▪ Abstract  The nucleotide sequence of the entire genome of the unicellular cyanobacterium, Synechocystis sp. PCC6803, has been determined. The length of the circular genome was 3,573,480 bp, and a total of 3168 protein-coding genes were assigned to the genome by a computer-assisted analysis. The functions of approximately 45% of the genes were deduced based on sequence similarity to known genes. Here are distinctive features of genetic information carried by the cyanobacteria, which have a phylogenetic relationship to both bacteria and plants.