Two glutamic acid residues in the DNA-binding domain are engaged in the release of STAT1 dimers from DNA

BMC Cell Biology

Research Article

Volker Ruppert¹  Verena Koch¹  Thomas Meyer²  Julia Staab² 

[1] Klinik für Kardiologie, Philipps-Universität Marburg, Marburg, Germany;Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Waldweg 33, 37073, Göttingen, Germany;

关键词: Staurosporine;    Nuclear Accumulation;    Green Fluorescent Protein Fusion;    STAT1 Dimer;    Glutamic Acid Residue;   

DOI  :  10.1186/1471-2121-13-22

 received in 2012-04-26, accepted in 2012-08-21,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundIn interferon-γ-stimulated cells, the dimeric transcription factor STAT1 (s ignal t ransducer and a ctivator of t ranscription 1) recognizes semi-palindromic motifs in the promoter regions of cytokine-driven target genes termed GAS (g amma-a ctivated s ites). However, the molecular steps that facilitate GAS binding and the subsequent liberation of STAT1 homodimers from these promoter elements are not well understood.ResultsUsing a mutational approach, we identified two critical glutamyl residues within the DNA-binding domain adjacent to the phosphodiester backbone of DNA which efficiently release phospho-STAT1 from DNA. The release of STAT1 dimers from DNA enhances transcriptional activity on both interferon-driven reporter and endogenous target genes. A substitution of either of the two glutamic acid residues broadens the repertoire of putative binding sites on DNA and enhances binding affinity to GAS sites. However, despite elevated levels of tyrosine phosphorylation and a prolonged nuclear accumulation period, the STAT1 DNA-binding mutants show a significantly reduced transcriptional activity upon stimulation of cells with interferon-γ. This reduced transcriptional response may be explained by the deposition of oligomerized STAT1 molecules outside GAS sites.ConclusionsThus, two negatively charged amino acid residues in the DNA-binding domain are engaged in the liberation of STAT1 from DNA, resulting in a high dissociation rate from non-GAS sites as a key feature of STAT1 signal transduction, which positively regulates cytokine-dependent gene expression probably by preventing retention at transcriptionally inert sites.

【 授权许可】

Unknown   
© Koch et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.