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Gene overlap results in a viral protein having an RNA binding domain and a major coat protein domain

T Fujimura1, R B Wickner

  • 1Section on Genetics of Simple Eukaryotes, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.

Cell
|November 18, 1988
PubMed

Insights

Researchers discovered that a specific protein in yeast virus-like particles (VLPs) binds single-stranded RNA (ssRNA) and is essential for replicating double-stranded RNA (dsRNA). This protein is encoded by the L-A dsRNA genome.

Area of Science:

  • Molecular Virology
  • Yeast Genetics
  • RNA Replication

Background:

  • L-A double-stranded RNA (dsRNA) replicates within yeast virus-like particles (VLPs) through a conservative, asynchronous process.
  • New viral particles are assembled by packaging newly synthesized (+) strands.

Purpose of the Study:

  • To investigate the mechanism of L-A dsRNA replication and particle formation in yeast.
  • To identify host factors and viral proteins involved in RNA binding and replication within VLPs.

Main Methods:

  • In vitro conversion of viral (+) single-stranded RNA (ssRNA) to dsRNA using isolated VLPs and a host factor.
  • Analysis of ssRNA binding activity of VLP proteins using Western blots.
  • Immunological comparison of the 180 kDa protein with the major coat protein and L-A (+) strand sequences.

Main Results:

  • Empty VLPs specifically bind viral (+) ssRNA, and this binding, with a host factor, leads to dsRNA synthesis in vitro.
  • The isolated binding complex replicates only if formed in the presence of the host factor.
  • The VLP minor 180 kDa protein exhibits ssRNA binding activity and shares antigenic domains with the major coat protein and the L-A (+) strand, indicating it is also encoded by L-A dsRNA.

Conclusions:

  • The L-A dsRNA genome encodes a 180 kDa protein with both a major coat protein domain and an ssRNA binding domain.
  • This 180 kDa protein is crucial for the specific binding of ssRNA and subsequent dsRNA replication within yeast VLPs, requiring a host factor.

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