Abstract
Cyanobacteria are a diverse group of prokaryotes known also as blue-green algae. They are known to inhabit a variety of habitats, and show many responses to changes in milieu exterior. Recently, many cyanobacterial genome projects are ongoing, and we can use many genome sequences for informatics analysis. Thus, we performed the phylogenetic profiling analysis using the Pfam, which is a database of protein domains. We performed hmmpfam program for 14 cyanobacterial genomes and obtained about 2000 Pfam domains, then we used hierarchical clustering and selected the result on the viewpoints of biological characters and their habitats. We focus on signal transduction-related domains (GAF, PAS, HisKA and Response_reg, etc.). Interestingly, an approximately three-fold increase in the number of these domains were observed in freshwater cyanobacteria compared to seawater species. In addition, we predict that some domains of unknown function are relevant to nitrogen fixation and heterocyst formation.
