Abstract
Chloroplast genome originates from the genome of ancestral cyanobacterium that has become endosymbiont. Genomic data of many photosynthetic organisms are available, including genomic sequences of eight cyanobacteria, a red algae Cyanidioschyzon melolae, and a flowering plant Arabidopsis thaliana. Homologous proteins encoded in these genomes were clustered to identify genes specific to photosynthetic organisms. As a result, 56 unknown proteins of Arabidopsis were identified. To confirm whether these unknown proteins are related to photosynthesis, we analyzed the localization of these proteins by transient expression of GFP-fusion constructs followed by fluorescence microscopy. The expression of the genes coding for these proteins were also analyzed by RNA-blot analysis using RNA extracted from light- and dark-grown 7-day-old seedlings. Consequently, it was found that 53 GFP-fusion proteins were localized in the plastids, and 38 of the genes showed light-regulated expression. Further analysis of the phenotypes of tag-lines is being in progress.
