Defining a two-pronged structural model for PB1 (Phox/Bem1p) domain interaction in plant auxin responses

David A. Korasick, Srirupa Chatterjee, Marco Tonelli, Hesam Dashti, Soon Goo Lee, Corey S. Westfall, D. Bruce Fulton, Amy H. Andreotti, Gaya K. Amarasinghe, Lucia C. Strader, Joseph M. Jez

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Phox/Bem1p (PB1) domains are universal structural modules that use surfaces of different charge for protein-protein association. In plants, PB1-mediated interactions of auxin response factors (ARF) and auxin/indole 3-acetic acid inducible proteins regulate transcriptional events modulated by the phytohormone auxin. Here we investigate the thermodynamic and structural basis for Arabidopsis thaliana ARF7 PB1 domain selfinteraction. Isothermal titration calorimetry and NMR experiments indicate that key residues on both the basic and acidic faces of the PB1 domain contribute to and organize coordinately to stabilize protein-protein interactions. Calorimetric analysis of ARF7PB1 site-directed mutants defines a twopronged electrostatic interaction. The canonical PB1 interaction between a lysine and a cluster of acidic residues provides one prong with an arginine and a second cluster of acidic residues defining the other prong. Evolutionary conservation of this core recognition feature and other co-varying interface sequences allows for versatile PB1-mediated interactions in auxin signaling.

Original languageEnglish
Pages (from-to)12868-12878
Number of pages11
JournalJournal of Biological Chemistry
Issue number20
StatePublished - May 15 2015


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