The Role of the Adenovirus Protease on Virus Entry Into Cells

EMBO J. 1996 Apr 15;15(8):1766-77.


Adenovirus uncoating is a stepwise process which culminates in the release of the viral DNA into the nucleus through the nuclear pore complexes and dissociation of the capsid. Using quantitative biochemical, immunochemical and morphological methods, we demonstrate that inhibitors of the cystine protease, L3/p23, located inside the capsid block the degradation of the capsid-stabilizing protein VI, and prevent virus uncoating at the nuclear membrane. There was no effect on virus internalization, fiber shedding and virus binding to the nuclear envelope. The viral enzyme (dormant in the extracellular virus) was activated by two separate signals, neither of which was sufficient alone; virus interaction with the integrin receptor (inhibited with RGD peptides) and re-entry of the virus particle into a reducing environment in the endosome or the cytosol. Incorrectly assembled mutant viruses that lack the functional protease (ts1) failed at releasing fibers and penetrating into the cytosol. The results indicated that L3/p23 is needed not only to assemble an entry-competent virus but also to disassemble the incoming virus.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenoviruses, Human / enzymology*
  • Adenoviruses, Human / genetics
  • Adenoviruses, Human / physiology
  • Alkylation
  • Amino Acid Sequence
  • Biological Transport, Active
  • Capsid / genetics
  • Capsid / metabolism
  • Capsid Proteins*
  • Cysteine Endopeptidases / chemistry
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / physiology*
  • Dithiothreitol / pharmacology
  • Enzyme Activation
  • Ethylmaleimide / pharmacology
  • HeLa Cells
  • Humans
  • Integrins / antagonists & inhibitors
  • Integrins / physiology
  • Microscopy, Electron
  • Molecular Sequence Data
  • Nuclear Envelope / ultrastructure
  • Nuclear Envelope / virology
  • Oligopeptides / chemistry
  • Oligopeptides / pharmacology
  • Sulfhydryl Compounds / chemistry
  • Sulfhydryl Reagents / pharmacology
  • Viral Proteins*


  • Capsid Proteins
  • Integrins
  • Oligopeptides
  • Sulfhydryl Compounds
  • Sulfhydryl Reagents
  • Viral Proteins
  • polypeptide VI, adenovirus
  • arginyl-glycyl-aspartic acid
  • Cysteine Endopeptidases
  • L3 23K protein, adenovirus
  • Ethylmaleimide
  • Dithiothreitol