PDBsum entry 3fvh

Cell cycle, peptide binding protein

PDB id

3fvh

Contents

			Protein chain

					233 a.a.

			Ligands

					ACE-LEU-HIS-SER- TPO-ALA-NH2

			Waters ×262

References listed in PDB file

Key reference

Title

Structural and functional analyses of minimal phosphopeptides targeting the polo-Box domain of polo-Like kinase 1.

Authors

S.M.Yun, T.Moulaei, D.Lim, J.K.Bang, J.E.Park, S.R.Shenoy, F.Liu, Y.H.Kang, C.Liao, N.K.Soung, S.Lee, D.Y.Yoon, Y.Lim, D.H.Lee, A.Otaka, E.Appella, J.B.Mcmahon, M.C.Nicklaus, T.R.Burke, M.B.Yaffe, A.Wlodawer, K.S.Lee.

Ref.

Nat Struct Biol, 2009, 16, 876-882. [DOI no: 10.1038/nsmb.1628]

PubMed id

19597481

Abstract

Polo-like kinase-1 (Plk1) has a pivotal role in cell proliferation and is considered a potential target for anticancer therapy. The noncatalytic polo-box domain (PBD) of Plk1 forms a phosphoepitope binding module for protein-protein interaction. Here, we report the identification of minimal phosphopeptides that specifically interact with the PBD of human PLK1, but not those of the closely related PLK2 and PLK3. Comparative binding studies and analyses of crystal structures of the PLK1 PBD in complex with the minimal phosphopeptides revealed that the C-terminal SpT dipeptide functions as a high-affinity anchor, whereas the N-terminal residues are crucial for providing specificity and affinity to the interaction. Inhibition of the PLK1 PBD by phosphothreonine mimetic peptides was sufficient to induce mitotic arrest and apoptotic cell death. The mode of interaction between the minimal peptide and PBD may provide a template for designing therapeutic agents that target PLK1.



	Figure 1. (a–c) Various lengths of N-terminal Cys-(CH[2])[6]–fused Thr78 peptides were cross-linked to beads (a) and then tested for their ability to precipitate PLK1 from mitotic HeLa lysates. The phosphorylated Thr78 residue ('T' in red) and the invariable Ser77 residue ('S' in blue) crucial for PBD binding are indicated in a (above right). Immunoblots with antibody to PLK1 show levels of PLK1 coprecipitated with the indicated peptides. A shortened form of the synthetic peptide optimized for PLK1 PBD binding (MQSpTPL)^13 was included for comparison. Numbers indicate efficiency of PLK1 precipitation by each peptide relative to the PLK1 signal in the input. (d) A 6-mer Thr78 peptide (LHSpTAI) analogous to the synthetic optimal peptide (MQSpTPL) was tested for PLK1 binding as in a–c.		Figure 3. (a) Superposition of phosphopeptide binding pockets of PBD^PL, PBD^PP, PBD^S+G and PBD^S. Gray, PBD; green, PLHSpT; yellow, PLHSpT-associated glycerol molecule; cyan, PPHSpT; magenta, glycerol molecule (two half-occupancy conformations at Ser–1 position) of PBD^S+G; black, two sulfate anions of PBD^S+G and PBD^S (red, oxygen atoms). Differences in exact positions of sulfate and phosphate groups could result from the fact that sulfate is a free anion, whereas phosphate is covalently linked to the phosphopeptide. (b) PBD residues involved in binding of PLHSpT are labeled and shown in cyan. All water molecules that form an interface between the phosphopeptide and PBD are drawn in red mesh. (c) Superposition of PLHSpT (green), PPHSpT (cyan), MQSpTPL (magenta) and PMQSpTPL (gray). (d,e) Mixture of HeLa lysates expressing kinase-inactive Flag-PLK1(K82M), Flag-PLK2(K108M) or Flag-PLK3(K52R) was subjected to pull-down assays as in Figure 2a, with the indicated 5-mer wild-type (PLHSpT) and mutants cross-linked to beads. The nonphosphorylated Thr78 peptide PLHST was used as a control. Numbers above the blot indicate relative efficiency of PLK2 precipitation; numbers below denote relative efficiency of PLK1 precipitation. (f) Nature of interactions between SpT-containing peptides and PLK1 PBD. Alignment of minimal p-T78 peptides (PLHST and LHSTA) and synthetic optimal peptides (PMQSTPL and MQSTPL) are shown. See text for details.

PROCHECK

	Headers