Prb1 Protease Activity Is Required for Its Recognition by the F-Box Protein Saf1

Biochemistry. 2015 Jul 28;54(29):4423-6. doi: 10.1021/acs.biochem.5b00504. Epub 2015 Jul 17.


The SCF ubiquitin ligase associates with substrates through its F-box protein adaptor. Substrates are typically recognized through a defined phosphodegron. Here, we characterize the interaction of the F-box protein Saf1 with Prb1, one of its vacuolar protease substrates. We show that Saf1 binds the mature protein but ubiquitinates only the zymogen precursor. The ubiquitinated lysine was found to be in a peptide eliminated from the mature protein. Mutations that eliminate the catalytic activity of Prb1, or the related substrate Prc1, block Saf1 targeting of the zymogen precursor. Our data suggest that Saf1 does not require a conventional degron as do other F-box proteins but instead recognizes the catalytic site itself.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Endopeptidases / chemistry*
  • Endopeptidases / physiology
  • F-Box Proteins / chemistry*
  • Protein Binding
  • Proteolysis
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / physiology


  • F-Box Proteins
  • Saccharomyces cerevisiae Proteins
  • Saf1 protein, S cerevisiae
  • Endopeptidases
  • PRB1 protein, S cerevisiae