Dual short upstream open reading frames control translation of a herpesviral polycistronic mRNA

PLoS Pathog. 2013 Jan;9(1):e1003156. doi: 10.1371/journal.ppat.1003156. Epub 2013 Jan 31.

Abstract

The Kaposi's sarcoma-associated herpesvirus (KSHV) protein kinase, encoded by ORF36, functions to phosphorylate cellular and viral targets important in the KSHV lifecycle and to activate the anti-viral prodrug ganciclovir. Unlike the vast majority of mapped KSHV genes, no viral transcript has been identified with ORF36 positioned as the 5'-proximal gene. Here we report that ORF36 is robustly translated as a downstream cistron from the ORF35-37 polycistronic transcript in a cap-dependent manner. We identified two short, upstream open reading frames (uORFs) within the 5' UTR of the polycistronic mRNA. While both uORFs function as negative regulators of ORF35, unexpectedly, the second allows for the translation of the downstream ORF36 gene by a termination-reinitiation mechanism. Positional conservation of uORFs within a number of related viruses suggests that this may be a common γ-herpesviral adaptation of a host translational regulatory mechanism.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions / genetics
  • Base Sequence
  • Cell Line
  • Gene Expression Regulation, Viral*
  • Herpesvirus 8, Human / genetics*
  • Humans
  • Molecular Sequence Data
  • Multigene Family
  • Open Reading Frames / genetics*
  • Protein Biosynthesis
  • RNA, Messenger / genetics*
  • RNA, Viral / chemistry
  • RNA, Viral / genetics*
  • Sequence Homology, Nucleic Acid
  • Transcription, Genetic

Substances

  • 5' Untranslated Regions
  • RNA, Messenger
  • RNA, Viral