Calponins have been implicated in the regulation of actomyosin interactions in smooth muscle cells, cytoskeletal organisation in nonmuscle cells, and the control of neurite outgrowth. Domains homologous to the amino-terminal region of calponin have been identified in a variety of actin cross-linking proteins and signal transduction molecules, and by inference these ‘calponin homology (CH) domains’ have been assumed to participate in actin binding. We here report on the actin binding activities of the subdomains of the calponin molecule. All three mammalian isoforms of calponin (basic h1, neutral h2 and acidic) possess a single CH domain at their amino terminus as well as three tandem repeats proximal to the carboxyl terminus. Calponin h2 differs, however, from h1 in lacking a consensus actin-binding motif in the region 142–163, between the CH domain and the tandem repeats, which in h1 calponin can be chemically cross-linked to actin. Despite the absence of this consensus actin-binding motif, recombinant full-length h2 calponin co-sediments in vitro with F-actin, suggesting the presence of another binding site in the molecule. It could be shown that this binding site resides in the C-terminal tandem repeats and not in the CH domain. Thus, constructs of h2 calponin bearing partial or complete deletions of the triple repeated sequences failed to co-localise with actin stress fibres despite the presence of a CH domain. Deletion of the acidic carboxyl terminus, beyond the repeats, increased actin binding, suggesting that the carboxy-terminal tail may modulate actin association. Results obtained from transient transfections of amino- and carboxy-terminal truncations in h1 calponin were consistent with the established location of the actin binding motif outside and carboxy-terminal to the CH domain, and confirm that the presence of a single CH domain alone is neither sufficient nor necessary to mediate actin binding. Instead, the carboxy-terminal tandem repeats of h1 and h2 calponin are shown to harbour a second, independent actin binding motif.

scholarly journals Characterization of pp60src phosphorylation in vitro in Rous sarcoma virus-transformed cell membranes.

1985 ◽  
Vol 5 (5) ◽  
pp. 916-922 ◽  
Author(s):  
M D Resh ◽  
R L Erikson
Keyword(s):  
Plasma Membrane ◽  
Rous Sarcoma Virus ◽  
Membrane Vesicles ◽  
Terminal Region ◽  
Transformed Cell ◽  
Amino Terminal ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
Carboxy Terminal

Phosphorylation of the src gene product pp60v-src was studied in plasma membrane fractions prepared from Rous sarcoma virus-transformed vole cells. Upon addition of [gamma-32P]ATP to isolated membrane vesicles, phosphate was incorporated into a 60,000-dalton polypeptide identified as pp60v-src. In the presence of vanadate, pp60v-src phosphorylation was stimulated ca. 30-fold. At low concentrations of ATP (1 microM), this reaction occurred almost exclusively on the carboxy-terminal 26,000-dalton region of pp60v-src. However, at higher ATP concentrations (100 microM), additional sites of phosphorylation were evident in the amino-terminal 34,000-dalton region. Kinetic analyses, performed under conditions in which ATP hydrolysis was minimal, revealed that the phosphorylation reaction at the carboxy terminus exhibited a higher Vmax and a lower Km for ATP than those occurring at the amino terminus. In addition, the amino-terminal region of pp60v-src was more rapidly dephosphorylated than the carboxy-terminal region. These results indicate that interaction of pp60v-src with the plasma membrane may limit the extent of amino-terminal phosphorylation by lowering the rate of the reaction and the affinity for the substrate while increasing its susceptibility to phosphoprotein phosphatases. We suggest that the use of transformed-cell membrane preparations provides a model system for studying the possible regulatory roles of phosphorylation and dephosphorylation on pp60v-src function.

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