Targeting cytotoxicity and tubulin polymerization by metal–carbene complexes on a purine tautomer platform

2014 ◽  
Vol 43 (26) ◽  
pp. 9838-9842 ◽  
Author(s):  
Shruti Khanna ◽  
Batakrishna Jana ◽  
Abhijit Saha ◽  
Prashant Kurkute ◽  
Surajit Ghosh ◽  
...  
Keyword(s):  
Binding Site ◽  
Structural Investigation ◽  
Tubulin Polymerization ◽  
Carbene Complexes ◽  
Gtp Binding ◽  
Tubulin Binding ◽  
A Site

This communication describes the synthesis, structural investigation and tubulin binding of purine rare imino tautomer based Ag(i) and Hg(ii)–carbene complexes. These complexes exhibit cytotoxicity through tubulin interaction by binding to a site close to the GTP binding site.

scholarly journals Microtubule Regulation in Mitosis: Tubulin Phosphorylation by the Cyclin-dependent Kinase Cdk1

2006 ◽  
Vol 17 (3) ◽  
pp. 1041-1050 ◽  
Author(s):  
Anne Fourest-Lieuvin ◽  
Leticia Peris ◽  
Vincent Gache ◽  
Isabel Garcia-Saez ◽  
Céline Juillan-Binard ◽  
...  
Keyword(s):  
Binding Proteins ◽  
Microtubule Dynamics ◽  
Cyclin Dependent Kinase ◽  
Gtp Binding ◽  
Tubulin Binding ◽  
A Site ◽  
Β Tubulin ◽  
In Cells

The activation of the cyclin-depdndent kinase Cdk1 at the transition from interphase to mitosis induces important changes in microtubule dynamics. Cdk1 phosphorylates a number of microtubule- or tubulin-binding proteins but, hitherto, tubulin itself has not been detected as a Cdk1 substrate. Here we show that Cdk1 phosphorylates β-tubulin both in vitro and in vivo. Phosphorylation occurs on Ser172 of β-tubulin, a site that is well conserved in evolution. Using a phosphopeptide antibody, we find that a fraction of the cell tubulin is phosphorylated during mitosis, and this tubulin phosphorylation is inhibited by the Cdk1 inhibitor roscovitine. In mitotic cells, phosphorylated tubulin is excluded from microtubules, being present in the soluble tubulin fraction. Consistent with this distribution in cells, the incorporation of Cdk1-phosphorylated tubulin into growing microtubules is impaired in vitro. Additionally, EGFP-β3-tubulinS172D/E mutants that mimic phosphorylated tubulin are unable to incorporate into microtubules when expressed in cells. Modeling shows that the presence of a phosphoserine at position 172 may impair both GTP binding to β-tubulin and interactions between tubulin dimers. These data indicate that phosphorylation of tubulin by Cdk1 could be involved in the regulation of microtubule dynamics during mitosis.

Synthesis, Anti-proliferative Evaluation, and Molecular Docking Studies of 3-(alkylthio)-5,6-diaryl-1,2,4-triazines as Tubulin Polymerization Inhibitors

2019 ◽  
Vol 16 (11) ◽  
pp. 1194-1201 ◽  
Author(s):  
Farhad Saravani ◽  
Ebrahim Saeedian Moghadam ◽  
Hafezeh Salehabadi ◽  
Seyednasser Ostad ◽  
Morteza Pirali Hamedani ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Cytotoxic Activity ◽  
Binding Site ◽  
Cell Line ◽  
Cell Lines ◽  
Tubulin Polymerization ◽  
Adenocarcinoma Cell Line ◽  
Adenocarcinoma Cell ◽  
Colchicine Binding Site ◽  
Anti Cancer

Background: The role of microtubules in cell division and signaling, intercellular transport, and mitosis has been well known. Hence, they have been targeted for several anti-cancer drugs. Methods: A series of 3-(alkylthio)-5,6-diphenyl-1,2,4-triazines were prepared and evaluated for their cytotoxic activities in vitro against three human cancer cell lines; human colon carcinoma cells HT-29, human breast adenocarcinoma cell line MCF-7, human Caucasian gastric adenocarcinoma cell line AGS as well as fibroblast cell line NIH-3T3 by MTT assay. Docking simulation was performed to insert these compounds into the crystal structure of tubulin at the colchicine binding site to determine a probable binding model. Compound 5d as the most active compound was selected for studying of microtubule disruption. Results: Compound 5d showed potent cytotoxic activity against all cell lines. The molecular modeling study revealed that some derivatives of triazine strongly bind to colchicine binding site. The tubulin polymerization assay kit showed that the cytotoxic activity of 5d may be related to inhibition of tubulin polymerization. Conclusion: The cytotoxicity and molecular modeling study of the synthesized compounds with their inhibition activity in tubulin polymerization demonstrate the potential of triazine derivatives for development of new anti-cancer agents.

Synthesis and tubulin interaction of thiocolchicines containing an isothiocyanato group. Synthesis of C(2)-deuterated and C(2)-14C-labeled 7-isothiocyanatodeacetamidothiocolchicine

1991 ◽  
Vol 56 (11) ◽  
pp. 2306-2312 ◽  
Author(s):  
Anjum Muzaffar ◽  
Ernest Hamel ◽  
Rouli Bai ◽  
Arnold Brossi
Keyword(s):  
Binding Site ◽  
Covalent Bond ◽  
Tubulin Polymerization ◽  
Low Concentration ◽  
Covalent Interaction ◽  
Isotope Label ◽  
Colchicine Binding Site

Synthesis of isothiocyanato substituted thiocolchicines XI - XIV is described. Introduction of an isotope label is demonstrated with the deuterated isothiocyanate XII and the 14C-labeled analog XIII. These isothiocyanates inhibit tubulin polymerization at low concentration. In addition, the 14C-labeled XIII forms covalent bond(s) with tubulin. Unfortunately, the covalent reaction while rapid, is not inhibited by preincubation of tubulin with colchicine. The covalent interaction of XIII with tubulin thus appears to be nonspecific, limiting its use as a marker of the colchicine binding site on tubulin.

scholarly journals Autoinhibition of the formin Cappuccino in the absence of canonical autoinhibitory domains

2012 ◽  
Vol 23 (19) ◽  
pp. 3801-3813 ◽  
Author(s):  
Batbileg Bor ◽  
Christina L. Vizcarra ◽  
Martin L. Phillips ◽  
Margot E. Quinlan
Keyword(s):  
Circular Dichroism ◽  
Binding Site ◽  
Actin Polymerization ◽  
Intramolecular Interaction ◽  
Hydrodynamic Analysis ◽  
A Site ◽  
Circular Dichroïsm

Formins are a conserved family of proteins known to enhance actin polymerization. Most formins are regulated by an intramolecular interaction. The Drosophila formin, Cappuccino (Capu), was believed to be an exception. Capu does not contain conserved autoinhibitory domains and can be regulated by a second protein, Spire. We report here that Capu is, in fact, autoinhibited. The N-terminal half of Capu (Capu-NT) potently inhibits nucleation and binding to the barbed end of elongating filaments by the C-terminal half of Capu (Capu-CT). Hydrodynamic analysis indicates that Capu-NT is a dimer, similar to the N-termini of other formins. These data, combined with those from circular dichroism, suggest, however, that it is structurally distinct from previously described formin inhibitory domains. Finally, we find that Capu-NT binds to a site within Capu-CT that overlaps with the Spire-binding site, the Capu-tail. We propose models for the interaction between Spire and Capu in light of the fact that Capu can be regulated by autoinhibition.

scholarly journals Structural and functional studies of pyruvate carboxylase regulation by cyclic di-AMP in lactic acid bacteria

2017 ◽  
Vol 114 (35) ◽  
pp. E7226-E7235 ◽  
Author(s):  
Philip H. Choi ◽  
Thu Minh Ngoc Vu ◽  
Huong Thi Pham ◽  
Joshua J. Woodward ◽  
Mark S. Turner ◽  
...  
Keyword(s):  
Binding Site ◽  
Conformational Changes ◽  
Pyruvate Carboxylase ◽  
Adenosine Monophosphate ◽  
Binding Mode ◽  
Functional Studies ◽  
Cellular Processes ◽  
Wide Range ◽  
A Site ◽  
Amp Inhibition

Cyclic di-3′,5′-adenosine monophosphate (c-di-AMP) is a broadly conserved bacterial second messenger that has been implicated in a wide range of cellular processes. Our earlier studies showed that c-di-AMP regulates central metabolism inListeria monocytogenesby inhibiting its pyruvate carboxylase (LmPC), a biotin-dependent enzyme with biotin carboxylase (BC) and carboxyltransferase (CT) activities. We report here structural, biochemical, and functional studies on the inhibition ofLactococcus lactisPC (LlPC) by c-di-AMP. The compound is bound at the dimer interface of the CT domain, at a site equivalent to that in LmPC, although it has a distinct binding mode in the LlPC complex. This binding site is not well conserved among PCs, and only a subset of these bacterial enzymes are sensitive to c-di-AMP. Conformational changes in the CT dimer induced by c-di-AMP binding may be the molecular mechanism for its inhibitory activity. Mutations of residues in the binding site can abolish c-di-AMP inhibition. InL. lactis, LlPC is required for efficient milk acidification through its essential role in aspartate biosynthesis. The aspartate pool inL. lactisis negatively regulated by c-di-AMP, and high aspartate levels can be restored by expression of a c-di-AMP–insensitive LlPC. LlPC has high intrinsic catalytic activity and is not sensitive to acetyl-CoA activation, in contrast to other PC enzymes.

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A1–1.5xEux□0.5xWO4 and A0.64–0.5yEu0.24Liy□0.12–0.5yWO4 (A = Ca, Sr; □ = vacancy)

2015 ◽  
Vol 44 (13) ◽  
pp. 6175-6183 ◽  
Author(s):  
Pengfei Jiang ◽  
Wenliang Gao ◽  
Rihong Cong ◽  
Tao Yang
Keyword(s):  
Solid Solutions ◽  
Structural Characterization ◽  
Structural Investigation ◽  
Vacancy Mechanism ◽  
Charge Balance ◽  
A Site ◽  
Site Vacancy ◽  
Luminescence Behavior

A detailed structural characterization on A1–1.5xEux□0.5xWO4 and A0.64–0.5yEu0.24Liy□0.12–0.5yWO4 (A = Ca, Sr; □ = vacancy) prove the A-site vacancy mechanism for charge balance.

Drosophila transcriptional repressor protein that binds specifically to negative control elements in fat body enhancers

1992 ◽  
Vol 12 (9) ◽  
pp. 4093-4103
Author(s):  
D Falb ◽  
T Maniatis
Keyword(s):  
Binding Site ◽  
Fat Body ◽  
Regulatory Element ◽  
Negative Control ◽  
Nuclear Extracts ◽  
Eukaryotic Proteins ◽  
Adh Gene ◽  
A Site

Expression of the Drosophila melanogaster Adh gene in adults requires a fat body-specific enhancer called the Adh adult enhancer (AAE). We have identified a protein in Drosophila nuclear extracts that binds specifically to a site within the AAE (adult enhancer factor 1 [AEF-1]). In addition, we have shown that AEF-1 binds specifically to two other Drosophila fat body enhancers. Base substitutions in the AEF-1 binding site that disrupt AEF-1 binding in vitro result in a significant increase in the level of Adh expression in vivo. Thus, the AEF-1 binding site is a negative regulatory element within the AAE. A cDNA encoding the AEF-1 protein was isolated and shown to act as a repressor of the AAE in cotransfection studies. The AEF-1 protein contains four zinc fingers and an alanine-rich sequence. The latter motif is found in other eukaryotic proteins known to be transcriptional repressors.

Identification of SAS4 and SAS5, Two Genes That Regulate Silencing in Saccharomyces cerevisiae

Genetics ◽  
1999 ◽  
Vol 153 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Eugenia Y Xu ◽  
Susan Kim ◽  
Kirstin Replogle ◽  
Jasper Rine ◽  
David H Rivier
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acute Myeloid Leukemia ◽  
Binding Site ◽  
Myeloid Leukemia ◽  
Null Alleles ◽  
Human Genes ◽  
Complementation Groups ◽  
A Site ◽  
Acute Myeloid

Abstract In Saccharomyces cerevisiae, chromatin-mediated silencing inactivates transcription of the genes at the HML and HMR cryptic mating-type loci and genes near telomeres. Mutations in the Rap1p and Abf1p binding sites of the HMR-E silencer (HMRa-e**) result in a loss of silencing at HMR. We characterized a collection of 15 mutations that restore the α-mating phenotype to MATα HMRa-e** strains. These mutations defined three complementation groups, two new groups and one group that corresponded to the previously identified SAS2 gene. We cloned the genes that complemented members of the new groups and identified two previously uncharacterized genes, which we named SAS4 and SAS5. Neither SAS4 nor SAS5 was required for viability. Null alleles of SAS4 and SAS5 restored SIR4-dependent silencing at HMR, establishing that each is a regulator of silencing. Null alleles of SAS4 and SAS5 bypassed the role of the Abf1p binding site of the HMR-E silencer but not the role of the ACS or Rap1p binding site. Previous analysis indicated that SAS2 is homologous to a human gene that is a site of recurring translocations involved in acute myeloid leukemia. Similarly, SAS5 is a member of a gene family that included two human genes that are the sites of recurring translocations involved in acute myeloid leukemia.

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