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Martin L, Martin JA, Audran M, Marchand A. An optimized SDS-PAGE protocol with a new blotting system for the initial testing procedure of ESAs in doping control. Drug Test Anal 2020; 14:181-187. [PMID: 33269539 DOI: 10.1002/dta.2601] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 03/21/2019] [Accepted: 03/30/2019] [Indexed: 11/11/2022]
Abstract
Recombinant erythropoietins (rEPOs) are still among the substances endurance athletes use for doping. Detection methods are based on an electrophoretic separation of the proteins followed by a western blot and immunodetection with specific anti-EPO antibodies. In addition to IEF-PAGE, the SDS-PAGE method has been used to differentiate endogenous EPO from rEPOs by their molecular weight (MW). However, to adapt to new generations of rEPOs exhibiting higher MW, which were not well detected after SDS-PAGE, sodium lauroyl sarcosinate (SAR) is now used instead of sodium dodecyl sulfate (SDS) for the initial EPO testing procedure on doping control samples. The SAR-PAGE method is nevertheless expensive as it requires frequent buffer preparations using highly purified sarkosyl powder. In addition, this reagent needs to be handled with care due to acute toxicity by inhalation. The aim of this work was to improve the SDS-PAGE method by increasing its sensitivity and transfer of high-MW rEPOs. First, using a biotinylated primary anti-EPO antibody and avoiding the use of a secondary antibody increased the general sensitivity of both SDS-PAGE and SAR-PAGE to all rEPOs about four-fold. Then, by changing the buffer system during the protein transfer, with a CAPS buffer and a discontinuous buffer transfer system, high-MW rEPOs, EPO-Fc and CERA were transferred with higher efficiency and detected with high sensitivity. This optimized SDS-PAGE protocol could be adopted by anti-doping laboratories as an alternative to SAR-PAGE.
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Affiliation(s)
- Laurent Martin
- Analysis Department, Agence Française de Lutte contre le Dopage (AFLD), Châtenay-Malabry, France
| | - Jean-Antoine Martin
- Analysis Department, Agence Française de Lutte contre le Dopage (AFLD), Châtenay-Malabry, France
| | - Michel Audran
- Analysis Department, Agence Française de Lutte contre le Dopage (AFLD), Châtenay-Malabry, France
| | - Alexandre Marchand
- Analysis Department, Agence Française de Lutte contre le Dopage (AFLD), Châtenay-Malabry, France
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Ukwaththage TO, Goodwin OY, Songok AC, Tafaro AM, Shen L, Macnaughtan MA. Purification of Tag-Free Chlamydia trachomatis Scc4 for Structural Studies Using Sarkosyl-Assisted on-Column Complex Dissociation. Biochemistry 2019; 58:4284-4292. [PMID: 31545893 DOI: 10.1021/acs.biochem.9b00665] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Chlamydia trachomatis is an obligate intracellular bacterial pathogen that causes the most common sexually transmitted bacterial disease in the world. The bacterium has a unique biphasic developmental cycle with a type III secretion system (T3SS) to invade host cells. Scc4 is a class I T3SS chaperone forming a heterodimer complex with Scc1 to chaperone the essential virulence effector, CopN. Scc4 also functions as an RNA polymerase binding protein to regulate σ66-dependent transcription. Aggregation and low solubility of 6X-histidine-tagged Scc4 and the insolubility of 6X-histidine and FLAG-tagged Scc1 expressed in Escherichia coli have hindered the high-resolution nuclear magnetic resonance (NMR) structure determination of these proteins and motivated the development of an on-column complex dissociation method to produce tag-free Scc4 and soluble FLAG-tagged Scc1. By utilizing a 6X-histidine-tag on one protein, the coexpressed Scc4-Scc1 complex was captured on nickel-charged immobilized metal affinity chromatography resin, and the nondenaturing detergent, sodium N-lauroylsarcosine (sarkosyl), was used to dissociate and elute the non-6X-histidine-tagged protein. Tag-free Scc4 was produced in a higher yield and had better NMR spectral characteristics compared to 6X-histidine-tagged Scc4, and soluble FLAG-tagged Scc1 was purified for the first time in a high yield. The backbone structure of Scc4 after exposure to sarkosyl was validated using NMR spectroscopy, demonstrating the usefulness of the method to produce proteins for structural and functional studies. The sarkosyl-assisted on-column complex dissociation method is generally applicable to protein complexes with high affinity and is particularly useful when affinity tags alter the protein's biophysical properties or when coexpression is necessary for solubility.
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Affiliation(s)
- Thilini O Ukwaththage
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Octavia Y Goodwin
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Abigael C Songok
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Alexa M Tafaro
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Li Shen
- Department of Microbiology, Immunology, and Parasitology , Louisiana State University Health Sciences Center , New Orleans , Louisiana 70112 , United States
| | - Megan A Macnaughtan
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
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Rahman S, Yamato I, Saijo S, Mizutani K, Takamuku Y, Ishizuka-Katsura Y, Ohsawa N, Terada T, Shirouzu M, Yokoyama S, Murata T. Binding interactions of the peripheral stalk subunit isoforms from human V-ATPase. Biosci Biotechnol Biochem 2016; 80:878-90. [PMID: 26865189 DOI: 10.1080/09168451.2015.1135043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The mammalian peripheral stalk subunits of the vacuolar-type H(+)-ATPases (V-ATPases) possess several isoforms (C1, C2, E1, E2, G1, G2, G3, a1, a2, a3, and a4), which may play significant role in regulating ATPase assembly and disassembly in different tissues. To better understand the structure and function of V-ATPase, we expressed and purified several isoforms of the human V-ATPase peripheral stalk: E1G1, E1G2, E1G3, E2G1, E2G2, E2G3, C1, C2, H, a1NT, and a2NT. Here, we investigated and characterized the isoforms of the peripheral stalk region of human V-ATPase with respect to their affinity and kinetics in different combination. We found that different isoforms interacted in a similar manner with the isoforms of other subunits. The differences in binding affinities among isoforms were minor from our in vitro studies. However, such minor differences from the binding interaction among isoforms might provide valuable information for the future structural-functional studies of this holoenzyme.
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Affiliation(s)
- Suhaila Rahman
- a Department of Biological Science and Technology , Tokyo University of Science , Tokyo , Japan
| | - Ichiro Yamato
- a Department of Biological Science and Technology , Tokyo University of Science , Tokyo , Japan
| | - Shinya Saijo
- a Department of Biological Science and Technology , Tokyo University of Science , Tokyo , Japan
| | - Kenji Mizutani
- a Department of Biological Science and Technology , Tokyo University of Science , Tokyo , Japan.,b Department of Chemistry , Graduate School of Science, Chiba University , Chiba , Japan
| | - Yuuki Takamuku
- b Department of Chemistry , Graduate School of Science, Chiba University , Chiba , Japan
| | | | - Noboru Ohsawa
- c RIKEN Systems and Structural Biology Center , Yokohama , Japan
| | - Takaho Terada
- c RIKEN Systems and Structural Biology Center , Yokohama , Japan
| | - Mikako Shirouzu
- c RIKEN Systems and Structural Biology Center , Yokohama , Japan
| | - Shigeyuki Yokoyama
- c RIKEN Systems and Structural Biology Center , Yokohama , Japan.,d Department of Biophysics and Biochemistry , Graduate School of Science, The University of Tokyo , Tokyo , Japan
| | - Takeshi Murata
- b Department of Chemistry , Graduate School of Science, Chiba University , Chiba , Japan.,c RIKEN Systems and Structural Biology Center , Yokohama , Japan.,e Molecular Chirality Research Center, Chiba University , Chiba , Japan.,f JST, PRESTO , Chiba , Japan
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Natale G, Pompili E, Biagioni F, Paparelli S, Lenzi P, Fornai F. Histochemical approaches to assess cell-to-cell transmission of misfolded proteins in neurodegenerative diseases. Eur J Histochem 2013; 57:e5. [PMID: 23549464 PMCID: PMC3683612 DOI: 10.4081/ejh.2013.e5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/07/2012] [Accepted: 09/07/2012] [Indexed: 12/13/2022] Open
Abstract
Formation, aggregation and transmission of abnormal proteins are common features in neurodegenerative disorders including Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, and Huntington's disease. The mechanisms underlying protein alterations in neurodegenerative diseases remain controversial. Novel findings highlighted altered protein clearing systems as common biochemical pathways which generate protein misfolding, which in turn causes protein aggregation and protein spreading. In fact, proteinaceous aggregates are prone to cell-to-cell propagation. This is reminiscent of what happens in prion disorders, where the prion protein misfolds thus forming aggregates which spread to neighbouring cells. For this reason, the term prionoids is currently used to emphasize how several misfolded proteins are transmitted in neurodegenerative diseases following this prion-like pattern. Histochemical techniques including the use of specific antibodies covering both light and electron microscopy offer a powerful tool to describe these phenomena and investigate specific molecular steps. These include: prion like protein alterations; glycation of prion-like altered proteins to form advanced glycation end-products (AGEs); mechanisms of extracellular secretion; interaction of AGEs with specific receptors placed on neighbouring cells (RAGEs). The present manuscript comments on these phenomena aimed to provide a consistent scenario of the available histochemical approaches to dissect each specific step.
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Affiliation(s)
- G Natale
- Department of Human Morphology and Applied Biology, University of Pisa, Pisa, Italy
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Rahman S, Yamato I, Saijo S, Mizutani K, Ishizuka-Katsura Y, Ohsawa N, Terada T, Shirouzu M, Yokoyama S, Iwata S, Murata T. Biochemical and biophysical properties of interactions between subunits of the peripheral stalk region of human V-ATPase. PLoS One 2013; 8:e55704. [PMID: 23409023 PMCID: PMC3569449 DOI: 10.1371/journal.pone.0055704] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 12/28/2012] [Indexed: 11/18/2022] Open
Abstract
Peripheral stalk subunits of eukaryotic or mammalian vacuolar ATPases (V-ATPases) play key roles in regulating its assembly and disassembly. In a previous study, we purified several subunits and their isoforms of the peripheral stalk region of Homo sapiens (human) V-ATPase; such as C1, E1G1, H, and the N-terminal cytoplasmic region of V(o), a1. Here, we investigated the in vitro binding interactions of the subunits at the stalk region and measured their specific affinities. Surface plasmon resonance experiments revealed that the subunit C1 binds the E1G1 heterodimer with both high and low affinities (2.8 nM and 1.9 µM, respectively). In addition, an E1G1-H complex can be formed with high affinity (48 nM), whereas affinities of other subunit pairs appeared to be low (∼0.21-3.0 µM). The putative ternary complex of C1-H-E1G1 was not much strong on co-incubation of these subunits, indicating that the two strong complexes of C1-E1G1 and H-E1G1 in cooperation with many other weak interactions may be sufficiently strong enough to withstand the torque of rotation during catalysis. We observed a partially stable quaternary complex (consisting of E1G1, C1, a1(NT), and H subunits) resulting from discrete peripheral subunit interactions stabilizing the complex through their intrinsic affinities. No binding was observed in the absence of E1G1 (using only H, C1, and a1(NT)); therefore, it is likely that, in vivo, the E1G1 heterodimer has a significant role in the initiation of subunit assembly. Multiple interactions of variable affinity in the stalk region may be important to the mechanism of reversible dissociation of the intact V-ATPase.
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Affiliation(s)
- Suhaila Rahman
- Department of Biological Science and Technology, Tokyo University of Science, Chiba, Japan.
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Parsons LS, Wilkens S. Probing subunit-subunit interactions in the yeast vacuolar ATPase by peptide arrays. PLoS One 2012; 7:e46960. [PMID: 23071676 PMCID: PMC3470569 DOI: 10.1371/journal.pone.0046960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 09/07/2012] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Vacuolar (H(+))-ATPase (V-ATPase; V(1)V(o)-ATPase) is a large multisubunit enzyme complex found in the endomembrane system of all eukaryotic cells where its proton pumping action serves to acidify subcellular organelles. In the plasma membrane of certain specialized tissues, V-ATPase functions to pump protons from the cytoplasm into the extracellular space. The activity of the V-ATPase is regulated by a reversible dissociation mechanism that involves breaking and re-forming of protein-protein interactions in the V(1)-ATPase - V(o)-proton channel interface. The mechanism responsible for regulated V-ATPase dissociation is poorly understood, largely due to a lack of detailed knowledge of the molecular interactions that are responsible for the structural and functional link between the soluble ATPase and membrane bound proton channel domains. METHODOLOGY/PRINCIPAL FINDINGS To gain insight into where some of the stator subunits of the V-ATPase associate with each other, we have developed peptide arrays from the primary sequences of V-ATPase subunits. By probing the peptide arrays with individually expressed V-ATPase subunits, we have identified several key interactions involving stator subunits E, G, C, H and the N-terminal domain of the membrane bound a subunit. CONCLUSIONS The subunit-peptide interactions identified from the peptide arrays complement low resolution structural models of the eukaryotic vacuolar ATPase obtained from transmission electron microscopy. The subunit-subunit interaction data are discussed in context of our current model of reversible enzyme dissociation.
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Affiliation(s)
- Lee S. Parsons
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, United States of America
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, United States of America
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Chang CC, Lin S, Lee CH, Chuang TL, Hsueh PR, Lai HC, Lin CW. Amplified surface plasmon resonance immunosensor for interferon-gamma based on a streptavidin-incorporated aptamer. Biosens Bioelectron 2012; 37:68-74. [PMID: 22626829 DOI: 10.1016/j.bios.2012.04.038] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 04/15/2012] [Accepted: 04/24/2012] [Indexed: 11/27/2022]
Abstract
Interferon-gamma (IFN-γ) is associated with susceptibility to tuberculosis, which is a major public health problem worldwide. Although significant progress has been made with regard to the design of enzyme immunoassays for IFN-γ, this assay is still labor-intensive and time-consuming. We therefore designed a DNA aptamer hairpin structure for the detection of IFN-γ with high sensitivity and selectivity. A streptavidin DNA aptamer was incorporated into the IFN-γ binding aptamer probe for the amplified detection of the target molecules. Initially, the probe remained in the inactive configuration. The addition of IFN-γ induced the rearrangement of the aptamer structure, allowing the self-assembly of the active streptavidin aptamer conformation for the streptavidin molecular recognition. Under optimized conditions, the detection limit was determined to be 33 pM, with a dynamic range from 0.3 to 333 nM, both of which were superior to those of corresponding optical sensors. Because combined aptamers are composed of nucleic acids, this optical aptasensor provided the advantages of high sensitivity, simplicity, reusability, and no further labeling or sample pre-treatment.
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Affiliation(s)
- Chia-Chen Chang
- Institute of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan
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