The crystal structure of the complex of Zea mays alpha subunit with a fragment of human beta subunit provides the clue to the architecture of protein kinase CK2 holoenzyme.
The crystal structure of a complex between the catalytic alpha subunit of Zea mays CK2 and a 23-mer peptide corresponding the C-terminal sequence 181-203 of the human CK2 regulatory beta subunit has been determined at 3.16-A resolution. The complex, composed of two alpha chains and two peptides, presents a molecular twofold axis, with each peptide interacting with both alpha chains. In the derived model of the holoenzyme, the regulatory subunits are positioned on the opposite side with respect to the opening of the catalytic sites, that remain accessible to substrates and cosubstrates. The beta subunit can influence the catalytic activity both directly and by promoting the formation of the alpha2 dimer, in which each alpha chain interacts with the active site of the other. Furthermore, the two active sites are so close in space that they can simultaneously bind and phosphorylate two phosphoacceptor residues of the same substrate.
Department of Organic Chemistry and CNR Biopolymer Research Center, University of Padova, Italy.
R
R
Battistutta
S
S
Sarno
E
E
De Moliner
O
O
Marin
O G
OG
Issinger
G
G
Zanotti
L A
LA
Pinna
D000595:Amino Acid Sequence; D001665:Binding Sites; D047390:Casein Kinase II; D003001:Cloning, Molecular; D003196:Computer Graphics; D018360:Crystallography, X-Ray / Q000379:methods; D006801:Humans; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D003313:Zea mays / Q000201:enzymology
D046911:Macromolecular Substances; D010446:Peptide Fragments; D011994:Recombinant Proteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases