scholarly journals Rotavirus RNA polymerase requires the core shell protein to synthesize the double-stranded RNA genome.

1997 ◽  
Vol 71 (12) ◽  
pp. 9618-9626 ◽  
Author(s):  
J T Patton ◽  
M T Jones ◽  
A N Kalbach ◽  
Y W He ◽  
J Xiaobo
Keyword(s):  
Rna Polymerase ◽  
Core Shell ◽  
Double Stranded Rna ◽  
The Core ◽  
Shell Protein ◽  
Rna Genome

scholarly journals In Vitro Double-Stranded RNA Synthesis by Rotavirus Polymerase Mutants with Lesions at Core Shell Contact Sites

2019 ◽  
Vol 93 (20) ◽  
Author(s):  
Courtney L. Steger ◽  
Mackenzie L. Brown ◽  
Owen M. Sullivan ◽  
Crystal E. Boudreaux ◽  
Courtney A. Cohen ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Functional Significance ◽  
Rna Synthesis ◽  
Polymerase Activity ◽  
Core Shell ◽  
Double Stranded Rna ◽  
The Core ◽  
Contact Sites ◽  
Shell Protein

ABSTRACT The rotavirus polymerase VP1 mediates all stages of viral RNA synthesis within the confines of subviral particles and while associated with the core shell protein VP2. Transcription (positive-strand RNA [+RNA] synthesis) by VP1 occurs within double-layered particles (DLPs), while genome replication (double-stranded RNA [dsRNA] synthesis) by VP1 occurs within assembly intermediates. VP2 is critical for VP1 enzymatic activity; yet, the mechanism by which the core shell protein triggers polymerase function remains poorly understood. Structural analyses of transcriptionally competent DLPs show that VP1 is located beneath the VP2 core shell and sits slightly off-center from each of the icosahedral 5-fold axes. In this position, the polymerase is contacted by the core shell at 5 distinct surface-exposed sites, comprising VP1 residues 264 to 267, 547 to 550, 614 to 620, 968 to 980, and 1022 to 1025. Here, we sought to test the functional significance of these VP2 contact sites on VP1 with regard to polymerase activity. We engineered 19 recombinant VP1 (rVP1) proteins that contained single- or multipoint alanine mutations within each individual contact site and assayed them for the capacity to synthesize dsRNA in vitro in the presence of rVP2. Three rVP1 mutants (E265A/L267A, R614A, and D971A/S978A/I980A) exhibited diminished in vitro dsRNA synthesis. Despite their loss-of-function phenotypes, the mutants did not show major structural changes in silico, and they maintained their overall capacity to bind rVP2 in vitro via their nonmutated contact sites. These results move us toward a mechanistic understanding of rotavirus replication and identify precise VP2-binding sites on the polymerase surface that are critical for its enzymatic activation. IMPORTANCE Rotaviruses are important pathogens that cause severe gastroenteritis in the young of many animals. The viral polymerase VP1 mediates all stages of viral RNA synthesis, and it requires the core shell protein VP2 for its enzymatic activity. Yet, there are several gaps in knowledge about how VP2 engages and activates VP1. Here, we probed the functional significance of 5 distinct VP2 contact sites on VP1 that were revealed through previous structural studies. Specifically, we engineered alanine amino acid substitutions within each of the 5 VP1 regions and assayed the mutant polymerases for the capacity to synthesize RNA in the presence of VP2 in a test tube. Our results identified residues within 3 of the VP2 contact sites that are critical for robust polymerase activity. These results are important because they enhance the understanding of a key step of the rotavirus replication cycle.

scholarly journals The Hydrophilic Amino-Terminal Arm of Reovirus Core Shell Protein λ1 Is Dispensable for Particle Assembly

2002 ◽  
Vol 76 (23) ◽  
pp. 12211-12222 ◽  
Author(s):  
Jonghwa Kim ◽  
Xing Zhang ◽  
Victoria E. Centonze ◽  
Valorie D. Bowman ◽  
Simon Noble ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Capsid Proteins ◽  
Core Shell ◽  
Threefold Axis ◽  
Particle Assembly ◽  
Amino Terminal ◽  
The Core ◽  
Shell Protein ◽  
Core Proteins ◽  
Outer Capsid

ABSTRACT The reovirus core particle is a molecular machine that mediates synthesis, capping, and export of the viral plus strand RNA transcripts. Its assembly and structure-function relationships remain to be well understood. Following the lead of previous studies with other Reoviridae family members, most notably orbiviruses and rotaviruses, we used recombinant baculoviruses to coexpress reovirus core proteins λ1, λ2, and σ2 in insect cells. The resulting core-like particles (CLPs) were purified and characterized. They were found to be similar to cores with regard to their sizes, morphologies, and protein compositions. Like cores, they could also be coated in vitro with the two major outer-capsid proteins, μ1 and σ3, to produce virion-like particles. Coexpression of core shell protein λ1 and core nodule protein σ2 was sufficient to yield CLPs that could withstand purification, whereas expression of λ1 alone was not, indicating a required role for σ2 as a previous study also suggested. In addition, CLPs that lacked λ2 (formed from λ1 and σ2 only) could not be coated with μ1 and σ3, indicating a required role for λ2 in the assembly of these outer-capsid proteins into particles. To extend the use of this system for understanding the core and its assembly, we addressed the hypothesis that the hydrophilic amino-terminal region of λ1, which adopts an extended arm-like conformation around each threefold axis in the reovirus core crystal structure, plays an important role in assembling the core shell. Using a series of λ1 deletion mutants, we showed that the amino-terminal 230 residues of λ1, including its zinc finger, are dispensable for CLP assembly. Residues in the 231-to-259 region of λ1, however, were required. The core crystal structure suggests that residues in the 231-to-259 region are necessary because they affect the interaction of λ1 with the threefold and/or fivefold copies of σ2. An effective system for studies of reovirus core structure, assembly, and functions is hereby established.

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

scholarly journals Iron Based Core-Shell Structures as Versatile Materials: Magnetic Support and Solid Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Christian Zambrzycki ◽  
Runbang Shao ◽  
Archismita Misra ◽  
Carsten Streb ◽  
Ulrich Herr ◽  
...  
Keyword(s):  
Water Purification ◽  
Functional Materials ◽  
Core Material ◽  
Solid Catalyst ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Shell Nanostructures ◽  
Sio2 Shell ◽  
Iron Based

Core-shell materials are promising functional materials for fundamental research and industrial application, as their properties can be adapted for specific applications. In particular, particles featuring iron or iron oxide as core material are relevant since they combine magnetic and catalytic properties. The addition of an SiO2 shell around the core particles introduces additional design aspects, such as a pore structure and surface functionalization. Herein, we describe the synthesis and application of iron-based core-shell nanoparticles for two different fields of research that is heterogeneous catalysis and water purification. The iron-based core shell materials were characterized by transmission electron microscopy, as well as N2-physisorption, X-ray diffraction, and vibrating-sample magnetometer measurements in order to correlate their properties with the performance in the target applications. Investigations of these materials in CO2 hydrogenation and water purification show their versatility and applicability in different fields of research and application, after suitable individual functionalization of the core-shell precursor. For design and application of magnetically separable particles, the SiO2 shell is surface-functionalized with an ionic liquid in order to bind water pollutants selectively. The core requires no functionalization, as it provides suitable magnetic properties in the as-made state. For catalytic application in synthesis gas reactions, the SiO2-stabilized core nanoparticles are reductively functionalized to provide the catalytically active metallic iron sites. Therefore, Fe@SiO2 core-shell nanostructures are shown to provide platform materials for various fields of application, after a specific functionalization.

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