scholarly journals Atomic structures and deletion mutant reveal different capsid-binding patterns and functional significance of tegument protein pp150 in murine and human cytomegaloviruses with implications for therapeutic development

2019 ◽  
Vol 15 (2) ◽  
pp. e1007615 ◽  
Author(s):  
Wei Liu ◽  
Xinghong Dai ◽  
Jonathan Jih ◽  
Karen Chan ◽  
Phong Trang ◽  
...  
Keyword(s):  
Functional Significance ◽  
Deletion Mutant ◽  
Tegument Protein ◽  
Atomic Structures ◽  
Therapeutic Development

scholarly journals Different capsid-binding patterns of the β-herpesvirus-specific tegument protein pp150 (pM32/pUL32) in murine and human cytomegaloviruses

2018 ◽  
Author(s):  
Wei Liu ◽  
Xinghong Dai ◽  
Jonathan Jih ◽  
Karen Chan ◽  
Phong Trang ◽  
...  
Keyword(s):  
Therapeutic Strategies ◽  
Capsid Proteins ◽  
Tegument Protein ◽  
Cmv Infection ◽  
Mcmv Infection ◽  
Atomic Structures ◽  
Functional Studies ◽  
Congenital Birth Defects ◽  
Human Cmv ◽  
Human And Mouse

AbstractThe phosphoprotein pp150 is a structurally, immunogenically, and regulatorily important capsid-associated tegument protein abundant in β-herpesviruses including cytomegaloviruses (CMV), but absent in α-herpesviruses and Γ-herpesviruses. In human CMV (HCMV), bridging across each triplex and three adjacent major capsid proteins (MCPs) is a group of three pp150 subunits in a “△”-shapedfortifyingconfiguration, 320 of which encase and stabilize the genome-containing capsid. Because murine CMV (MCMV) has been used as a model for HCMV pathogenesis and therapeutic studies, one might expect that pp150 and the capsid in MCMV and HCMV have similar structures. Here, by cryoEM and sub-particle reconstructions, we have obtained structures of MCMV capsid and pp150 at near atomic resolutions and built their atomic models. Surprisingly, the capsid-binding patterns of pp150 differ between HCMV and MCMV despite their highly similar capsid structures. In MCMV, pp150 is absent on triplex Tc and exists as a “Λ”-shaped dimer on other triplexes, leading to only 260 groups of two pp150 subunits per capsid in contrast to 320 groups of three pp150 subunits encasing each HCMV capsid. Many more amino acids contribute to pp150-pp150 interactions in MCMV than in HCMV, making MCMV pp150 dimer inflexible thus incompatible to instigate triplex Tc-binding as observed in HCMV. While pp150 is essential in HCMV, pp150-deleted MCMV mutants remained viable though with attenuated infectivity and exhibiting defects in retaining viral genome. These results support targeting capsid proteins, but invalidate targeting pp150, when using MCMV as a model for HCMV pathogenesis and therapeutic studies.ImportanceCMV infection is a leading viral cause of congenital birth defects and often responsible for life-threating complications in immunocompromised individuals like AIDS and post-organ transplantation patients. Absence of effective vaccines and potent drugs against CMV infections has motivated animal-based studies, mostly based on the mouse model with MCMV, both for understanding pathogenesis of CMV infections and for developing therapeutic strategies. Here, we present the first atomic structures of MCMV and show that the organization patterns of capsid-associated tegument protein pp150 between human and mouse CMV are different despite their highly similar capsid structures. Our functional studies demonstrate that deleting pp150 does not eliminate MCMV infection in contrast to pp150’s essential role in HCMV infections. These results thus establish the validity to target capsid proteins, but raise concerns to target pp150, when using MCMV as HCMV model for pathogenesis and therapeutic studies.

scholarly journals UL26-Deficient Human Cytomegalovirus Produces Virions with Hypophosphorylated pp28 Tegument Protein That Is Unstable within Newly Infected Cells

2006 ◽  
Vol 80 (7) ◽  
pp. 3541-3548 ◽  
Author(s):  
Joshua Munger ◽  
Dong Yu ◽  
Thomas Shenk
Keyword(s):  
Human Cytomegalovirus ◽  
Deletion Mutant ◽  
Open Reading Frame ◽  
Early Gene ◽  
Immediate Early ◽  
Tegument Protein ◽  
Protein Accumulation ◽  
Reading Frame ◽  
Tegument Proteins ◽  
Infected Cells

ABSTRACT The human cytomegalovirus UL26 open reading frame encodes proteins of 21 and 27 kDa that result from the use of two different in-frame initiation codons. The UL26 protein is a constituent of the virion and thus is delivered to cells upon viral entry. We have characterized a mutant of human cytomegalovirus in which the UL26 open reading frame has been deleted. The UL26 deletion mutant has a profound growth defect, the magnitude of which is dependent on the multiplicity of infection. Two very early defects were discovered. First, even though they were present in normal amounts within mutant virions, the UL99-coded pp28 and UL83-coded pp65 tegument proteins were present in reduced amounts at the earliest times assayed within newly infected cells; second, there was a delay in immediate-early mRNA and protein accumulation. Further analysis revealed that although wild-type levels of the pp28 tegument protein were present in UL26 deletion mutant virions, the protein was hypophosphorylated. We conclude that the UL26 protein influences the normal phosphorylation of at least pp28 in virions and possibly additional tegument proteins. We propose that the hypophosphorylation of tegument proteins causes their destabilization within newly infected cells, perhaps disrupting the normal detegumentation process and leading to a delay in the onset of immediate-early gene expression.

scholarly journals Bovine Herpesvirus 1 Tegument Protein VP22 Interacts with Histones, and the Carboxyl Terminus of VP22 Is Required for Nuclear Localization

2001 ◽  
Vol 75 (17) ◽  
pp. 8251-8258 ◽  
Author(s):  
Xiaodi Ren ◽  
Jerome S. Harms ◽  
Gary A. Splitter
Keyword(s):  
Nuclear Localization ◽  
Deletion Mutant ◽  
Bovine Herpesvirus ◽  
Mutant Virus ◽  
Tegument Protein ◽  
Carboxyl Terminus ◽  
Slight Reduction ◽  
Bovine Herpesvirus 1 ◽  
Herpesvirus 1

ABSTRACT The bovine herpesvirus 1 (BHV-1) UL49 gene encodes a viral tegument protein termed VP22. UL49 homologs are conserved among alphaherpesviruses. Interestingly, the BHV-1 VP22 deletion mutant virus is asymptomatic and avirulent in infected cattle but produces only a slight reduction in titer in vitro. Attenuation of the BHV-1 VP22 deletion mutant virus in vivo suggests that VP22 plays a functional role in BHV-1 replication. In herpes simplex virus type 1, the VP22 homolog was previously shown to interact with another tegument protein,VP16, the α-transinducing factor in vitro. In this report, we show that (i) the nuclear targeting of VP22 is independent of other viral factors, (ii) the carboxyl terminus of VP22 is required for its nuclear localization, (iii) VP22 associates with histones and nucleosomes, (iv) an antihistone monoclonal antibody cross-reacts with VP22, and (v) acetylation of histone H4 is decreased in VP22-expressing cells as well as virus-infected cells. Our data suggest that VP22 may have a modulatory function during BHV-1 infection.

Functional significance of preserved color patterns of mollusks from the Gosport Sand (Eocene) of Alabama

1988 ◽  
Vol 62 (01) ◽  
pp. 83-87 ◽  
Author(s):  
Patricia H. Kelley ◽  
Charles T. Swann
Keyword(s):  
Functional Morphology ◽  
Functional Significance ◽  
Intraspecific Variability ◽  
Color Pattern ◽  
Color Patterns ◽  
Historical Factors ◽  
Life Mode ◽  
Molluscan Fauna ◽  
Excellent Preservation ◽  
Architectural Constraints

The excellent preservation of the molluscan fauna from the Gosport Sand (Eocene) at Little Stave Creek, Alabama, has made it possible to describe the preserved color patterns of 15 species. In this study the functional significance of these color patterns is tested in the context of the current adaptationist controversy. The pigment of the color pattern is thought to be a result of metabolic waste disposal. Therefore, the presence of the pigment is functional, although the patterns formed by the pigment may or may not have been adaptive. In this investigation the criteria proposed by Seilacher (1972) for testing the functionality of color patterns were applied to the Gosport fauna and the results compared with life mode as interpreted from knowledge of extant relatives and functional morphology. Using Seilacher's criteria of little ontogenetic and intraspecific variability, the color patterns appear to have been functional. However, the functional morphology studies indicate an infaunal life mode which would preclude functional color patterns. Particular color patterns are instead interpreted to be the result of historical factors, such as multiple adaptive peaks or random fixation of alleles, or of architectural constraints including possibly pleiotropy or allometry. The low variability of color patterns, which was noted within species and genera, suggests that color patterns may also serve a useful taxonomic purpose.

Finding the Right Problems: Some HREM Applications to Interfaces

1984 ◽  
Vol 42 ◽  
pp. 376-379
Author(s):  
D. Cherns
Keyword(s):  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Boundary Structure ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Resolution Electron ◽  
Point To Point ◽  
The Right ◽  
New Generation ◽  
Better Than

The use of high resolution electron microscopy (HREM) to determine the atomic structure of grain boundaries and interfaces is a topic of great current interest. Grain boundary structure has been considered for many years as central to an understanding of the mechanical and transport properties of materials. Some more recent attention has focussed on the atomic structures of metalsemiconductor interfaces which are believed to control electrical properties of contacts. The atomic structures of interfaces in semiconductor or metal multilayers is an area of growing interest for understanding the unusual electrical or mechanical properties which these new materials possess. However, although the point-to-point resolutions of currently available HREMs, ∼2-3Å, appear sufficient to solve many of these problems, few atomic models of grain boundaries and interfaces have been derived. Moreover, with a new generation of 300-400kV instruments promising resolutions in the 1.6-2.0 Å range, and resolutions better than 1.5Å expected from specialist instruments, it is an appropriate time to consider the usefulness of HREM for interface studies.

Complex Vesicles, Microtubules, and Cytoplasmic Filaments in the Endothelial Cells of Normal Dog Aorta

1968 ◽  
Vol 26 ◽  
pp. 172-173
Author(s):  
C. N. Sun ◽  
J. J. Ghidoni
Keyword(s):  
Electron Microscopy ◽  
Endothelial Cells ◽  
Cross Sections ◽  
Functional Significance ◽  
Tubular Structures ◽  
Aldehyde Fixation ◽  
Cytoplasmic Filaments

Endothelial cells in longitudinal and cross sections of aortas from 3 randomly selected “normal” mongrel dogs were studied by electron microscopy. Segments of aorta were distended with cold cacodylate buffered 5% glutaraldehyde for 10 minutes prior to being cut into small, well oriented tissue blocks. After an additional 1-1/2 hour period in glutaraldehyde, the tissue blocks were well rinsed in buffer and post-fixed in OsO4. After dehydration they were embedded in a mixture of Maraglas, D.E.R. 732, and DDSA.Aldehyde fixation preserves the filamentous and tubular structures (300 Å and less) for adequate demonstration and study. The functional significance of filaments and microtubules has been recently discussed by Buckley and Porter; the precise roles of these cytoplasmic components remains problematic. Endothelial cells in canine aortas contained an abundance of both types of structures.

Quasiperiodic interfaces: HREM observations of grain and phase boundaries

1990 ◽  
Vol 48 (4) ◽  
pp. 332-333
Author(s):  
K. L. Merkle
Keyword(s):  
Atomic Structure ◽  
Direct Determination ◽  
Lattice Parameter ◽  
Atomic Scale ◽  
Misfit Dislocations ◽  
Oxide Systems ◽  
Atomic Structures ◽  
Periodic Arrays ◽  
Parameter Ratio ◽  
Metal Metal

The atomic structures of internal interfaces have recently received considerable attention, not only because of their importance in determining many materials properties, but also because the atomic structure of many interfaces has become accessible to direct atomic-scale observation by modem HREM instruments. In this communication, several interface structures are examined by HREM in terms of their structural periodicities along the interface.It is well known that heterophase boundaries are generally formed by two low-index planes. Often, as is the case in many fcc metal/metal and metal/metal-oxide systems, low energy boundaries form in the cube-on-cube orientation on (111). Since the lattice parameter ratio between the two materials generally is not a rational number, such boundaries are incommensurate. Therefore, even though periodic arrays of misfit dislocations have been observed by TEM techniques for numerous heterophase systems, such interfaces are quasiperiodic on an atomic scale. Interfaces with misfit dislocations are semicoherent, where atomically well-matched regions alternate with regions of misfit. When the misfit is large, misfit localization is often difficult to detect, and direct determination of the atomic structure of the interface from HREM alone, may not be possible.

Flux-pinning-related defect structures in melt-processed YBa2Cu3O7-x

1993 ◽  
Vol 51 ◽  
pp. 936-937
Author(s):  
Z. L. Wang ◽  
R. Kontra ◽  
A. Goyal ◽  
D. M. Kroeger ◽  
L.F. Allard
Keyword(s):  
Volume Fraction ◽  
Local Density ◽  
Stacking Faults ◽  
Image Resolution ◽  
Defect Structures ◽  
Atomic Structures ◽  
Transmission Electron ◽  
Point Image ◽  
Related Defect ◽  
Point To Point

Previous studies of Y2BaCuO5/YBa2Cu3O7-δ(Y211/Y123) interfaces in melt-processed and quench-melt-growth processed YBa2Cu3O7-δ using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) have revealed a high local density of stacking faults in Y123, near the Y211/Y123 interfaces. Calculations made using simple energy considerations suggested that these stacking faults may act as effective flux-pinners and may explain the observations of increased Jc with increasing volume fraction of Y211. The present paper is intended to determine the atomic structures of the observed defects. HRTEM imaging was performed using a Philips CM30 (300 kV) TEM with a point-to-point image resolution of 2.3 Å. Nano-probe EDS analysis was performed using a Philips EM400 TEM/STEM (100 kV) equipped with a field emission gun (FEG), which generated an electron probe of less than 20 Å in diameter.Stacking faults produced by excess single Cu-O layers: Figure 1 shows a HRTEM image of a Y123 film viewed along [100] (or [010]).

High-Resolution Image Simulation of a Tilted Crystal

1990 ◽  
Vol 48 (1) ◽  
pp. 68-69
Author(s):  
C. J. D. Hetherington
Keyword(s):  
High Resolution ◽  
Crystal Thickness ◽  
Thin Specimen ◽  
Atomic Structures ◽  
Kikuchi Lines ◽  
High Resolution Images ◽  
Final Estimate ◽  
Simulated Images ◽  
Habit Planes

Most high resolution images are not directly interpretable but must be compared with simulations based on model atomic structures and appropriate imaging conditions. Typically, the only parameters that are adjusted, in addition to the structure models, are crystal thickness and microscope defocus. Small tilts of the crystal away from the exact zone axis have only rarely been considered. It is shown here that, in the analysis of an image of a silicon twin intersection, the crystal tilt could be accurately estimated and satisfactorily included in the simulations.The micrograph shown in figure 1 was taken as part of an HREM study of indentation-induced hexagonal silicon. In this instance, the intersection of two twins on different habit planes has driven the silicon into hexagonal stacking. However, in order to confirm this observation, and in order to investigate other defects in the region, it has been necessary to simulate the image taking into account the very apparent crystal tilt. The inability to orientate the specimen at the exact [110] zone was influenced by i) the buckling of the specimen caused by strains at twin intersections, ii) the absence of Kikuchi lines or a clearly visible Laue circle in the diffraction pattern of the thin specimen and iii) the avoidance of radiation damage (which had marked effects on images taken a few minutes later following attempts to realign the crystal.) The direction of the crystal tilt was estimated by observing which of the {111} planes remained close to edge-on to the beam and hence strongly imaged. Further refinement of the direction and magnitude of the tilt was done by comparing simulated images to experimental images in a through-focal series. The presence of three different orientations of the silicon lattice aided the unambiguous determination of the tilt. The final estimate of a 0.8° tilt in the 200Å thick specimen gives atomic columns a projected width of about 3Å.

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