Activity in monomers of human cytomegalovirus protease.
Herpesvirus proteases require dimerization for activity, although crystallographic data indicate that each monomeric subunit possesses a well-separated and complete active site. This suggests that dimerization stabilizes the monomeric protease subunits in an active conformation. Chemical cross-linking with disuccinimidyl glutarate was used to capture human cytomegalovirus protease in its various conformations. The cross-linked protease retained activity under mildly chaotropic conditions (0.25 to 0.75 M urea) in contrast to non-cross-linked protease which lost activity. Identification of active protease species by incorporation of radioactive diisopropylfluorophosphate showed that in addition to cross-linked dimers, cross-linked protease monomers were responsible for a significant fraction of the total protease activity. These results are consistent with the hypothesis that herpesvirus protease activation occurs by stabilization of an active conformer in the dimer.
Holwerda
B
B
Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri 65211, USA. holwerdab@missouri.edu
D001665:Binding Sites; D002213:Capsid / Q000737:chemistry / Q000378:metabolism; D003432:Cross-Linking Reagents; D003587:Cytomegalovirus / Q000201:enzymology*; D019281:Dimerization; D004795:Enzyme Stability; D006801:Humans; D007531:Isoflurophate / Q000378:metabolism; D011487:Protein Conformation; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000378:metabolism; D013388:Succinimides; D014508:Urea / Q000494:pharmacology; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism
D003432:Cross-Linking Reagents; D013388:Succinimides; D014764:Viral Proteins; C096464:disuccinimidyl glutarate; C079287:scaffold protein, Herpes simplex virus-1; D007531:Isoflurophate; D014508:Urea; D012697:Serine Endopeptidases; C071910:assemblin