My proposed research seeks to further characterize the aerobic oxidative cyclase reaction involved in chlorophyll biosynthesis. The cyclase reaction has been known for many years, however its molecular and genetic components remained unknown until recently. CHL27 was identified as being a component of the reaction in Arabidopsis thaliana, and two homologs, CHL27A and CHL27B, exist in Chlamydomonas reinhardtii. My research will first focus on elucidating the mechanisms that control the subcellular localization of CN27A and CN27B. Second, due to CHL27's accumulation in barley etioplasts, I will characterize its possible role in chloroplast development. Third, I will create and characterize a CHL27B knock out mutant through RNA interference techniques. And finally, because reconstituted cyclase reactions require both soluble and membrane components, I will identify and further characterize additional components required for the reaction. [unreadable] [unreadable]