Getting the green light: How chloroplast gene expression is activated by light

In plants, photosynthesis occurs within chloroplasts, organelles that contain a genome encoding photosynthetic complexes. Growth and survival of plants depends on regulated expression of these chloroplast genes in response to developmental and environmental cues. For example, exposure to light causes a dramatic increase in the transcription of photosynthetic genes. This is a defining stage of plant development, but, despite its importance, we do not know how it occurs at the molecular level. In this project, we will investigate how chloroplast transcription is turned on and allow plants to become green. This project will employ a variety of cutting-edge methods to characterise the structures, functions and biological roles of proteins that activate gene expression. Cryogenic electron microscopy (cryo-EM) will be employed to visualise the structure of gene expression complexes. Complementary biochemical and biophysical experiments will be performed to understand the relationship to their biochemical activities. Finally, the essential roles of these proteins in plants will be tested by examining the effect of targeted mutations on chloroplast maturation. These discoveries will support the long-term effort to better control photosynthetic output and timing for improved crops and biotechnologies. They will also shed new light on fundamental biological questions of how genes are read.