4h71

Human Plk1-PBD in complex with Poloxime ((E)-4-(hydroxyimino)-2-isopropyl-5-methylcyclohexa-2,5-dienone)

spinqualitylabelsall models 4h71, resolution 1.93Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4h71 is a 2 chain structure with sequence from Homo sapiens. This structure supersedes the now removed PDB entry 3mhn. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.93Å Ligands: GOL, PXE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Disease PLK1_HUMAN Note=Defects in PLK1 are associated with some cancers, such as gastric, thyroid or B-cell lymphomas. Expression is cancer increased in tumor tissues with a poor prognosis, suggesting a role in malignant transformations and carcinogenesis. Function PLK1_HUMAN Serine/threonine-protein kinase that performs several important functions throughout M phase of the cell cycle, including the regulation of centrosome maturation and spindle assembly, the removal of cohesins from chromosome arms, the inactivation of anaphase-promoting complex/cyclosome (APC/C) inhibitors, and the regulation of mitotic exit and cytokinesis. Polo-like kinase proteins acts by binding and phosphorylating proteins are that already phosphorylated on a specific motif recognized by the POLO box domains. Phosphorylates BORA, BUB1B/BUBR1, CCNB1, CDC25C, CEP55, ECT2, ERCC6L, FBXO5/EMI1, FOXM1, KIF20A/MKLP2, MLF1IP, NEDD1, NINL, NPM1, NUDC, PKMYT1/MYT1, PLK1S1/KIZ, PPP1R12A/MYPT1, PRC1, RACGAP1/CYK4, SGOL1, STAG2/SA2, TEX14, TOPORS, p73/TP73, TPT1 and WEE1. Plays a key role in centrosome functions and the assembly of bipolar spindles by phosphorylating PLK1S1/KIZ, NEDD1 and NINL. NEDD1 phosphorylation promotes subsequent targeting of the gamma-tubulin ring complex (gTuRC) to the centrosome, an important step for spindle formation. Phosphorylation of NINL component of the centrosome leads to NINL dissociation from other centrosomal proteins. Involved in mitosis exit and cytokinesis by phosphorylating CEP55, ECT2, KIF20A/MKLP2, MLF1IP, PRC1 and RACGAP1. Recruited at the central spindle by phosphorylating and docking PRC1 and KIF20A/MKLP2; creates its own docking sites on PRC1 and KIF20A/MKLP2 by mediating phosphorylation of sites subsequently recognized by the POLO box domains. Phosphorylates RACGAP1, thereby creating a docking site for the Rho GTP exchange factor ECT2 that is essential for the cleavage furrow formation. Promotes the central spindle recruitment of ECT2. Plays a central role in G2/M transition of mitotic cell cycle by phosphorylating CCNB1, CDC25C, FOXM1, MLF1IP, PKMYT1/MYT1, PPP1R12A/MYPT1 and WEE1. Part of a regulatory circuit that promotes the activation of CDK1 by phosphorylating the positive regulator CDC25C and inhibiting the negative regulators WEE1 and PKMYT1/MYT1. Also acts by mediating phosphorylation of cyclin-B1 (CCNB1) on centrosomes in prophase. Phosphorylates FOXM1, a key mitotic transcription regulator, leading to enhance FOXM1 transcriptional activity. Involved in kinetochore functions and sister chromatid cohesion by phosphorylating BUB1B/BUBR1, FBXO5/EMI1 and STAG2/SA2. PLK1 is high on non-attached kinetochores suggesting a role of PLK1 in kinetochore attachment or in spindle assembly checkpoint (SAC) regulation. Required for kinetochore localization of BUB1B. Regulates the dissociation of cohesin from chromosomes by phosphorylating cohesin subunits such as STAG2/SA2. Phosphorylates SGOL1: required for spindle pole localization of isoform 3 of SGOL1 and plays a role in regulating its centriole cohesion function. Mediates phosphorylation of FBXO5/EMI1, a negative regulator of the APC/C complex during prophase, leading to FBXO5/EMI1 ubiquitination and degradation by the proteasome. Acts as a negative regulator of p53 family members: phosphorylates TOPORS, leading to inhibit the sumoylation of p53/TP53 and simultaneously enhance the ubiquitination and subsequent degradation of p53/TP53. Phosphorylates the transactivation domain of the transcription factor p73/TP73, leading to inhibit p73/TP73-mediated transcriptional activation and pro-apoptotic functions. Phosphorylates BORA, and thereby promotes the degradation of BORA. Contributes to the regulation of AURKA function. Also required for recovery after DNA damage checkpoint and entry into mitosis. Publication Abstract from PubMed Phosphorylation-dependent protein-protein interaction has rarely been targeted in medicinal chemistry. Thymoquinone, a naturally occurring antitumor agent, disrupts prephosphorylated substrate recognition by the polo-box domain of polo-like kinase 1, a key mitotic regulator responsible for various carcinogenesis when overexpressed. Here, crystallographic studies reveal that the phosphoserine/phosphothreonine recognition site of the polo-box domain is the binding pocket for thymoquinone and its analogue poloxime. Both small molecules displace phosphopeptides bound with the polo-box domain in a slow but noncovalent binding mode. A conserved water bridge and a cation-pi interaction were found as their competition strategy against the phosphate group. This mechanism sheds light on small-molecule intervention of phospho-recognition by the polo-box domain of polo-like kinase 1 and other phospho-binding proteins in general. Thymoquinone Blocks pSer/pThr Recognition by Plk1 Polo-Box Domain As a Phosohate Mimic.,Yin Z, Song Y, Rehse PH ACS Chem Biol. 2013 Feb 15;8(2):303-8. doi: 10.1021/cb3004379. Epub 2012 Nov 12. PMID:23135290 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Serine/threonine protein kinase 3D structures

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