scholarly journals Secondary interaction between MDMX and p53 core domain inhibits p53 DNA binding

2016 ◽  
Vol 113 (19) ◽  
pp. E2558-E2563 ◽  
Author(s):  
Xi Wei ◽  
Shaofang Wu ◽  
Tanjing Song ◽  
Lihong Chen ◽  
Ming Gao ◽  
...  
Keyword(s):  
Dna Binding ◽  
Specific Binding ◽  
Binding Activity ◽  
Proteolytic Fragment ◽  
Core Domain ◽  
Acidic Domain ◽  
Dna Binding Activity ◽  
Ubiquitin E3 Ligase ◽  
Important Regulator ◽  
Release Assay

The MDMX oncoprotein is an important regulator of tumor suppressor p53 activity during embryonic development. Despite sequence homology to the ubiquitin E3 ligase MDM2, MDMX depletion activates p53 without significant increase in p53 level, implicating a degradation-independent mechanism. We present evidence that MDMX inhibits the sequence-specific DNA binding activity of p53. This function requires the cooperation between MDMX and CK1α, and phosphorylation of S289 on MDMX. Depletion of MDMX or CK1α increases p53 DNA binding without stabilization of p53. A proteolytic fragment release assay revealed that in the MDMX–p53 complex, the MDMX acidic domain and RING domain interact stably with the p53 DNA binding domain. These interactions are referred to as secondary interactions because they only occur after the canonical-specific binding between the MDMX and p53 N termini, but exhibit significant binding stability in the mature complex. CK1α cooperates with MDMX to inhibit p53 DNA binding by further stabilizing the MDMX acidic domain and p53 core domain interaction. These results suggest that secondary intermolecular interaction is important in p53 regulation by MDMX, which may represent a common phenomenon in complexes containing multidomain proteins.

scholarly journals Crystallization of and selenomethionine phasing strategy for a SETMAR–DNA complex

2016 ◽  
Vol 72 (9) ◽  
pp. 713-719 ◽  
Author(s):  
Qiujia Chen ◽  
Millie Georgiadis
Keyword(s):  
Dna Binding ◽  
Catalytic Domain ◽  
Specific Binding ◽  
Critical Role ◽  
Binding Activity ◽  
Structural Basis ◽  
Unexpected Finding ◽  
Terminal Inverted Repeat ◽  
Dna Binding Activity ◽  
New Genes

Transposable elements have played a critical role in the creation of new genes in all higher eukaryotes, including humans. Although the chimeric fusion protein SETMAR is no longer active as a transposase, it contains both the DNA-binding domain (DBD) and catalytic domain of theHsmar1transposase. The amino-acid sequence of the DBD has been virtually unchanged in 50 million years and, as a consequence, SETMAR retains its sequence-specific binding to the ancestralHsmar1terminal inverted repeat (TIR) sequence. Thus, the DNA-binding activity of SETMAR is likely to have an important biological function. To determine the structural basis for the recognition of TIR DNA by SETMAR, the design of TIR-containing oligonucleotides and SETMAR DBD variants, crystallization of DBD–DNA complexes, phasing strategies and initial phasing experiments are reported here. An unexpected finding was that oligonucleotides containing two BrdUs in place of thymidines produced better quality crystals in complex with SETMAR than their natural counterparts.

scholarly journals Dependence on androgens of the specific DNA-binding activity of rat ventral-prostate non-histone chromosomal proteins

1981 ◽  
Vol 194 (1) ◽  
pp. 91-98
Author(s):  
B H Lesser ◽  
N L Elliot
Keyword(s):  
Dna Binding ◽  
Binding Proteins ◽  
Specific Binding ◽  
Binding Activity ◽  
Male Rats ◽  
Ventral Prostate ◽  
Trace Quantity ◽  
Chromosomal Proteins ◽  
Dna Binding Activity ◽  
Rat Prostate

Interactions between rat prostate non-histone chromosomal proteins and DNA were studied by using a nitrocellulose-filter-binding technique to monitor the formation of DNA–protein complexes. The total binding activity of the non-histones, as measured by binding of proteins to a trace quantity of labelled DNA, displays no preference for rat DNA relative to Escherichia coli DNA. Sequestration of non-specific binding proteins by preincubation with unlabelled bacterial DNA enables detection of a fraction of rat prostate non-histones that binds preferentially to labelled rat DNA relative to labelled E. coli DNA. After castration of adult male rats, both total and specific binding activities decrease. Administration of 5 alpha-dihydrotestosterone to castrated rats stimulates both total and specific DNA-binding activities of prostate non-histones; specific binding is stimulated to a greater extent than total DNA, indicating that the specific binding proteins constitute a larger fraction of the non-histone proteins in the presence of androgens. The specific DNa-binding activity is dependent on the dose of steroid administered.

scholarly journals Core Promoter Binding by Histone-Like TAF Complexes

2005 ◽  
Vol 25 (1) ◽  
pp. 206-219 ◽  
Author(s):  
Hanshuang Shao ◽  
Merav Revach ◽  
Sandra Moshonov ◽  
Yael Tzuman ◽  
Kfir Gazit ◽  
...  
Keyword(s):  
Dna Binding ◽  
Specific Binding ◽  
Core Promoter ◽  
Binding Activity ◽  
Major Function ◽  
Dna Binding Domains ◽  
Histone Fold ◽  
Binding Domains ◽  
Dna Binding Activity ◽  
Promoter Recognition

ABSTRACT A major function of TFIID is core promoter recognition. TFIID consists of TATA-binding protein (TBP) and 14 TBP-associated factors (TAFs). Most of them contain a histone fold domain (HFD) that lacks the DNA-contacting residues of histones. Whether and how TAF HFDs contribute to core promoter DNA binding are yet unresolved. Here we examined the DNA binding activity of TAF9, TAF6, TAF4b, and TAF12, which are related to histones H3, H4, H2A, and H2B, respectively. Each of these TAFs has intrinsic DNA binding activity adjacent to or within the HFD. The DNA binding domains were mapped to evolutionarily conserved and essential regions. Remarkably, HFD-mediated interaction enhanced the DNA binding activity of each of the TAF6-TAF9 and TAF4b-TAF12 pairs and of a histone-like octamer complex composed of the four TAFs. Furthermore, HFD-mediated interaction stimulated sequence-specific binding by TAF6 and TAF9. These results suggest that TAF HFDs merge with other conserved domains for efficient and specific core promoter binding.

scholarly journals Inhibition of p53 DNA Binding Function by the MDM2 Protein Acidic Domain

2011 ◽  
Vol 286 (18) ◽  
pp. 16018-16029 ◽  
Author(s):  
Brittany Cross ◽  
Lihong Chen ◽  
Qian Cheng ◽  
Baozong Li ◽  
Zhi-Min Yuan ◽  
...  
Keyword(s):  
Dna Binding ◽  
Binding Activity ◽  
Wild Type ◽  
Methyl Transferase ◽  
Reading Frame ◽  
Acidic Domain ◽  
Dna Binding Activity ◽  
Binding Function

MDM2 regulates p53 predominantly by promoting p53 ubiquitination. However, ubiquitination-independent mechanisms of MDM2 have also been implicated. Here we show that MDM2 inhibits p53 DNA binding activity in vitro and in vivo. MDM2 binding promotes p53 to adopt a mutant-like conformation, losing reactivity to antibody Pab1620, while exposing the Pab240 epitope. The acidic domain of MDM2 is required to induce p53 conformational change and inhibit p53 DNA binding. Alternate reading frame binding to the MDM2 acidic domain restores p53 wild type conformation and rescues DNA binding activity. Furthermore, histone methyl transferase SUV39H1 binding to the MDM2 acidic domain also restores p53 wild type conformation and allows p53-MDM2-SUV39H1 complex to bind DNA. These results provide further evidence for an ubiquitination-independent mechanism of p53 regulation by MDM2 and reveal how MDM2-interacting repressors gain access to p53 target promoters and repress transcription. Furthermore, we show that the MDM2 inhibitor Nutlin cooperates with the proteasome inhibitor Bortezomib by stimulating p53 DNA binding and transcriptional activity, providing a rationale for combination therapy using proteasome and MDM2 inhibitors.

scholarly journals MDMX acidic domain inhibits p53 DNA binding in vivo and regulates tumorigenesis

2018 ◽  
Vol 115 (15) ◽  
pp. E3368-E3377 ◽  
Author(s):  
Qingling Huang ◽  
Lihong Chen ◽  
Leixiang Yang ◽  
Xiaoling Xie ◽  
Lin Gan ◽  
...  
Keyword(s):  
Dna Binding ◽  
Target Gene ◽  
Core Domain ◽  
Acidic Domain ◽  
Physiological Relevance ◽  
Important Regulator ◽  
Knockin Mouse

The MDM2 homolog MDMX oncoprotein is indispensable for inhibition of p53 during normal embryonic development and malignant transformation, yet how MDMX harnesses p53 functions is unclear. In addition to a canonical N-terminal p53-binding domain, recent work suggests the central acidic domain of MDMX regulates p53 interaction through intramolecular mimicry and engages in second-site interaction with the p53 core domain in vitro. To test the physiological relevance of these interactions, we generated an MDMX knockin mouse having substitutions in a conserved WW motif necessary for these functions (W201S/W202G). Notably, MDMXSG cells have normal p53 level but increased p53 DNA binding and target gene expression, and rapidly senesce. In vivo, MDMXSG inhibits early-phase disease in Eµ-Myc transgenic mice but accelerates the onset of lethal lymphoma and shortens overall survival. Therefore, MDMX is an important regulator of p53 DNA binding, which complements the role of MDM2 in regulating p53 level. Furthermore, the results suggest that the WW motif has dual functions that regulate p53 and inhibit Myc-driven lymphomas independent of p53.

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