9513366 Deng Signals from the environment are perceived by specific regulatory receptors in plants, and transduced and integrated with developmental signals to control growth and development. The long term goal of this research is to dissect the molecular mechanisms by which such signals are transduced and integrated to modulate plant development by using light-regulated seedling development of Arabidopsis thaliana as a model system. Ten pleiotropic COP/DET/FUS loci have been identified, which when mutated fail to suppress the photomorphogenic development in darkness and result in dark-grown seedlings phenocopying the light-grown siblings. One of the ten loci, COP9 locus, has been cloned and found to encode a novel, ubiquitously expressed 23 kDa protein. It was demonstrated that COP9 acts as a subunit in a large (560kDa) multiple subunit complex, which is nuclear localized and whose conformation is probably modulated by light. The results suggest that the COP9 complex defines a step in the nexus of the network mediating light control of seedling development. To further characterize the structure of the complex and its functional role in the network mediating light control of plant development, the next stage of investigation will focus on accomplishing two major goals: 1) cloning of the genes and biochemical characterization of the subunits of the complex and 2) understanding the biochemical and cellular basis of the function of the COP9 complex function and its molecular interaction with other components in the light regulatory network. %%% Accomplishment of the proposed investigation will ascertain the nature of a critical regulatory complex that links light and possibly other signals to seedling development and could provide novel insights into the relationships between regulatory components of the network of elements affecting light control of plant development. ***
