The WRC domain of GRF transcription factors: Structure and DNA recognition

Abstract

Growth-regulating factors (GRFs) belong to a family of transcription factorsfound in plants which display important roles in growth and development.GRF transcriptional activity is finely tuned by regulatory processes involvingpost-transcriptional repression exerted by microRNA miR396, and protein–protein interactions involving a family of co-transcriptional regulators knownas GRF-interacting factors (GIFs). In this way, the activity of GRF targetgenes is modulated by a highly complex interplay between GRF/GIF iso-form diversity and expression patterns along with miR396 and GIF gradientsthroughout plant tissues. At the protein level, GRFs are composed of twohighly evolutionarily conserved domains known as QLQ and WRC and aless conserved C-terminal trans-activation domain. Whereas QLQ mediatesGRF–GIF interaction by forming a complex with a conserved domain calledSNH (by SYT N-terminal homology) found in GIFs’ N-terminal region, theWRC has been proposed as a putative zinc finger domain responsible fortarget DNA recognition and nuclear import. However, the structural aspectsgoverning GRF transcriptional activity and target recognition remainunknown. In this work, we applied bioinformatic and biophysical analysis tocomprehensively characterize the structural features that modulate the bio-logical function of this protein family with a focus on the WRC domain. Weprovide insights into the structure of the WRC domain in GRFs and explorethe WRC features driving GRFs:DNA complex formation. These findingsoffer new insights into how WRC domains modulate the biological functionsof GRFs, laying the groundwork for future studies on their structure–functionrelationship in gene regulation and development of plants.