2012 Annual Report 1a.Objectives (from AD-416): Solve the crystal structure of the sorghum 4-coumarate CoA ligase and investigate interactions between the enzyme and its bound substrates. 1b.Approach (from AD-416): This will be a joint effort between ARS, who has sorghum 4-coumarate CoA ligases in a protein expression vector, expertise to produce, and assay protein activity, and the Washington State University, who has facilities and expertise to crystallize and solve the crystal structure of the protein. Both partners will collaborate in designing the experiments and interpreting the results. 3.Progress Report: This agreement was established to solve the protein structures of sorghum 4-coumarate CoA ligases using protein crystallography. Purified 4-coumarate CoA ligase proteins and the expression vectors used to produce these proteins were provided to the cooperator. The cooperator is working to produce protein crystals for crystallography. This study will develop a better understanding of fundamental mechanisms controlling cell wall formation and energy availability in sorghum and other bioenergy grasses.