论文部分内容阅读
The conserved residue Gly47 of the chloroplast ATP synthase ε subunit was substituted with Leu, Arg, Ala and Glu by site-directed mutagenesis. This process generated the mutants εG47L, εG47R,εG47A and εG47E, respectively. All the ε variants showed lower inhibitory effects on the soluble CF1(-ε)Ca2+-ATPase compared with wild-type ε. In reduced conditions, εG47E and εG47R had a lower inhibitory effect on the oxidized CF1(-ε) Ca2+-ATPase compared with wild-type ε. In contrast, εG47L and εG47A increased the Ca2+-ATPase activity of soluble oxidized CF1(-ε). The replacement of Gly47 significantly impaired the interaction between the subunit ε and γ in an in vitro binding assay. Further study showed that all ε variants were more effective in blocking proton leakage from the thylakoid membranes. This enhanced ATP synthesis of the chloroplast and restored ATP synthesis activity of the reconstituted membranes to a level that was more efficient than that achieved by wild-type ε. These results indicate that the conserved Gly47 residue of the ε subunit is very important for maintaining the structure and function of the ε subunit and may affect the interaction between the ε subunit, β subunit of CF1 and subunit Ⅲ of CF0, thereby regulating the ATP hydrolysis and synthesis, as well as the proton translocation role of the subunit Ⅲ of CF0.