70 research outputs found
Tunable single-photon ionization TOF mass spectrometry using laser-produced plasma as the table-top VUV light source
Structure and Functional Analysis of the RNA- and Viral Phosphoprotein-Binding Domain of Respiratory Syncytial Virus M2-1 Protein
Respiratory syncytial virus (RSV) protein M2-1 functions as an essential transcriptional cofactor of the viral RNA-dependent RNA polymerase (RdRp) complex by increasing polymerase processivity. M2-1 is a modular RNA binding protein that also interacts with the viral phosphoprotein P, another component of the RdRp complex. These binding properties are related to the core region of M2-1 encompassing residues S58 to K177. Here we report the NMR structure of the RSV M2-158–177 core domain, which is structurally homologous to the C-terminal domain of Ebola virus VP30, a transcription co-factor sharing functional similarity with M2-1. The partial overlap of RNA and P interaction surfaces on M2-158–177, as determined by NMR, rationalizes the previously observed competitive behavior of RNA versus P. Using site-directed mutagenesis, we identified eight residues located on these surfaces that are critical for an efficient transcription activity of the RdRp complex. Single mutations of these residues disrupted specifically either P or RNA binding to M2-1 in vitro. M2-1 recruitment to cytoplasmic inclusion bodies, which are regarded as sites of viral RNA synthesis, was impaired by mutations affecting only binding to P, but not to RNA, suggesting that M2-1 is associated to the holonucleocapsid by interacting with P. These results reveal that RNA and P binding to M2-1 can be uncoupled and that both are critical for the transcriptional antitermination function of M2-1
Effects of Aversive Stimuli on Prospective Memory. An Event-Related fMRI Study
Prospective memory (PM) describes the ability to execute a previously planned action at the appropriate point in time. Although behavioral studies clearly showed that prospective memory performance is affected by the emotional significance attributed to the intended action, no study so far investigated the brain mechanisms subserving the modulatory effect of emotional salience on PM performance. The general aim of the present study was to explore brain regions involved in prospective memory processes when PM cues are associated with emotional stimuli. In particular, based on the hypothesised critical role of the prefrontal cortex in prospective memory in the presence of emotionally salient stimuli, we expected a stronger involvement of aPFC when the retrieval and execution of the intended action is cued by an aversive stimulus. To this aim BOLD responses of PM trials cued by aversive facial expressions were compared to PM trials cued by neutral facial expressions. Whole brain analysis showed that PM task cued by aversive stimuli is differentially associated with activity in the right lateral prefrontal area (BA 10) and in the left caudate nucleus. Moreover a temporal shift between the response of the caudate nucleus that preceded that of aPFC was observed. These findings suggest that the caudate nucleus might provide an early analysis of the affective properties of the stimuli, whereas the anterior lateral prefrontal cortex (BA10) would be involved in a slower and more deliberative analysis to guide goal-directed behaviour
Virus nomenclature below the species level : a standardized nomenclature for filovirus strains and variants rescued from cDNA
Specific alterations (mutations, deletions,
insertions) of virus genomes are crucial for the functional
characterization of their regulatory elements and their expression products, as well as a prerequisite for the creation
of attenuated viruses that could serve as vaccine
candidates. Virus genome tailoring can be performed either
by using traditionally cloned genomes as starting materials,
followed by site-directed mutagenesis, or by de novo synthesis
of modified virus genomes or parts thereof. A systematic
nomenclature for such recombinant viruses is
necessary to set them apart from wild-type and laboratoryadapted
viruses, and to improve communication and collaborations
among researchers who may want to use
recombinant viruses or create novel viruses based on them.
A large group of filovirus experts has recently proposed
nomenclatures for natural and laboratory animal-adapted
filoviruses that aim to simplify the retrieval of sequence
data from electronic databases. Here, this work is extended
to include nomenclature for filoviruses obtained in the
laboratory via reverse genetics systems. The previously
developed template for natural filovirus genetic variant
naming,\virus name[(\strain[/)\isolation host-suffix[/
\country of sampling[/\year of sampling[/\genetic
variant designation[-\isolate designation[, is retained, but we propose to adapt the type of information added to each
field for cDNA clone-derived filoviruses. For instance, the
full-length designation of an Ebola virus Kikwit variant
rescued from a plasmid developed at the US Centers for
Disease Control and Prevention could be akin to ‘‘Ebola
virus H.sapiens-rec/COD/1995/Kikwit-abc1’’ (with the
suffix ‘‘rec’’ identifying the recombinant nature of the virus
and ‘‘abc1’’ being a placeholder for any meaningful isolate
designator). Such a full-length designation should be used
in databases and the methods section of publications.
Shortened designations (such as ‘‘EBOV H.sap/COD/95/
Kik-abc1’’) and abbreviations (such as ‘‘EBOV/Kik-abc1’’)
could be used in the remainder of the text, depending on
how critical it is to convey information contained in the
full-length name. ‘‘EBOV’’ would suffice if only one
EBOV strain/variant/isolate is addressed.http://link.springer.com/journal/705hb201
2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.
In March 2021, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by four families (Aliusviridae, Crepuscuviridae, Myriaviridae, and Natareviridae), three subfamilies (Alpharhabdovirinae, Betarhabdovirinae, and Gammarhabdovirinae), 42 genera, and 200 species. Thirty-nine species were renamed and/or moved and seven species were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV
Structural dissection of Ebola virus and its assembly determinants using cryo-electron tomography
Ebola virus is a highly pathogenic filovirus causing severe hemorrhagic fever with high mortality rates. It assembles heterogenous, filamentous, enveloped virus particles containing a negative-sense, single-stranded RNA genome packaged within a helical nucleocapsid (NC). We have used cryo-electron microscopy and tomography to visualize Ebola virus particles, as well as Ebola virus-like particles, in three dimensions in a near-native state. The NC within the virion forms a left-handed helix with an inner nucleoprotein layer decorated with protruding arms composed of VP24 and VP35. A comparison with the closely related Marburg virus shows that the N-terminal region of nucleoprotein defines the inner diameter of the Ebola virus NC, whereas the RNA genome defines its length. Binding of the nucleoprotein to RNA can assemble a loosely coiled NC-like structure; the loose coil can be condensed by binding of the viral matrix protein VP40 to the C terminus of the nucleoprotein, and rigidified by binding of VP24 and VP35 to alternate copies of the nucleoprotein. Four proteins (NP, VP24, VP35, and VP40) are necessary and sufficient to mediate assembly of an NC with structure, symmetry, variability, and flexibility indistinguishable from that in Ebola virus particles released from infected cells. Together these data provide a structural and architectural description of Ebola virus and define the roles of viral proteins in its structure and assembl
Value and limitations of computed tomography in assessing aortocoronary bypass graft patency.
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