Positively charged residues located downstream of PIP box, together with TD amino acids within PIP box, are important for CRL4(Cdt2) -mediated proteolysis

Genes Cells. 2011 Jan;16(1):12-22. doi: 10.1111/j.1365-2443.2010.01464.x. Epub 2010 Dec 9.


PCNA links Cdt1 and p21 for proteolysis by Cul4-DDB1-Cdt2 (CRL4(Cdt2) ) in the S phase and after DNA damage in mammalian cells. However, other PCNA-interacting proteins, such as ligase I, are not targets of CRL4(Cdt2) . In this study, we created chimera constructs composed of Cdt1 and ligase I and examined how the proteolysis of PCNA-interacting proteins is regulated. Consistent with a recent report using the Xenopus egg system (Havens & Walter 2009), two amino acid elements are also required for degradation in HeLa cells: TD amino acid residues in the PIP box and the basic amino acid at +4 downstream of the PIP box. In addition, we demonstrate that a basic amino acid at +3 is also required for degradation and that an acidic amino acid residue following the basic amino acids abolishes the degradation. Electrostatic surface images suggest that the basic amino acid at +4 is involved in a contact with PCNA, while +3 position extending to opposite direction is important to create a positively charged surface. When all these required elements were introduced in ligase I peptide, the substituted form became degraded. Our results demonstrate that PCNA-dependent degron is strictly composed to avoid illegitimate destruction of PCNA-interacting proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / genetics
  • Amino Acids / metabolism*
  • Animals
  • DNA Damage
  • HeLa Cells
  • Humans
  • Hydrolysis
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Proliferating Cell Nuclear Antigen / genetics
  • Proliferating Cell Nuclear Antigen / metabolism
  • Recombinant Fusion Proteins
  • S Phase
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*
  • Xenopus / genetics
  • Xenopus / metabolism
  • Xenopus laevis / genetics
  • Xenopus laevis / metabolism


  • Amino Acids
  • DTL protein, human
  • Nuclear Proteins
  • Proliferating Cell Nuclear Antigen
  • Recombinant Fusion Proteins
  • Ubiquitin-Protein Ligases