Two-Component Signal Transduction Systems in the Cyanobacterium Synechocystis sp. PCC 6803

Two-component systems are signal transduction systems which enable bacteria to regulate cellu- lar functions in response to changing environmental conditions. The unicellular Synechocystis sp. PCC 6803 has become a model organism for a range of biochemical and molecular biology studies aiming at investi- gating environmental stress response. The publication of the complete genome sequence of the cyanobac- terium Synechocystis sp. PCC 6803 provided a tremendous stimulus for research in this field, and at least 80 open reading frames were identified as members of the two-component signal transduction systems in this single species of cyanobacteria. To date, functional roles have been determined for only a limited num- ber of such proteins. This review summarizes our current knowledge about the two-component signal trans- duction systems in Synechocystis sp. PCC 6803 and describes recent achievements in elucidating the func- tional roles of these systems.