Nucleotide sequence of cDNA clones encoding the complete precursor for subunit delta of thylakoid-located ATP synthase from spinach

Abstract

The nucleotide sequence of the entire nuclear-encoded precursor for subunit delta of the ATP synthase from spinach thylakoid membranes was determined by cDNA sequencing. Appropriate recombinant DNAs were selected from pBR322 and lambda gt11 libraries made from polyadenylated RNA of greening spinach seedlings. The mature protein consists of 187 amino acid residues corresponding to a molecular weight of 20468. The precursor protein (257 amino acid residues; M r=27676) is probably processed between a Met-Val bond. The predicted secondary structure of the transit sequence (70 residues; 7.2 kDa) resembles that of the Rieske Fe/S polypeptide, but shows little similarity with those of stromal or luminal proteins. The comparison of the chloroplast delta amino acid sequence with the published delta sequences from respiratory ATP synthases of bacterial and mitochondrial sources and from the thylakoid ATP synthase of the cyanobacterium Synechococcus suggests substantial divergence at the genic level although structural elements appear to be remarkably conserved.