Research Interests
Understanding Auxin Signaling Specificity
The phytohormone auxin is a crucial regulator of all aspects of plant development. The primary transcriptional regulators of auxin signaling, the AUXIN RESPONSE FACTORS (ARF) are members of a large protein family in many plant species. This transcription factor family regulates many developmental processes by modulating the transcription of close to one third of the Arabidopsis thaliana genome. How this large transcription factor family regulates so many distinct processes is not well understood.
In the absence of auxin, the ARF function is inhibited by transcriptional corepressors (Aux/IAAs). In the presence of auxin, these corepressors are poly-ubiquitinated by an F-box protein (TIR1) and degraded via the ubiquitin proteasome pathway. Whereas much is known about the canonical auxin signaling pathway, little is know about other regulators of ARF activity and function.
I seek to understand the factors that regulate ARF function and specificity. Many transcription factors work as homo- and heterodimers, but the relationship between transcription factor dimerization and DNA-binding specificity remains unstudied. The ARF proteins present an appealing model to study transcription factor dimerization. Recent work has described the mechanisms of ARF function, including the molecular basis of ARF DNA binding and ARF dimerization. ARF proteins have a modular structure that includes a C-terminal type I/II Phox and Bem1 (PB1) domain. PB1 domains mediate protein interactions between ARFs in a directional manner, but how the PB1 domain contributes to ARF DNA-binding and dimerization specificity is currently unknown. I am using comparative sequence approaches, biophysical approaches, and genetic approaches to interrogate ARF dimerization affinities and their effect on DNA binding across the genome.