title: A 39 amino acid fragment of the cell cycle regulator p21 is sufficient to bind PCNA and partially inhibit DNA replication in vivo.
abstract: The cell cycle regulator p21 interacts with and inhibits the DNA replication and repair factor proliferating cell nuclear antigen (PCNA). We have defined a 39 amino acid fragment of p21 which is sufficient to bind PCNA with high affinity (Kd 10-20 nM). This peptide can inhibit DNA replication in vitro and microinjection of a GST fusion protein containing this domain inhibited S phase in vivo. Despite its high affinity for PCNA, the free 39 amino acid peptide does not have a well-defined structure, as judged from circular dichroism and nuclear magnetic resonance measurements, suggesting an induced fit mechanism for the PCNA-p21 interaction. The association of the small peptide with PCNA was thermolabile, suggesting that portions of p21 adjoining the minimal region of contact stabilize the interaction. In addition, a domain containing 67 amino acids from the N-terminus of PCNA was defined as both necessary and sufficient for binding to p21.
authors.affiliation: Department of Pathology, Division of Molecular Oncology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: R
authors.initials: R
authors.lastname: Peters
authors.forename: P
authors.initials: P
authors.lastname: Saha
authors.forename: P
authors.initials: P
authors.lastname: Lee
authors.forename: A
authors.initials: A
authors.lastname: Theodoras
authors.forename: M
authors.initials: M
authors.lastname: Pagano
authors.forename: G
authors.initials: G
authors.lastname: Wagner
authors.forename: A
authors.initials: A
authors.lastname: Dutta
mesh_terms: D000595:Amino Acid Sequence; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D016213:Cyclins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D004261:DNA Replication / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors; D005347:Fibroblasts; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D016196:S Phase / Q000187:drug effects; D017384:Sequence Deletion
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D018809:Proliferating Cell Nuclear Antigen; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase; D018844:Cyclin-Dependent Kinases