Recognition of an intra-chain tandem 14-3-3 binding site within PKCepsilon.
The phosphoserine/threonine binding protein 14-3-3 stimulates the catalytic activity of protein kinase C-epsilon (PKCepsilon) by engaging two tandem phosphoserine-containing motifs located between the PKCepsilon regulatory and catalytic domains (V3 region). Interaction between 14-3-3 and this region of PKCepsilon is essential for the completion of cytokinesis. Here, we report the crystal structure of 14-3-3zeta bound to a synthetic diphosphorylated PKCepsilon V3 region revealing how a consensus 14-3-3 site and a divergent 14-3-3 site cooperate to bind to 14-3-3 and so activate PKCepsilon. Thermodynamic data show a markedly enhanced binding affinity for two-site phosphopeptides over single-site 14-3-3 binding motifs and identifies Ser 368 as a gatekeeper phosphorylation site in this physiologically relevant 14-3-3 ligand. This dual-site intra-chain recognition has implications for other 14-3-3 targets, which seem to have only a single 14-3-3 motif, as other lower affinity and cryptic 14-3-3 gatekeeper sites might exist.
Kostelecky
Brenda
B
Structural Biology Laboratory, London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
Saurin
Adrian T
AT
Purkiss
Andrew
A
Parker
Peter J
PJ
McDonald
Neil Q
NQ
D048948:14-3-3 Proteins / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding; D051744:Protein Kinase C-epsilon / Q000737:chemistry* / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D013816:Thermodynamics
D048948:14-3-3 Proteins; D010768:Phosphoserine; D051744:Protein Kinase C-epsilon