Ebola virus VP30 is an RNA binding protein

J Virol. 2007 Sep;81(17):8967-76. doi: 10.1128/JVI.02523-06. Epub 2007 Jun 13.

Abstract

The Ebola virus (EBOV) genome encodes for several proteins that are necessary and sufficient for replication and transcription of the viral RNAs in vitro; NP, VP30, VP35, and L. VP30 acts in trans with an RNA secondary structure upstream of the first transcriptional start site to modulate transcription. Using a bioinformatics approach, we identified a region within the N terminus of VP30 with sequence features that typify intrinsically disordered regions and a putative RNA binding site. To experimentally assess the ability of VP30 to directly interact with the viral RNA, we purified recombinant EBOV VP30 to >90% homogeneity and assessed RNA binding by UV cross-linking and filter-binding assays. VP30 is a strongly acidophilic protein; RNA binding became stronger as pH was decreased. Zn(2+), but not Mg(2+), enhanced activity. Enhancement of transcription by VP30 requires a RNA stem-loop located within nucleotides 54 to 80 of the leader region. VP30 showed low binding affinity to the predicted stem-loop alone or to double-stranded RNA but showed a good binding affinity for the stem-loop when placed in the context of upstream and downstream sequences. To map the region responsible for interacting with RNA, we constructed, purified, and assayed a series of N-terminal deletion mutations of VP30 for RNA binding. The key amino acids supporting RNA binding activity map to residues 26 to 40, a region rich in arginine. Thus, we show for the first time the direct interaction of EBOV VP30 with RNA and the importance of the N-terminal region for binding RNA.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites / genetics
  • Coenzymes / pharmacology
  • Computational Biology
  • Ebolavirus / chemistry
  • Ebolavirus / metabolism
  • Hydrogen-Ion Concentration
  • Magnesium / pharmacology
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Protein Binding
  • RNA, Double-Stranded / metabolism
  • RNA, Viral / chemistry
  • RNA, Viral / metabolism*
  • RNA-Binding Proteins / chemistry
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / isolation & purification
  • RNA-Binding Proteins / metabolism*
  • Sequence Deletion
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / isolation & purification
  • Transcription Factors / metabolism*
  • Viral Proteins / chemistry
  • Viral Proteins / genetics
  • Viral Proteins / isolation & purification
  • Viral Proteins / metabolism*
  • Zinc / pharmacology

Substances

  • Coenzymes
  • RNA, Double-Stranded
  • RNA, Viral
  • RNA-Binding Proteins
  • Transcription Factors
  • VP30 protein, ebola virus
  • Viral Proteins
  • Magnesium
  • Zinc