Structure and Biogenesis of Chloroplast Coupling Factor CF₀CF₁-ATPase

Chloroplast coupling factor catalyzes the synthesis of adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate in the thylakoids of higher plants. This enzyme is similar in structure and function to that found in mitochondria and bacteria. This chapter presents a summary of some of the important progress regarding structure and biogenesis of the chloroplast coupling factor that has been made in the past few years and discusses the future direction of this field. The proton-translocating ATPase complex consists of two domains that can be separated and studied independently. The complex is located on the chloroplast thylakoid membrane, concentrated predominantly on the stromal lamellae. The entire complex spans the chloroplast thylakoid membrane and has a large segment of its structure on the surface of the membrane facing the chloroplast stroma. The catalytic portion of the complex, which contains the binding sites for adenine nucleotides and inorganic phosphate, can be isolated in soluble form and retains a unidirectional enzyme activity. Thus, a major part of this complex, known as the CF₁ moiety, can be studied as a soluble enzyme. The membrane-embedded domain, referred to as CF₀, consists of four polypeptide subunits.