scholarly journals Mechanisms of in vivo binding site selection of the hematopoietic master transcription factor PU.1

2013 ◽  
Vol 41 (13) ◽  
pp. 6391-6402 ◽  
Author(s):  
Thu-Hang Pham ◽  
Julia Minderjahn ◽  
Christian Schmidl ◽  
Helen Hoffmeister ◽  
Sandra Schmidhofer ◽  
...  
1986 ◽  
Vol 6 (12) ◽  
pp. 4723-4733
Author(s):  
L A Chodosh ◽  
R W Carthew ◽  
P A Sharp

A simple approach has been developed for the unambiguous identification and purification of sequence-specific DNA-binding proteins solely on the basis of their ability to bind selectively to their target sequences. Four independent methods were used to identify the promoter-specific RNA polymerase II transcription factor MLTF as a 46-kilodalton (kDa) polypeptide. First, a 46-kDa protein was specifically cross-linked by UV irradiation to a body-labeled DNA fragment containing the MLTF binding site. Second, MLTF sedimented through glycerol gradients at a rate corresponding to a protein of native molecular weight 45,000 to 50,000. Third, a 46-kDa protein was specifically retained on a biotin-streptavidin matrix only when the DNA fragment coupled to the matrix contained the MLTF binding site. Finally, proteins from the most highly purified fraction which were eluted and renatured from the 44- to 48-kDa region of a sodium dodecyl sulfate-polyacrylamide gel exhibited both binding and transcription-stimulatory activities. The DNA-binding activity was purified 100,000-fold by chromatography through three conventional columns plus a DNA affinity column. Purified MLTF was characterized with respect to the kinetic and thermodynamic properties of DNA binding. These parameters indicate a high degree of occupancy of MLTF binding sites in vivo.


2000 ◽  
Vol 20 (1) ◽  
pp. 389-401 ◽  
Author(s):  
Elisabetta Soldaini ◽  
Susan John ◽  
Stefano Moro ◽  
Julie Bollenbacher ◽  
Ulrike Schindler ◽  
...  

ABSTRACT We have defined the optimal binding sites for Stat5a and Stat5b homodimers and found that they share similar core TTC(T/C)N(G/A)GAA interferon gamma-activated sequence (GAS) motifs. Stat5a tetramers can bind to tandemly linked GAS motifs, but the binding site selection revealed that tetrameric binding also can be seen with a wide range of nonconsensus motifs, which in many cases did not allow Stat5a binding as a dimer. This indicates a greater degree of flexibility in the DNA sequences that allow binding of Stat5a tetramers than dimers. Indeed, in an oligonucleotide that could bind both dimers and tetramers, it was possible to design mutants that affected dimer binding without affecting tetramer binding. A spacing of 6 bp between the GAS sites was most frequently selected, demonstrating that this distance is favorable for Stat5a tetramer binding. These data provide insights into tetramer formation by Stat5a and indicate that the repertoire of potential binding sites for this transcription factor is broader than expected.


2003 ◽  
Vol 185 (20) ◽  
pp. 5993-6004 ◽  
Author(s):  
Anne M. L. Barnard ◽  
Jeffrey Green ◽  
Stephen J. W. Busby

ABSTRACT FNR is an Escherichia coli transcription factor that regulates the transcription of many genes in response to anaerobiosis. We have constructed a series of artificial FNR-dependent promoters, based on the melR promoter, in which a consensus FNR binding site was centered at position −41.5 relative to the transcription start site. A second consensus FNR binding site was introduced at different upstream locations, and promoter activity was assayed in vivo. FNR can activate transcription from these promoters when the upstream FNR binding site is located at many different positions. However, sharp repression is observed when the upstream-bound FNR is located near positions −85 or −95. This repression is relieved by the FNR G74C substitution mutant, previously identified as being defective in transcription repression at the yfiD promoter. A parallel series of artificial FNR-dependent promoters, carrying a consensus FNR binding site at position −61.5 and a second upstream DNA site for FNR, was also constructed. Again, promoter activity was repressed by FNR when the upstream-bound FNR was located at particular positions.


Development ◽  
1992 ◽  
Vol 116 (4) ◽  
pp. 1163-1174 ◽  
Author(s):  
A.P. Gould ◽  
R.A. White

The homeotic genes of Drosophila encode transcription factors that specify morphological differences between segments. To identify the genes that they control, we developed a chromatin immunopurification approach designed to isolate in vivo binding sites for the products of the homeotic gene Ultrabithorax. Here, we report the analysis of one immunopurified binding site. This 110 bp fragment maps within a regulatory region of a gene under homeotic control, connectin. A 4 kb DNA fragment, including the immunopurified binding site, is sufficient to reproduce the appropriate homeotic control within a subset of the full tissue distribution of connectin. Analysis of the role of the 110 bp binding site indicates that it mediates transcriptional controls by Ultrabithorax and other homeotic genes. This is the first report of a functional in vivo binding site isolated using the chromatin immunopurification method. We also show that the protein product of the connectin gene is predicted to be a cell-surface molecule containing leucine-rich repeats. The protein, connectin, can mediate cell-cell adhesion thus suggesting a direct link between homeotic gene function and processes of cell-cell recognition.


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