title: STAT1:DNA sequence-dependent binding modulation by phosphorylation, protein:protein interactions and small-molecule inhibition.
abstract: The DNA-binding specificity and affinity of the dimeric human transcription factor (TF) STAT1, were assessed by total internal reflectance fluorescence protein-binding microarrays (TIRF-PBM) to evaluate the effects of protein phosphorylation, higher-order polymerization and small-molecule inhibition. Active, phosphorylated STAT1 showed binding preferences consistent with prior characterization, whereas unphosphorylated STAT1 showed a weak-binding preference for one-half of the GAS consensus site, consistent with recent models of STAT1 structure and function in response to phosphorylation. This altered-binding preference was further tested by use of the inhibitor LLL3, which we show to disrupt STAT1 binding in a sequence-dependent fashion. To determine if this sequence-dependence is specific to STAT1 and not a general feature of human TF biology, the TF Myc/Max was analysed and tested with the inhibitor Mycro3. Myc/Max inhibition by Mycro3 is sequence independent, suggesting that the sequence-dependent inhibition of STAT1 may be specific to this system and a useful target for future inhibitor design.
authors.affiliation: Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Bonham
authors.forename: Nikola
authors.initials: N
authors.lastname: Wenta
authors.forename: Leah M
authors.initials: LM
authors.lastname: Osslund
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Prussin
authors.forename: Uwe
authors.initials: U
authors.lastname: Vinkemeier
authors.forename: Norbert O
authors.initials: NO
authors.lastname: Reich
mesh_terms: D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D055503:Protein Multimerization; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C106465:MNT protein, human; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D012097:Repressor Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D004247:DNA