Transformation of chloroplasts with thepsaB gene encoding a polypeptide of the photosystem I reaction center

A chloroplast photosystem I reaction center mutation.ac-u-g-2.3. ofChlamydomonas reinhardtii has been complemented with a wild typepsaB gene to restore photosynthetic competence. The mutation was mapped in thepsaB coding sequence by chloroplast transformation using subcloned restriction fragments ofpsaB. The mutation was found to be a single base pair deletion resulting in a reading frame shift and premature termination of the polypeptide. Transformants were verified by insertion of a site-directed mutation which created a new restriction enzyme site. These transformations demontrate the feasibility of insertion of site-directed mutations into thepsaB gene in order to elucidate amino acid residues involved in photosystem I assembly and function.