Emergence of an Auxin Sensing Domain in Plant-Associated Bacteria
José A. Gavira, Míriam Rico‐Jiménez, Álvaro Ortega, Natalia V. Petukhova, Dmitrii S. Bug, Albert Castellví, Yuri B. Porozov, Igor B. Zhulin, Tino Krell, Miguel A. Matilla
Abstract
Although antagonists were found to bind different bacterial signal transduction receptors, we are still at the early stages of understanding the molecular details by which these molecules exert their inhibitory effects. Here, we provide insight into the structural changes resulting from the binding of an agonist and an antagonist to a sensor protein. Our data indicate that agonist and antagonist recognition is characterized by small conformational differences in the LBDs that can be efficiently transmitted to the output domain to modulate the final response. LBDs are subject to strong selective pressures and are rapidly evolving domains. An increasing number of reports support the idea that environmental factors drive the evolution of sensor domains. Given the recent evolutionary history of AdmX homologs, as well as their narrow phyletic distribution within plant-associated bacteria, our results are in accordance with a plant-mediated evolutionary process that resulted in the emergence of receptor proteins that specifically sense auxin phytohormones.