Biomedical subjects

Bettina Hartlieb

Publications and source records attributed to Bettina Hartlieb.

4 recordsLinked to original sources

PubMed2007

Crystal structure of the C-terminal domain of Ebola virus VP30 reveals a role in transcription and nucleocapsid association.

Transcription of the highly pathogenic Ebola virus depends on VP30, a nucleocapsid-associated Ebola virus-specific transcription factor. The transcription activator VP30 was shown to play an essential role in Ebola virus replication, most likely by stabilizing nascent mRNA. Here we present the crystal structure of the C-terminal domain (CTD) of VP30 (VP30(CTD)) at 2.0-A resolution. VP30(CTD) folds independently into a dimeric helical assembly. The VP30(CTD) dimers assemble into hexamers that are present in virions, by an oligomerization domain located in the N terminus of VP30. Mutagenesis of conserved charged amino acids on VP30(CTD) revealed that two regions, namely a basic cluster around Lys-180 and Glu-197, are required for nucleocapsid interaction. However, only mutagenesis of the basic cluster was shown to impair transcription activation, suggesting that both processes are regulated independently. The structure and the mutagenesis results reveal a potential pocket for small-molecule inhibitors that might prevent VP30 activity and thus virus propagation as it has been shown previously by peptides, which interfere with VP30 homooligomerization.

Amino Acid Substitution↗

PubMed2006

Filovirus assembly and budding.

Filoviruses belong to the order of negative-stranded non-segmented RNA viruses and are classified into two genera, Ebola and Marburg viruses. They have a characteristic filamentous shape, which is largely determined by the matrix protein VP40. Although VP40 is the main driving force for assembly and budding from the host cell, the production of infectious virus involves an intricate interplay between all viral structural proteins in addition to cellular factors, e.g., those that normally function in multi-vesicular body biogenesis. As a consequence, assembly and budding steps are defined to specific cellular compartments, and the recent progress in understanding how the different components are assembled into stable enveloped virus particles is reviewed.

Animals↗

PubMed2006

Infection of naive target cells with virus-like particles: implications for the function of ebola virus VP24.

Infectious virus-like particle (iVLP) systems have recently been established for several negative-strand RNA viruses, including the highly pathogenic Zaire ebolavirus (ZEBOV), and allow study of the viral life cycle under biosafety level 2 conditions. However, current systems depend on the expression of viral helper nucleocapsid proteins in target cells, thus making it impossible to determine whether ribonucleoprotein complexes transferred by iVLPs are able to facilitate initial transcription, an indispensable step in natural infection. Here we describe a ZEBOV iVLP system which overcomes this limitation and show that VP24 is essential for the formation of a functional ribonucleoprotein complex.

Animals↗

PubMed2003

Oligomerization of Ebola virus VP30 is essential for viral transcription and can be inhibited by a synthetic peptide.

Transcription of Ebola virus (EBOV)-specific mRNA is driven by the nucleocapsid proteins NP, VP35, and L. This process is further dependent on VP30, an essential EBOV-specific transcription factor. The present study addresses the self-assembly of VP30 and the functional significance of this process for viral transcription and propagation. Essential for oligomerization of VP30 is a region spanning amino acids 94-112. Within this region a cluster of four leucine residues is of critical importance. Mutation of only one of these leucine residues resulted in oligomerization-deficient VP30 molecules that were no longer able to support EBOV-specific transcription. The essential role of homo-oligomerization for the function of VP30 was further corroborated by the finding that mixed VP30 oligomers consisting of VP30 and transcriptionally inactive VP30 mutants were impaired in their ability to support EBOV transcription. The dominant negative effect of these VP30 mutants was dependent on their ability to bind to VP30. The oligomerization of VP30 could be dose dependently inhibited by a 25-mer peptide (E30pep-wt) derived from the presumed oligomerization domain (IC50,1 mum). A control peptide (E30pep-3LA), in which three leucines were changed to alanine, had no inhibitory effect. Thus, E30pep-wt seemed to bind efficiently to VP30 and consequently blocked the oligomerization of the protein. When E30pep-wt was transfected into EBOV-infected cells, the peptide inhibited viral replication suggesting that inhibition of VP30 oligomerization represents a target for EBOV antiviral drugs.

Amino Acid Sequence↗