ABSTRACT

The first photosynthetic organism for which the genomic sequence was completed was the cyanobacterium Synechocystis sp. PCC 6803 (Kaneko et al. 1996). The genome is about 3.6 Mbp, contains over 3,000 genes, and can be searched at the CyanoBase website (http:/ /www.kazusa.or.jp/ cyano/cyano.html). Computer analysis of the genome sequence of Synechocystis sp. PCC 6803 suggests the presence of 3167 potential proteincoding regions, 1416 of which are similar or identical to known genes, 342 have similarity to hypothetical genes from other organisms, and the remaining 1409 genes have no clear homologues (lkeuchi and Tabata 2001). As identification of open reading frames as putative genes sometimes is arbitrary, the precise number of genes remains equivocal.