Sequential phosphorylation and multisite interactions characterize specific target recognition by the FHA domain of Ki67.
The forkhead-associated (FHA) domain of human Ki67 interacts with the human nucleolar protein hNIFK, recognizing a 44-residue fragment, hNIFK226-269, phosphorylated at Thr234. Here we show that high-affinity binding requires sequential phosphorylation by two kinases, CDK1 and GSK3, yielding pThr238, pThr234 and pSer230. We have determined the solution structure of Ki67FHA in complex with the triply phosphorylated peptide hNIFK226-269(3P), revealing not only local recognition of pThr234 but also the extension of the beta-sheet of the FHA domain by the addition of a beta-strand of hNIFK. The structure of an FHA domain in complex with a biologically relevant binding partner provides insights into ligand specificity and potentially links the cancer marker protein Ki67 to a signaling pathway associated with cell fate specification.
Byeon
In-Ja L
IJ
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, US National Institutes of Health (NIH), Bethesda, Maryland 20892, USA.
Li
Hongyuan
H
Song
Haiyan
H
Gronenborn
Angela M
AM
Tsai
Ming-Daw
MD
D016203:CDC2 Protein Kinase / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003598:Cytoskeletal Proteins; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D019394:Ki-67 Antigen / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000235:genetics*; D013329:Structure-Activity Relationship
D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D019394:Ki-67 Antigen; D046912:Multiprotein Complexes; C492406:NIFK protein, human; C512806:NIN protein, human; D009687:Nuclear Proteins; D016203:CDC2 Protein Kinase; D019204:GTP-Binding Proteins