Analysis of the Function of NPH3 and the Role of CUL3-based Ubiquitylation in Phototropic Signaling

University Of Missouri-Columbia, Columbia MO

Investigators

Abstract

Emmanuel Liscum IOS-0817737 Analysis of the function of NPH3 and the role of CUL3-based ubiquitylation in phototropic signaling Plants, unlike animals, are unable to run away from adversity (e.g., herbivores and drought) or toward their next meal (e.g., sunlight and water). Instead plants have evolved strategies that involve organ bending in order to respond to changes in their environment. Dramatic, rapid, and reversible changes in morphology can result from differential growth - unequal cellular elongation in one position of an organ relative to an opposing position. One such response is phototropism, or organ bending in response to directional blue light (BL). Based on preliminary results and recent paradigms developed in fungal and animal systems the investigators hypothesize that NPH3, a protein required for normal phototropism that interacts with the primary phototropic receptor phototropin 1 (phot1), functions as a core component of a CULLIN3-based E3 ubiquitin ligase. They further hypothesize that ubiquitination of phot1 by this complex leads to relocalization of the receptor from the plasma membrane to endomembranes in response to BL, and that this is necessary for the furthered progression of phototropic signals. This project is aimed at addressing this hypothesis by: 1) characterizing phot1 ubiquitylation in response to BL, as well as the role of NPH3 and a CUL3-based E3-ubiquitin ligase in this response; and 2) characterize the influence of ubiquitylation on phot1 localization and phototropic function. Results from these studies will not only provide important insights into the mechanisms by which phototropic signaling occurs, but will also contribute to the blossoming field of CULLIN3-based E3 ligase study, which to this point has been largely dominated by fungal and animal models. This project will provide theoretical and practical training for one technician (female), at least one PhD student (female), one undergraduate student, and two high school students. Genetic resources from the project will be utilized in the PREP (Partnership for Research and Education in Plants) program that the PI participates in to provide hands-on research experience to high school students in Columbia and Jefferson City, MO. Insights into the regulation of plant growth and cellular signaling resulting from these studies, which will published in publicly-accessible and high-profile scientific journals, will hopefully be integrated into current crop improvement programs aimed at increasing economic and ecological aspects of US agriculture.