Structure and Function of ε-Subunit of ATP Synthase in Higher Plant Chloroplast

The e-subunit is the smallest subunit of chloroplast ATP synthase, and is known to inhibit ATPase activity in isolated CF1-ATPase. As a result e is sometimes called an inhibitory subunit. In addition, and perhaps more importantly, the e -subunit is essential for the coupling of proton translocation to ATP synthesis (as proton gate). The relation between the structure and function of e -subunit of ATP synthase in higher plant chloroplast has been studied by molecular biological methods such as site-directed mu-tagenesis and truncations for C- or N-terminus of e -subunit. The results showed that: (1) Thr42 of e-subunit is important for its structure and function; (2) compared with the e-subunit in E.coli, the e-subunit of chloroplast ATP synthase is more sensitive to C- or N-terminus truncations.