Isolation of Genes Encoding Components of Photosynthetic Apparatus

This chapter describes four methods for the isolation of cyanobacterial genes encoding components of the photosynthetic apparatus. The first and probably most widely applied method involves heterologous hybridization. In higher plants genes encoding components of the photosynthetic apparatus are frequently encoded by the chloroplast DNA. The complete nucleotide sequences of two chloroplast genomes have been determined, and the genes and potential genes which these genomes encode have been extensively analyzed. Molecular biologists studying higher plants have also isolated genes or cDNA clones for many nuclear-encoded proteins which are components of the photosynthetic apparatus. The availability of characterized genes or cDNA clones for higher plant proteins which play a role in photosynthesis provides a ready source of materials for the isolation and subsequent manipulation of cyanobacterial genes. The close homology of the cyanobacterial photosynthetic apparatus to that of higher plants makes many of these genes readily isolatable by heterologous hybridization. The basic mechanics of gene isolation from cyanobacteria are similar, if not identical, to the processes applied to other prokaryotes and eukaryotes.