Phylogenetic analysis of SPS, SPP and SuS proteins based on GTD and PHD sequences. Homologs were retrieved from public databases (JGI-DOE, http://www.jgi.doe.gov) by BLASTp searches using as query SPS and SuS of Anabaena sp PCC 7120, and SPS and SPP of Synechocystis sp. PCC 6803. Unrooted dendrograms were obtained using the maximum parsimony (1000 replicates). After sequence alignments, GTD (A) or PHD (B) regions described by Cumino et al. [19] were identified with ClustalW [30]. Trees were generated with the MEGA5 software [31]. Major groups are identified to give clues about their function, species, or taxonomic information: (A) GTDs corresponding to bidomainal and unidomainal SPSs and SuS; (B) PHDs, corresponding to SPP and to bidomainal SPSs. Cyanobacteria, blue lines; plants, green lines; bacteria, grey lines. Bootstrap results are not shown when values were lower than 90%.