scholarly journals Cryo-Electron Microscopy and Biochemical Analysis Offer Insights Into the Effects of Acidic pH, Such as Occur During Acidosis, on the Complement Binding Properties of C-Reactive Protein

2021 ◽  
Vol 12 ◽  
Author(s):  
Dylan P. Noone ◽  
Tijn T. van der Velden ◽  
Thomas H. Sharp
Keyword(s):  
Electron Microscopy ◽  
Biochemical Analysis ◽  
Biochemical Properties ◽  
Structural Basis ◽  
Structural Rearrangements ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Cryo Electron Microscopy ◽  
Ionic Nature ◽  
The Complement System

The pentraxin family of proteins includes C-reactive protein (CRP), a canonical marker for the acute phase inflammatory response. As compared to normal physiological conditions in human serum, under conditions associated with damage and inflammation, such as acidosis and the oxidative burst, CRP exhibits modulated biochemical properties that may have a structural basis. Here, we explore how pH and ligand binding affect the structure and biochemical properties of CRP. Cryo-electron microscopy was used to solve structures of CRP at pH 7.5 or pH 5 and in the presence or absence of the ligand phosphocholine (PCh), which yielded 7 new high-resolution structures of CRP, including pentameric and decameric complexes. Structures previously derived from crystallography were imperfect pentagons, as shown by the variable angles between each subunit, whereas pentameric CRP derived from cryoEM was found to have C5 symmetry, with subunits forming a regular pentagon with equal angles. This discrepancy indicates flexibility at the interfaces of monomers that may relate to activation of the complement system by the C1 complex. CRP also appears to readily decamerise in solution into dimers of pentamers, which obscures the postulated binding sites for C1. Subtle structural rearrangements were observed between the conditions tested, including a putative change in histidine protonation that may prime the disulphide bridges for reduction and enhanced ability to activate the immune system. Enzyme-linked immunosorbent assays showed that CRP had markedly increased association to the C1 complex and immunoglobulins under conditions associated with acidosis, whilst a reduction in the Ca2+ concentration lowered this pH-sensitivity for C1q, but not immunoglobulins, suggesting different modes of binding. These data suggest a model whereby a change in the ionic nature of CRP and immunological proteins can make it more adhesive to potential ligands without large structural rearrangements.

scholarly journals Interactions of C-reactive protein with the complement system. III. Complement-dependent passive hemolysis initiated by CRP.

1975 ◽  
Vol 142 (5) ◽  
pp. 1065-1077 ◽  
Author(s):  
A.P. Osmand ◽  
R.F. Mortensen ◽  
Joan Siegel ◽  
H. Gewurz
Keyword(s):  
Guinea Pig ◽  
Human Serum ◽  
Complete System ◽  
Gel Filtration ◽  
C Reactive Protein ◽  
Inflammatory Reactions ◽  
Reactive Protein ◽  
Rabbit Igg ◽  
The Complement System ◽  
Pig Serum

Interactions of CRP with various substrates in the presence of human serum have been shown to result in efficient activation of C components C1-C5. We now report the ability of CRP to initiate C-dependent hemolysis. For this purpose CRP was isolated by affinity chromatography using pneumococcal CPS and gel filtration; its purity was established by several criteria. Erythrocytes were coated with CPS (E-CPS) and passively sensitized with CRP. C-dependent lysis of these cells was observed upon the addition of suitably absorbed human serum, and the efficiency of hemolysis compared favorably with that initiated by rabbit IgG anti-CPS antibody. CRP also sensitized E-CPS for lysis by guinea pig C; partial lysis was seen when C4-deficient guinea pig serum was used, suggesting that CRP also shares with antibody the ability of CRP to fully activate the C system and provide further evidence for a role for CRP similar to that of antibody in the initiation and modulation of inflammatory reactions via the complete system.

scholarly journals COMPARATIVE EFFECTIVENESS OF VARIOUS SCHEMES OF IMMUNOREHABILITATION IN INFERTILITY OF TUBOPERITONEAL GENESIS

2021 ◽  
Vol 23 (4) ◽  
pp. 927-932
Author(s):  
O. B.J. Po ◽  
A. A. Konoplya ◽  
I. N. Medvedeva
Keyword(s):  
Polymorphonuclear Leukocytes ◽  
Local Level ◽  
Control Group ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Vitamin Therapy ◽  
Dependent Activity ◽  
Peroxidation Processes ◽  
Nitric Oxide Metabolites ◽  
The Complement System

The study aimed to compare the effectiveness of various pharmacotherapy regimens for infertility of tubo-peritoneal genesis. Under constant supervision were 96 patients referred to the hospital for diagnostic laparoscopy for infertility of tubo-peritoneal genesis, divided equally into 4 groups depending on the pharmacological treatment methods: the 1st group received basic pharmacotherapy (BPT) after endoscopic surgery (antibacterial, antifungal, vitamin therapy). Patients of groups 2-4, in addition to BPT, received Hepon, Cycloferon or Lavomax, respectively. The control group consisted of 38 gynecologically healthy women. Laboratory examination was performed within 24 hours after the operation and on the 30th day after BPT. Vaginocervical lavage and plasma were assayed for the activity of lipid peroxidation processes, the state of the antioxidant system, the level of stable nitric oxide metabolites, neopterin, C-reactive protein, cytokines (TNFα, IL-1β, IL-8, IFNγ, IL-18, G-CSF, IL-4, IL-10), immunoglobulins (IgM, IgG, IgA, sIgA), components of the complement system (C3, C4, C5, C5А), phagocytic and oxygen-dependent activity of polymorphonuclear leukocytes. It was established that the use of immunomodulatory and antiviral activity medication with BPT according to the degree of increasing efficiency in the correction of immunometabolic laboratory parameters at the systemic and local level in infertility of tuboperitoneal genesis is as the following sequence: basic pharmacotherapy < basic pharmacotherapy + Hepon < basic pharmacotherapy + Cycloferon < basic pharmacotherapy + Lavomax. 

scholarly journals Cryo-EM structure and polymorphism of Aβ amyloid fibrils purified from Alzheimer’s brain tissue

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Marius Kollmer ◽  
William Close ◽  
Leonie Funk ◽  
Jay Rasmussen ◽  
Aref Bsoul ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Brain Tissue ◽  
Amyloid Fibrils ◽  
Structural Basis ◽  
Amyloid Angiopathy ◽  
Cryo Electron Microscopy ◽  
Aβ Amyloid ◽  
Cerebral Amyloid ◽  
Aβ Fibrils

Abstract The formation of Aβ amyloid fibrils is a neuropathological hallmark of Alzheimer’s disease and cerebral amyloid angiopathy. However, the structure of Aβ amyloid fibrils from brain tissue is poorly understood. Here we report the purification of Aβ amyloid fibrils from meningeal Alzheimer’s brain tissue and their structural analysis with cryo-electron microscopy. We show that these fibrils are polymorphic but consist of similarly structured protofilaments. Brain derived Aβ amyloid fibrils are right-hand twisted and their peptide fold differs sharply from previously analyzed Aβ fibrils that were formed in vitro. These data underscore the importance to use patient-derived amyloid fibrils when investigating the structural basis of the disease.

How Good Can Single-Particle Cryo-EM Become? What Remains Before It Approaches Its Physical Limits?

2019 ◽  
Vol 48 (1) ◽  
pp. 45-61 ◽  
Author(s):  
Robert M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Single Particle ◽  
Energy Use ◽  
Optimal Choice ◽  
Structural Basis ◽  
Detective Quantum Efficiency ◽  
Quantum Metrology ◽  
Cryo Electron Microscopy ◽  
Induced Motion

Impressive though the achievements of single-particle cryo–electron microscopy are today, a substantial gap still remains between what is currently accomplished and what is theoretically possible. As is reviewed here, twofold or more improvements are possible as regards ( a) the detective quantum efficiency of cameras at high resolution, ( b) converting phase modulations to intensity modulations in the image, and ( c) recovering the full amount of high-resolution signal in the presence of beam-induced motion of the specimen. In addition, potential for improvement is reviewed for other topics such as optimal choice of electron energy, use of aberration correctors, and quantum metrology. With the help of such improvements, it does not seem to be too much to imagine that determining the structural basis for every aspect of catalytic control, signaling, and regulation, in any type of cell of interest, could easily be accelerated fivefold or more.

scholarly journals Interactions of C-reactive protein with the complement system. II. C-reactive protein-mediated consumption of complement by poly-L-lysine polymers and other polycations.

1975 ◽  
Vol 142 (3) ◽  
pp. 709-721 ◽  
Author(s):  
J Siegel ◽  
A P Osmand ◽  
M F Wilson ◽  
H Gewurz
Keyword(s):  
Inflammatory Response ◽  
Potential Role ◽  
Egg White ◽  
Phosphate Esters ◽  
C Reactive Protein ◽  
Cationic Proteins ◽  
Reactive Protein ◽  
Naturally Occurring ◽  
The Complement System

Cationic homopolymers of poly-L-lysine were found to activate complement (C) via C-reactive protein (CRP) and deplete C3 and C5 as well as early-acting C components. Maximum C consumption was obtained with polymers of 2,000-8,000 daltons; polymers of 1,700, 11,000, and 23,000 daltons were intermediate in reactivity, while L-lysine, lysyl-L-lysine, tetra-L-lysine, and polymers of 70,000-400,000 daltons lacked significant C-consuming activity. Naturally occurring polycations which consumed C in the presence of CRP included myelin basic proteins, cationic proteins of rabbit leukocytes, and both lysine- and arginine-rich histones; poly-L-arginine polymers of 17,000 but not 65,000 daltons also were C-consuming. Polycations without such reactivity included poly-L-orithine (5,000 and 165,000 daltons), egg white and human lysozymes, and Polybrene. The polycations which failed to induce C consumption via CRP, inhibited its consumption by both active polycations and by C-polysaccharide (CPS). The relative inhibitory capacity of phosphorylcholine and polycations in CPS- and polycations-CRP systems was consistent with the concept that phosphate esters and polycations react at the same or an overlapping combining site. The ability of certain polycations to activate C via CRP increases the potential for initiation of host reactions via C. The capacity of other polycations to inhibit C activation via CRP introduces a potential for physiologic or pharmacologic manipulation. These considerations would seem to expand the potential role of CRP in the initiation and modulation of the inflammatory response.

scholarly journals Structural basis of actin filament capping at the barbed-end: a cryo-electron microscopy study

2006 ◽  
Vol 25 (23) ◽  
pp. 5626-5633 ◽  
Author(s):  
Akihiro Narita ◽  
Shuichi Takeda ◽  
Atsuko Yamashita ◽  
Yuichiro Maéda
Keyword(s):  
Electron Microscopy ◽  
Actin Filament ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Structural Basis ◽  
Cryo Electron Microscopy

scholarly journals Elucidation of AMPA receptor–stargazin complexes by cryo–electron microscopy

Science ◽  
2016 ◽  
Vol 353 (6294) ◽  
pp. 83-86 ◽  
Author(s):  
Edward C. Twomey ◽  
Maria V. Yelshanskaya ◽  
Robert A. Grassucci ◽  
Joachim Frank ◽  
Alexander I. Sobolevsky
Keyword(s):  
Electron Microscopy ◽  
Cognitive Processes ◽  
Electrostatic Interactions ◽  
Structural Basis ◽  
Cryo Electron Microscopy ◽  
Activated State ◽  
Ampar Trafficking ◽  
Excitatory Neurotransmission ◽  
Binding Interfaces ◽  
The Brain

AMPA-subtype ionotropic glutamate receptors (AMPARs) mediate fast excitatory neurotransmission and contribute to high cognitive processes such as learning and memory. In the brain, AMPAR trafficking, gating, and pharmacology is tightly controlled by transmembrane AMPAR regulatory proteins (TARPs). Here, we used cryo–electron microscopy to elucidate the structural basis of AMPAR regulation by one of these auxiliary proteins, TARP γ2, or stargazin (STZ). Our structures illuminate the variable interaction stoichiometry of the AMPAR-TARP complex, with one or two TARP molecules binding one tetrameric AMPAR. Analysis of the AMPAR-STZ binding interfaces suggests that electrostatic interactions between the extracellular domains of AMPAR and STZ play an important role in modulating AMPAR function through contact surfaces that are conserved across AMPARs and TARPs. We propose a model explaining how TARPs stabilize the activated state of AMPARs and how the interactions between AMPARs and their auxiliary proteins control fast excitatory synaptic transmission.

scholarly journals Cryo-EM Reveals the Structural Basis of Microtubule Depolymerization by Kinesin-13s

2017 ◽  
Author(s):  
Matthieu P. M. H. Benoit ◽  
Ana B. Asenjo ◽  
Hernando Sosa
Keyword(s):  
Electron Microscopy ◽  
Conformational Changes ◽  
Distinct Group ◽  
Atomic Resolution ◽  
Structural Basis ◽  
Structural Elements ◽  
Microtubule Depolymerization ◽  
Cryo Electron Microscopy ◽  
Kinesin Superfamily ◽  
Motile Activity

SummaryKinesin-13s constitute a distinct group within the kinesin superfamily of motor proteins that promotes microtubule depolymerization and lacks motile activity. The molecular mechanism by which the kinesins depolymerize microtubules and are adapted to perform a seemingly very different activity from other kinesins is still unclear. To address this issue we obtained near atomic resolution cryo-electron microscopy (cryo-EM) structures of Drosophila melanogaster kinesin-13 KLP10A constructs bound to curved or straight tubulin in different nucleotide states. The structures show how nucleotide induced conformational changes near the catalytic site are coupled with kinesin-13-specific structural elements to induce tubulin curvature leading to microtubule depolymerization. The data highlight a modular structure that allows similar kinesin core motor-domains to be used for different functions, such as motility or microtubule depolymerization.

scholarly journals Features of a new Coronavirus infection in children of different ages

2021 ◽  
Vol 20 (2) ◽  
pp. 5-9
Author(s):  
M. A. Shakmaeva ◽  
T. M. Chernova ◽  
V. N. Timchenko ◽  
T. A. Nachinkina ◽  
K. V. Tetyushin ◽  
...  
Keyword(s):  
Biochemical Analysis ◽  
Pathological Process ◽  
Upper Respiratory Tract ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Source Of Infection ◽  
Different Ages ◽  
Coronavirus Infection ◽  
Upper Respiratory ◽  
One Year

The new coronavirus infection (COVID-1 9) is a socially significant problem around the world. According to available statistics, complications are less common among children, asymptomatic or mild forms of the disease prevail more often.This article presents the features of the viral landscape of the upper respiratory tract in children with ARVI in a pandemic, the clinical and laboratory features of the course of COVID-1 9 in children of different ages.It was found that SARS-CoV-2 is detected only in a third (32.9%) of hospitalized patients with respiratory symptoms, in 4.3% of cases — in combination with seasonal CoV-OC43 / CoV-229E, in 1 1.6% — with other respiratory viruses. The most frequent source of infection with the SARS-Cov-2 were family members. Children with a moderate form of the disease predominated among the patients. The leading symptoms of COVID-19 were fever, catarrhal symptoms, as well as gastrointestinal manifestations and anosmia. A feature of the new coronavirus infection in newborns and children of the first month of life was the absence of fever and intoxication, the lack of expression of catarrhal manifestations when the colon is involved in the pathological process (colitis, rarely — hemocolitis). In the compete blood test in children under the age of one year, monocytosis prevailed, in children over 7 years old — leukopenia and accelerated ESR. Among the changes in the biochemical analysis of blood, the most common was an increased C-reactive protein.

scholarly journals Molecular basis for the ATPase-powered substrate translocation by the Lon AAA+ protease

2020 ◽  
Author(s):  
Kaiming Zhang ◽  
Shanshan Li ◽  
Kan-Yen Hsieh ◽  
Shih-Chieh Su ◽  
Grigore D. Pintilie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Conformational Changes ◽  
Molecular Basis ◽  
Structural Basis ◽  
Cryo Electron Microscopy ◽  
Adenosine Triphosphatases ◽  
Translocation Mechanism ◽  
Atp Binding And Hydrolysis ◽  
Proteolytic Chamber ◽  
Specific Nucleotide

AbstractThe Lon AAA+ (adenosine triphosphatases associated with diverse cellular activities) protease (LonA) converts ATP-fuelled conformational changes into sufficient mechanical force to drive translocation of the substrate into a hexameric proteolytic chamber. To understand the structural basis for the substrate translocation process, we have determined the cryo-electron microscopy (cryo-EM) structure of Meiothermus taiwanensis LonA (MtaLonA) at 3.6 Å resolution in a substrate-engaged state. Substrate interactions are mediated by the dual pore-loops of the ATPase domains, organized in spiral staircase arrangement from four consecutive protomers in different ATP-binding and hydrolysis states; a closed AAA+ ring is nevertheless maintained by two disengaged ADP-bound protomers transiting between the lowest and highest position. The structure reveals a processive rotary translocation mechanism mediated by LonA-specific nucleotide-dependent allosteric coordination among the ATPase domains, which is induced by substrate binding.

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