title: Serendipitous alkylation of a Plk1 ligand uncovers a new binding channel.
abstract: We obtained unanticipated synthetic byproducts from alkylation of the δ(1) nitrogen (N3) of the histidine imidazole ring of the polo-like kinase-1 (Plk1) polo-box domain (PBD)-binding peptide PLHSpT. For the highest-affinity byproduct, bearing a C(6)H(5)(CH(2))(8)- group, a Plk1 PBD cocrystal structure revealed a new binding channel that had previously been occluded. An N-terminal PEGylated version of this peptide containing a hydrolytically stable phosphothreonyl residue (pT) bound the Plk1 PBD with affinity equal to that of the non-PEGylated parent but showed markedly less interaction with the PBDs of the two closely related proteins Plk2 and Plk3. Treatment of cultured cells with this PEGylated peptide resulted in delocalization of Plk1 from centrosomes and kinetochores and in chromosome misalignment that effectively induced mitotic block and apoptotic cell death. This work provides insights that might advance efforts to develop Plk1 PBD-binding inhibitors as potential Plk1-specific anticancer agents.
authors.affiliation: Chemical Biology Laboratory, Molecular Discovery Program, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, Maryland, USA.
authors.forename: Fa
authors.initials: F
authors.lastname: Liu
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Park
authors.forename: Wen-Jian
authors.initials: WJ
authors.lastname: Qian
authors.forename: Dan
authors.initials: D
authors.lastname: Lim
authors.forename: Martin
authors.initials: M
authors.lastname: Gräber
authors.forename: Thorsten
authors.initials: T
authors.lastname: Berg
authors.forename: Michael B
authors.initials: MB
authors.lastname: Yaffe
authors.forename: Kyung S
authors.initials: KS
authors.lastname: Lee
authors.forename: Terrence R
authors.initials: TR
authors.lastname: Burke
mesh_terms: D000478:Alkylation; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry*; D018385:Centrosome / Q000187:drug effects; D006367:HeLa Cells; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D018386:Kinetochores / Q000187:drug effects; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D010769:Phosphothreonine / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011485:Protein Binding / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D017434:Protein Structure, Tertiary / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000737:chemistry*; D025521:Tumor Suppressor Proteins; D000097869:Polo-Like Kinase 1; D000097868:Polo-like Kinases
chemical_list: D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D006639:Histidine; D010455:Peptides; D010769:Phosphothreonine; D011092:Polyethylene Glycols; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D000097869:Polo-Like Kinase 1; C486256:PLK3 protein, human; D000097868:Polo-like Kinases; C496126:PLK2 protein, human