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Processing of a pestivirus protein by a cellular protease specific for light chain 3 of microtubule-associated

Jens Fricke1, Christiane Voss, Michael Thumm

  • 1Institut für Immunologie, Federal Research Center for Virus Diseases of Animals, P.O. Box 1149, D-72001 Tübingen, Germany.

Journal of Virology
|May 14, 2004
PubMed

Insights

Bovine viral diarrhea virus (BVDV) uses a cellular light chain 3 (LC3) protein insertion for replication. This LC3 insertion requires specific protease processing, essential for viral viability and demonstrating conserved evolutionary mechanisms.

Area of Science:

  • Virology
  • Molecular Biology
  • Protease Function

Background:

  • Cytopathogenic bovine viral diarrhea virus (BVDV) JaCP possesses a unique genome.
  • This genome includes a cellular light chain 3 (LC3) insertion, a mammalian homolog of yeast Aut7p/Apg8p.
  • This LC3 insertion is processed by a cellular cysteine protease similar to yeast Aut2p/Apg4p.

Purpose of the Study:

  • To identify and functionally characterize bovine proteases involved in processing the BVDV LC3 insertion.
  • To investigate the evolutionary conservation of the LC3 processing pathway.
  • To determine the essentiality of LC3-specific processing for BVDV replication.

Main Methods:

  • Sequence similarity searches identified candidate bovine protease genes.
  • Functional assays were performed using various cell lines, rabbit reticulocyte lysate, and yeast deletion mutants.
  • Coexpression experiments and Northern blot analysis were utilized.

Main Results:

  • Three candidate bovine proteases homologous to yeast Aut2p/Apg4p were identified.
  • The LC3 processing system is highly conserved across mammalian, avian, fish, and insect cells.
  • Bovine and chicken proteases could rescue yeast AUT2 deletion mutants and process the viral polyprotein.
  • LC3-specific processing of the viral polyprotein is critical for BVDV replication; mutants affecting this process were non-viable.

Conclusions:

  • Bovine viral diarrhea virus utilizes a host cell protein (LC3) and a conserved protease system for its replication.
  • The identified bovine proteases and their homologs play a crucial role in viral polyprotein processing.
  • Disruption of the LC3-specific processing pathway leads to non-viable BVDV mutants, highlighting its essentiality.

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