6hkx
Eg5-inhibitor complexEg5-inhibitor complex
Structural highlights
Disease[KIF11_HUMAN] Defects in KIF11 are the cause of microcephaly with or without chorioretinopathy, lymphedema, or mental retardation (MCLMR) [MIM:152950]. An autosomal dominant disorder that involves an overlapping but variable spectrum of central nervous system and ocular developmental anomalies. Microcephaly ranges from mild to severe and is often associated with mild to moderate developmental delay and a characteristic facial phenotype with upslanting palpebral fissures, broad nose with rounded tip, long philtrum with thin upper lip, prominent chin, and prominent ears. Chorioretinopathy is the most common eye abnormality, but retinal folds, microphthalmia, and myopic and hypermetropic astigmatism have also been reported, and some individuals have no overt ocular phenotype. Congenital lymphedema, when present, is typically confined to the dorsa of the feet, and lymphoscintigraphy reveals the absence of radioactive isotope uptake from the webspaces between the toes.[1] Function[KIF11_HUMAN] Motor protein required for establishing a bipolar spindle. Blocking of KIF11 prevents centrosome migration and arrest cells in mitosis with monoastral microtubule arrays.[2] Publication Abstract from PubMedArry-520 is an advanced drug candidate from the Eg5 inhibitor class undergoing clinical evaluation in patients with relapsed or refractory multiple myeloma. Here we show by structural analysis that Arry-520 binds stoichiometrically to the motor domain of Eg5 in the conventional allosteric loop L5 pocket in a complex that suggests the same structural mechanism as other Eg5 inhibitors. We have previously shown that acquired resistance through mutations in the allosteric binding site located at loop L5 in the Eg5 structure appears to be independent of the inhibitors' scaffold, which suggests that Arry-520 will ultimately have the same fate. When Arry-520 was assessed in two cell lines selected for the expression of either Eg5(D130A) or Eg5(L214A) STLC-resistant alleles, mutations previously shown to convey resistance to this class of inhibitors, it was inactive in both. Surprisingly, when the cells were challenged with ispinesib, another Eg5 inhibitor, the Eg5(D130A) cells were resistant, but those expressing Eg5(L214A) were strikingly sensitive. Molecular dynamics simulations suggest that subtle differences in ligand binding and flexibility in both compound and protein may alter allosteric transmission from the loop L5 site that do not necessarily result in reduced inhibitory activity in mutated Eg5 structures. Whilst we predict that cells challenged with Arry-520 in the clinical setting are likely to acquire resistance through point mutations in the Eg5 binding site, the data for ispinesib suggests that this resistance mechanism is not scaffold independent as previously thought, and new inhibitors can be designed that retain inhibitory activity in these resistant cells. Is the fate of clinical candidate Arry-520 already sealed? Predicting resistance in Eg5-inhibitor complexes.,Indorato RL, Talapatra SK, Lin F, Haider S, Mackay SP, Kozielski F, Skoufias DA Mol Cancer Ther. 2019 Sep 5. pii: 1535-7163.MCT-19-0154. doi:, 10.1158/1535-7163.MCT-19-0154. PMID:31488701[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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