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Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production
08:32

Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production

Published on: March 2, 2014

The murine endogenous retrovirus MIA14 encodes an active aspartic proteinase that is functionally similar to

Kvido Strísovský1, Daniel Smrz, Frauke Fehrmann

  • 1Department of Biochemistry, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, Praha 6, 166 10, Czech Republic. strisovk@uochb.cas.cz

Archives of Biochemistry and Biophysics
|February 8, 2002
PubMed

Insights

Murine intracisternal A-type particles (IAPs) possess a functional viral proteinase (PR) capable of polyprotein processing. This finding suggests a role for PR in the intracellular retrotransposition of endogenous retroviruses.

Area of Science:

  • Retroviral biology
  • Molecular virology
  • Endogenous retroviruses

Background:

  • Murine intracisternal A-type particles (IAPs) are endogenous retroviruses with similarities to B/D- and avian C-type retroviruses.
  • IAPs form immature particles and are retrotransposition-competent within the cell, but lack extracellular virion release.
  • Previous assumptions suggested a defective viral proteinase (PR) caused the lack of polyprotein processing and maturation.

Purpose of the Study:

  • To investigate the catalytic activity and processing capabilities of the MIA14 IAP viral proteinase (PR).
  • To compare the MIA14 PR with other retroviral proteases, including HIV-1 PR and type D retroviral PRs.
  • To elucidate the functional and evolutionary relationship between MIA14 and D-type retroviruses.

Main Methods:

  • Expression and purification of recombinant MIA14 PR.
  • Analysis of MIA14 PR N- and C-terminal autoprocessing.
  • In vitro cleavage assays using peptide substrates and recombinant MIA14 and HIV-1 Gag polyproteins.
  • Enzyme inhibition assays.

Main Results:

  • Recombinant MIA14 PR undergoes efficient N- and C-terminal autoprocessing at specific sites.
  • MIA14 PR is catalytically competent, with efficiency comparable to type D exogenous retroviral PRs.
  • MIA14 PR exhibits distinct substrate specificity and catalytic efficiency compared to HIV-1 PR.

Conclusions:

  • The MIA14 PR is a functional enzyme, challenging previous assumptions about its defectiveness.
  • MIA14 PR shares functional and potentially evolutionary links with type D retroviruses.
  • A functional PR may be crucial for intracellular retrotransposition in endogenous retroviruses lacking extracellular release.

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