PH modulates the binding of early growth response protein 1 transcription factor to DNA

David C. Mikles, Vikas Bhat, Brett J. Schuchardt, Brian J. Deegan, Kenneth L. Seldeen, Caleb B. McDonald, Amjad Farooq

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

The transcription factor early growth response protein (EGR)1 orchestrates a plethora of signaling cascades involved in cellular homeostasis, and its downregulation has been implicated in the development of prostate cancer. Herein, using a battery of biophysical tools, we show that the binding of EGR1 to DNA is tightly regulated by solution pH. Importantly, the binding affinity undergoes an enhancement of more than an order of magnitude with an increase in pH from 5 to 8, implying that the deprotonation of an ionizable residue accounts for such behavior. This ionizable residue is identified as His382 by virtue of the fact that its replacement by nonionizable residues abolishes the pH dependence of the binding of EGR1 to DNA. Notably, His382 inserts into the major groove of DNA, and stabilizes the EGR1-DNA interaction via both hydrogen bonding and van der Waals contacts. Remarkably, His382 is mainly conserved across other members of the EGR family, implying that histidine protonation-deprotonation may serve as a molecular switch for modulating the protein-DNA interactions that are central to this family of transcription factors. Collectively, our findings reveal an unexpected but a key step in the molecular recognition of the EGR family of transcription factors, and suggest that they may act as sensors of pH within the intracellular environment. We show that the binding of EGR1 transcription factor to DNA is tightly regulated by solution pH by virtue of the ability of His382 to undergo protonation- deprotonation equilibrium. Remarkably, His382 is predominantly conserved across other members of EGR1 family, implying that histidine protonation-deprotonation may serve as a molecular switch for modulating protein-DNA interactions central to this family of transcription factors.

Original languageEnglish (US)
Pages (from-to)3669-3684
Number of pages16
JournalFEBS Journal
Volume280
Issue number15
DOIs
StatePublished - Aug 2013

Keywords

  • histidine protonation
  • intracellular pH
  • protein dynamics
  • protein-DNA thermodynamics
  • zinc fingers

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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    Mikles, D. C., Bhat, V., Schuchardt, B. J., Deegan, B. J., Seldeen, K. L., McDonald, C. B., & Farooq, A. (2013). PH modulates the binding of early growth response protein 1 transcription factor to DNA. FEBS Journal, 280(15), 3669-3684. https://doi.org/10.1111/febs.12360