title: Structure of the regulatory subunit of CK2 in the presence of a p21WAF1 peptide demonstrates flexibility of the acidic loop.
abstract: A truncated form of the regulatory subunit of the protein kinase CK2beta (residues 1-178) has been crystallized in the presence of a fragment of the cyclin-dependent kinase inhibitor p21WAF1 (residues 46-65) and the structure solved at 2.9 A resolution by molecular replacement. The core of the CK2beta dimer shows a high structural similarity with that identified in previous structural analyses of the dimer and the holoenzyme. However, the electron density corresponding to the substrate-binding acidic loop (residues 55-64) indicates two conformations that differ from that of the holoenzyme structure [Niefind et al. (2001), EMBO J. 20, 5320-5331]. Difference electron density near the dimerization region in each of the eight protomers in the asymmetric unit is attributed to between one and eight amino-acid residues of a complexed fragment of p21WAF1. This binding site corresponds to the solvent-accessible part of the conserved zinc-finger motif.
authors.affiliation: Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, England.
authors.forename: Loic
authors.initials: L
authors.lastname: Bertrand
authors.forename: Muhammed F R
authors.initials: MF
authors.lastname: Sayed
authors.forename: Xue-Yuan
authors.initials: XY
authors.lastname: Pei
authors.forename: Emilio
authors.initials: E
authors.lastname: Parisini
authors.forename: Venugopal
authors.initials: V
authors.lastname: Dhanaraj
authors.forename: Victor M
authors.initials: VM
authors.lastname: Bolanos-Garcia
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Allende
authors.forename: Tom L
authors.initials: TL
authors.lastname: Blundell
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D047390:Casein Kinase II / Q000737:chemistry*; D018797:Cell Cycle Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D050759:Cyclin-Dependent Kinase Inhibitor p21; D019281:Dimerization; D004583:Electrons; D004926:Escherichia coli / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis / Q000378:metabolism; D016335:Zinc Fingers
chemical_list: C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D008024:Ligands; D010455:Peptides; D005982:Glutathione Transferase; D047390:Casein Kinase II