title: Mechanistic heterogeneity in site recognition by the structurally homologous DNA-binding domains of the ETS family transcription factors Ets-1 and PU.1.
abstract: ETS family transcription factors regulate diverse genes through binding at cognate DNA sites that overlap substantially in sequence. The DNA-binding domains of ETS proteins (ETS domains) are highly conserved structurally yet share limited amino acid homology. To define the mechanistic implications of sequence diversity within the ETS family, we characterized the thermodynamics and kinetics of DNA site recognition by the ETS domains of Ets-1 and PU.1, which represent the extremes in amino acid divergence among ETS proteins. Even though the two ETS domains bind their optimal sites with similar affinities under physiologic conditions, their nature of site recognition differs strikingly in terms of the role of hydration and counter ion release. The data suggest two distinct mechanisms wherein Ets-1 follows a "dry" mechanism that rapidly parses sites through electrostatic interactions and direct protein-DNA contacts, whereas PU.1 utilizes hydration to interrogate sequence-specific sites and form a long-lived complex relative to the Ets-1 counterpart. The kinetic persistence of the high affinity PU.1 · DNA complex may be relevant to an emerging role of PU.1, but not Ets-1, as a pioneer transcription factor in vivo. In addition, PU.1 activity is critical to the development and function of macrophages and lymphocytes, which present osmotically variable environments, and hydration-dependent specificity may represent an important regulatory mechanism in vivo, a hypothesis that finds support in gene expression profiles of primary murine macrophages.
authors: From the Department of Chemistry, Georgia State University, Atlanta, Georgia 30303 and.
authors: Shuo
authors: S
authors: Wang
authors: the Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington 99210-1495.
authors: Miles H
authors: MH
authors: Linde
authors: From the Department of Chemistry, Georgia State University, Atlanta, Georgia 30303 and.
authors: Manoj
authors: M
authors: Munde
authors: the Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington 99210-1495.
authors: Victor D
authors: VD
authors: Carvalho
authors: From the Department of Chemistry, Georgia State University, Atlanta, Georgia 30303 and wdw@gsu.edu.
authors: W David
authors: WD
authors: Wilson
authors: the Department of Pharmaceutical Sciences, Washington State University, Spokane, Washington 99210-1495 gpoon@wsu.edu.
authors: Gregory M K
authors: GM
authors: Poon
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D015374:Biosensing Techniques; D002151:Calorimetry; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D011487:Protein Conformation; D050784:Proto-Oncogene Protein c-ets-1 / Q000737:chemistry / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance; D013816:Thermodynamics; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000737:chemistry; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D004247:DNA; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D014867:Water; D000099232:Proto-Oncogene Protein Spi-1
keywords: ETS Transcription Factor Family; Ets-1; Hydration; Isothermal Titration Calorimetry (ITC); Kinetics; Osmotic Stress; PU.1; Protein-DNA Interaction; Surface Plasmon Resonance (SPR); Thermodynamics