Genes and transcripts for the ATP synthase CF₀ subunits I and II from spinach thylakoid membranes

Subunits I and II of the ATP synthase CF₀ in spinach are encoded by plastid and nuclear genes, respectively. Using hybrid selection translation, cell-free transcription-translation of cloned restriction fragments and an appropriate antiserum, a single gene for subunit I has been located on the circular plastid chromosome between the genes for the ATP synthase proteolipid and subunit alpha. This finding implies that the five plastome-coded ATP synthase subunits in spinach are arranged in two clusters which are separated by approximately 40 kilobase pairs of DNA. The genes of each cluster appear to be transcribed into large RNA species. The analysis indicates that the putative polycistronic proteolipid/CF₀-I/alpha transcript is post-transcriptionally modified. The previous assumption that the structural gene for subunit I is split has not been excluded.-The transcript for subunit II has been found in the cytosolic RNA fraction. It lacks complementarity to plastid DNA and appears to be decoded into a protein precursor.-Evidence is presented that spinach chloroplast ATP synthase contains more than eight subunits.