scholarly journals Novel DNA Bis-intercalation by MLN944, a Potent Clinical Bisphenazine Anticancer Drug

2004 ◽  
Vol 279 (44) ◽  
pp. 46096-46103 ◽  
Author(s):  
Jixun Dai ◽  
Chandanamalie Punchihewa ◽  
Prakash Mistry ◽  
Aik Teong Ooi ◽  
Danzhou Yang
Keyword(s):  
Dna Binding ◽  
Anticancer Drug ◽  
Topoisomerase I ◽  
Specific Binding ◽  
Binding Mode ◽  
Dependent Manner ◽  
Sequence Specificity ◽  
Phase I Clinical Trials ◽  
Mobility Shift ◽  
Dna Sequence Specificity

The new bisphenazine anticancer drug MLN944 is a novel cytotoxic agent with exceptional anti-tumor activity against a range of human and murine tumor models both invitroand invivo. MLN944 has recently entered Phase I clinical trials. Despite the structural similarity with its parent monophenazine carboxamide and acridine carboxamide anticancer compounds, MLN944 appears to work by a distinct mechanism of inhibiting DNA transcription rather than the expected mechanism of topoisomerase I and II inhibition. Here we present the first NMR structure of MLN944 complexed with d(ATGCAT)2DNA duplex, demonstrating a novel binding mode in which the two phenazine rings bis-intercalate at the 5′-TpG site, with the carboxamide amino linker lying in the major groove of DNA. The MLN944 molecule adopts a significantly unexpected conformation and side chain orientation in the DNA complex, with the N10 on the phenazine ring protonated at pH 7. The phenazine chromophore of MLN944 is very well stacked with the flanking DNA base pairs using the parallel base-stacking intercalation binding mode. The DNA sequence specificity and the groove recognition of MLN944 binding is determined by several site-specific hydrogen bond interactions with the central G:C base pair as well as the favorable stacking interactions with the 5′-flanking thymine. The specific binding site of MLN944 is known to be recognized by a number of important transcription factors. Our electrophoretic gel mobility shift assay results demonstrated that the c-Jun DNA binding to the AP-1 site is significantly inhibited by MLN944 in a dose-dependent manner. Thus, the exceptional biological activity of MLN944 may be due to its novel DNA binding mode leading to a unique mechanism of action.

scholarly journals Multicomponent differentiation-regulated transcription factors in F9 embryonal carcinoma stem cells.

1991 ◽  
Vol 11 (3) ◽  
pp. 1686-1695 ◽  
Author(s):  
M K Shivji ◽  
N B La Thangue
Keyword(s):  
Stem Cells ◽  
Transcription Factors ◽  
Dna Binding ◽  
Embryonal Carcinoma ◽  
Regulatory Sequence ◽  
Dependent Manner ◽  
Sequence Specificity ◽  
Dna Sequence Specificity ◽  
Cell Extracts

Murine F9 embryonal carcinoma (F9 EC) stem cells have an E1a-like transcription activity that is down-regulated as these cells differentiate to parietal endoderm. For the adenovirus E2A promoter, this activity requires at least two sequence-specific transcription factors, one that binds the cyclic AMP-responsive element (CRE) and the other, DRTF1, the DNA-binding activity of which is down-regulated as F9 EC cells differentiate. Here we report the characterization of several binding activities in F9 EC cell extracts, referred to as DRTF 1a, 1b and 1c, that recognize the DRTF1 cis-regulatory sequence (-70 to -50 region). These activities can be chromatographically separated but are not distinguishable by DNA sequence specificity. Activity 1a is a detergent-sensitive complex in which DNA binding is regulated by phosphorylation. In contrast, activities 1b and 1c are unaffected by these treatments but exist as multicomponent protein complexes even before DNA binding. Two sets of DNA-binding polypeptides, p50DR and p30DR, affinity purified from F9 EC cell extracts produce complexes 1b and 1c. Both polypeptides appear to be present in the same DNA-bound protein complex and both directly contact DNA. These affinity-purified polypeptides activate transcription in vitro in a binding-site-dependent manner. These data indicate the in F9 EC stem cells, multicomponent differentiation-regulated transcription factors contribute to the cellular E1a-like activity.

scholarly journals Multicomponent differentiation-regulated transcription factors in F9 embryonal carcinoma stem cells

1991 ◽  
Vol 11 (3) ◽  
pp. 1686-1695
Author(s):  
M K Shivji ◽  
N B La Thangue
Keyword(s):  
Stem Cells ◽  
Transcription Factors ◽  
Dna Binding ◽  
Embryonal Carcinoma ◽  
Regulatory Sequence ◽  
Dependent Manner ◽  
Sequence Specificity ◽  
Dna Sequence Specificity ◽  
Cell Extracts

Murine F9 embryonal carcinoma (F9 EC) stem cells have an E1a-like transcription activity that is down-regulated as these cells differentiate to parietal endoderm. For the adenovirus E2A promoter, this activity requires at least two sequence-specific transcription factors, one that binds the cyclic AMP-responsive element (CRE) and the other, DRTF1, the DNA-binding activity of which is down-regulated as F9 EC cells differentiate. Here we report the characterization of several binding activities in F9 EC cell extracts, referred to as DRTF 1a, 1b and 1c, that recognize the DRTF1 cis-regulatory sequence (-70 to -50 region). These activities can be chromatographically separated but are not distinguishable by DNA sequence specificity. Activity 1a is a detergent-sensitive complex in which DNA binding is regulated by phosphorylation. In contrast, activities 1b and 1c are unaffected by these treatments but exist as multicomponent protein complexes even before DNA binding. Two sets of DNA-binding polypeptides, p50DR and p30DR, affinity purified from F9 EC cell extracts produce complexes 1b and 1c. Both polypeptides appear to be present in the same DNA-bound protein complex and both directly contact DNA. These affinity-purified polypeptides activate transcription in vitro in a binding-site-dependent manner. These data indicate the in F9 EC stem cells, multicomponent differentiation-regulated transcription factors contribute to the cellular E1a-like activity.

Binding mode and affinity studies of DNA-binding agents using topoisomerase I DNA unwinding assay

2007 ◽  
Vol 17 (4) ◽  
pp. 1013-1017 ◽  
Author(s):  
Ruel E. McKnight ◽  
Aaron B. Gleason ◽  
James A. Keyes ◽  
Sadia Sahabi
Keyword(s):  
Dna Binding ◽  
Topoisomerase I ◽  
Binding Mode ◽  
Dna Unwinding ◽  
Binding Agents ◽  
Dna Binding Agents

scholarly journals A plant DNA-binding protein that recognizes 5-methylcytosine residues.

1989 ◽  
Vol 9 (3) ◽  
pp. 1351-1356 ◽  
Author(s):  
D L Zhang ◽  
K C Ehrlich ◽  
P C Supakar ◽  
M Ehrlich
Keyword(s):  
Dna Binding ◽  
Dna Sequence ◽  
Base Pair ◽  
Binding Protein ◽  
Dna Binding Protein ◽  
Sequence Specificity ◽  
Dna Sequence Specificity ◽  
Plant Dna ◽  
Related Family ◽  
Nuclear Extracts

A novel, 5-methylcytosine-specific, DNA-binding protein, DBP-m, has been identified in nuclear extracts of peas. DBP-m specifically recognizes 5-methylcytosine residues in DNA without appreciable DNA sequence specificity, unlike a mammalian DNA-binding protein (MDBP), which recognizes 5-methylcytosine residues but only in a related family of 14-base-pair sequences.

scholarly journals The retinoblastoma gene product RB stimulates Sp1-mediated transcription by liberating Sp1 from a negative regulator.

1994 ◽  
Vol 14 (7) ◽  
pp. 4380-4389 ◽  
Author(s):  
L I Chen ◽  
T Nishinaka ◽  
K Kwan ◽  
I Kitabayashi ◽  
K Yokoyama ◽  
...  
Keyword(s):  
Dna Binding ◽  
Gene Product ◽  
Binding Activity ◽  
Negative Regulator ◽  
Control Element ◽  
Dependent Manner ◽  
Mobility Shift ◽  
Dna Binding Activity ◽  
Cell Extracts ◽  
Mobility Shift Assay

Studies have demonstrated that the retinoblastoma susceptibility gene product, RB, can either positively or negatively regulate expression of several genes through cis-acting elements in a cell-type-dependent manner. The nucleotide sequence of the retinoblastoma control element (RCE) motif, GCCACC or CCACCC, and the Sp1 consensus binding sequence, CCGCCC, can confer equal responsiveness to RB. Here, we report that RB activates transcription of the c-jun gene through the Sp1-binding site within the c-jun promoter. Preincubation of crude nuclear extracts with monoclonal antibodies to RB results in reduction of Sp1 complexes in a mobility shift assay, while addition of recombinant RB in mobility shift assay mixtures with CCL64 cell extracts leads to an enhancement of DNA-binding activity of SP1. These results suggest that RB is directly or indirectly involved in Sp1-DNA binding activity. A mechanism by which RB regulates transactivation is indicated by our detection of a heat-labile and protease-sensitive Sp1 negative regulator(s) (Sp1-I) that specifically inhibits Sp1 binding to a c-jun Sp1 site. This inhibition is reversed by addition of recombinant RB proteins, suggesting that RB stimulates Sp1-mediated transactivation by liberating Sp1 from Sp1-I. Additional evidence for Sp1-I involvement in Sp1-mediated transactivation was demonstrated by cotransfection of RB, GAL4-Sp1, and a GAL4-responsive template into CV-1 cells. Finally, we have identified Sp1-I, a approximately 20-kDa protein(s) that inhibits the Sp1 complexes from binding to DNA and that is also an RB-associated protein. These findings provide evidence for a functional link between two distinct classes of oncoproteins, RB and c-Jun, that are involved in the control of cell growth, and also define a novel mechanism for the regulation of c-jun expression.

Inhibition of transcription factor assembly and structural stability on mitoxantrone binding with DNA

2010 ◽  
Vol 30 (5) ◽  
pp. 331-340 ◽  
Author(s):  
Shahper N. Khan ◽  
Mohd Danishuddin ◽  
Asad U. Khan
Keyword(s):  
Transcription Factor ◽  
Binding Mode ◽  
Cd Spectroscopy ◽  
Sequence Specificity ◽  
Mobility Shift ◽  
Dna Complexes ◽  
Naked Dna ◽  
Plasmid Nicking Assay ◽  
Modelling Studies ◽  
Mobility Shift Assay

MTX (mitoxantrone) is perhaps the most promising drug used in the treatment of various malignancies. Comprehensive literature on the therapeutics has indicated it to be the least toxic in its class, although its mechanism of action is still not well defined. In the present study, we have evaluated the associated binding interactions of MTX with naked DNA. The mechanism of MTX binding with DNA was elucidated by steady-state fluorescence and a static-type quenching mechanism is suggested for this interaction. Thermodynamic parameters from van 't Hoff plots showed that the interaction of these drugs with DNA is an entropically driven phenomenon. The binding mode was expounded by attenuance measurements and competitive binding of a known intercalator. Sequence specificity of these drug–DNA complexes was analysed by FTIR (Fourier-transform infrared) spectroscopy and molecular modelling studies. CD spectroscopy and the plasmid nicking assay showed that the binding of this drug with DNA results in structural and conformational perturbations. EMSA (electrophoretic mobility-shift assay) results showed that these drug–DNA complexes prevent the binding of octamer TF (transcription factor) to DNA. In summary, the study implicates MTX-induced conformational instability and transcription inhibition on DNA binding.

The combination of sequence-specific and nonspecific DNA-binding modes of transcription factor SATB1

2016 ◽  
Vol 473 (19) ◽  
pp. 3321-3339 ◽  
Author(s):  
Kazuhiko Yamasaki ◽  
Tomoko Yamasaki
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Tertiary Structure ◽  
Specific Binding ◽  
Binding Mode ◽  
Matrix Attachment Region ◽  
Titration Calorimetry ◽  
Affinity Constant ◽  
Target Sequence ◽  
Binding Modes

Transcription factor SATB1 (special AT-rich sequence binding protein 1) contains multiple DNA-binding domains (DBDs), i.e. two CUT-domain repeats (CUTr1 and CUTr2 from the N-terminus) and a homeodomain, and binds to the matrix attachment region (MAR) of DNA. Although CUTr1 and the homeodomain, but not CUTr2, are known to contribute to DNA binding, different research groups have not reached a consensus on which DBD is responsible for recognition of the target sequence in MAR, 5′-TAATA-3′. Here, we used isothermal titration calorimetry to demonstrate that CUTr1 has binding specificity to this motif, whereas the homeodomain shows affinity for a variety of DNAs without specificity. In line with nonspecific DNA-binding properties of the homeodomain, a mutation of the invariant Asn at position 51 of the homeodomain (typically in contact with the A base in a sequence-specific binding mode) did not affect the binding affinity significantly. The NMR analyses and computational modeling of the homeodomain, however, revealed the tertiary structure and DNA-binding mode that are typical of homeodomains capable of sequence-specific binding. We believe that the lack of highly conserved basic residues in the helix relevant to the base recognition loosens its fitting into the DNA groove and impairs the specific binding. The two DBDs, when fused in tandem, showed strong binding to DNA containing the 5′-TAATA-3′ motif with an affinity constant >108 M−1 and retained nonspecific binding activity. The combination of the sequence-specific and nonspecific DNA-binding modes of SATB1 should be advantageous in a search for target loci during transcriptional regulation.

scholarly journals Sequence specificity in DNA binding is determined by association rather than dissociation

2021 ◽  
Author(s):  
Emil Marklund ◽  
Guanzhong Mao ◽  
Sebastian Deindl ◽  
Johan Elf
Keyword(s):  
Dna Binding ◽  
Genetic Information ◽  
Specific Binding ◽  
Theoretical Framework ◽  
Simple Equation ◽  
Target Sequence ◽  
Sequence Specificity ◽  
Target Search ◽  
Target Binding ◽  
Site Recognition

AbstractSequence-specific binding of proteins to DNA is essential for accessing genetic information. Here, we derive a simple equation for target-site recognition, which uncovers a previously unrecognized coupling between the macroscopic association and dissociation rates of the searching protein. Importantly, this relationship makes it possible to recover the relevant microscopic rates from experimentally determined macroscopic ones. We directly test the equation by observing the binding and unbinding of individual lac repressor (LacI) molecules during target search. We find that LacI dissociates from different target sequences with essentially identical microscopic dissociation rates. Instead, sequence specificity is determined by the efficiency with which the protein recognizes different targets, effectively reducing its risk of being retained on a non-target sequence. Our theoretical framework also accounts for the coupling between off-target binding and unbinding of the catalytically inactive Cas9 (dCas9), showing that the binding pathway can be obtained from macroscopic data.One Sentence SummaryAssociation and dissociation rates are anti-correlated for reactions that include a nonspecific probing step.

scholarly journals Biochemical characterization of ferric uptake regulator (Fur) from Aliivibrio salmonicida. Mapping the DNA sequence specificity through binding studies and structural modelling

BioMetals ◽  
2020 ◽  
Vol 33 (4-5) ◽  
pp. 169-185
Author(s):  
Kristel Berg ◽  
Hege Lynum Pedersen ◽  
Ingar Leiros
Keyword(s):  
Biochemical Characterization ◽  
Ferric Uptake Regulator ◽  
Sequence Specificity ◽  
Binding Studies ◽  
Mobility Shift ◽  
Dna Oligomers ◽  
Dna Sequence Specificity ◽  
Aliivibrio Salmonicida ◽  
Target Dna ◽  
Mobility Shift Assay

Abstract Iron is an essential nutrient for bacteria, however its propensity to form toxic hydroxyl radicals at high intracellular concentrations, requires its acquisition to be tightly regulated. Ferric uptake regulator (Fur) is a metal-dependent DNA-binding protein that acts as a transcriptional regulator in maintaining iron metabolism in bacteria and is a highly interesting target in the design of new antibacterial drugs. Fur mutants have been shown to exhibit decreased virulence in infection models. The protein interacts specifically with DNA at binding sites designated as ‘Fur boxes’. In the present study, we have investigated the interaction between Fur from the fish pathogen Aliivibrio salmonicida (AsFur) and its target DNA using a combination of biochemical and in silico methods. A series of target DNA oligomers were designed based on analyses of Fur boxes from other species, and affinities assessed using electrophoretic mobility shift assay. Binding strengths were interpreted in the context of homology models of AsFur to gain molecular-level insight into binding specificity.

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