| Abstract: | Subunit interactions among the chloroplast ATP synthase subunits were studied using the yeast two-hybrid system. Various pairwise
combinations of genes encoding α, β, γ, δ and ε subunits ofSpinach ATP synthase fused to the binding domain or activation domain of GAL4 DNA were introduced into yeast and then expression
of a reporter gene encoding β-galactosidase was detected. Of all the combinations, that of γ and ε subunit genes showed the
highest level of reporter gene expression, while those of α and β, a and ε, β and ε and β and δ induced stable and significant
reporter gene expression. The combination of δ and ε as well as that of δ and γ induced weak and unstable reporter gene expression.
However, combinations of α and γ, β and γ and α and δ did not induce reporter gene expression. These results suggested that
specific and strong interactions between γ and ε, α and β, α and ε, β and ε and β and δ subunits, and weak and transient interactions
between δ and ε and δ and γ subunits occurred in the yeast cell in the two-hybrid system. These results give a new look into
the structural change of ATP synthase during catalysis. |
