In our laboratory, we are exploring the molecular, structural and cellular functions of several PII-like proteins; For example:
1) PII-like protein SbtB is linking the second messenger cAMP to carbon sensation
To cope with low atmospheric CO2concentrations that developed over the course of evolution, cyanobacteria evolved a CO2-concentrating mechanism (CCM), which elevates CO2levels in the vicinity of RubisCO, the key enzyme of CO2fixation. Recently, we characterized a unique component of cyanobacterial CCM, the PII-like signaling protein SbtB, which provided new insights into carbon sensing in cyanobacteria. We found that SbtB senses a variety of adenosine nucleotides, including the second messenger cAMP. Moreover, physiological and biochemical studies indicated importance of SbtB for acclimation to varying carbon regimes in the ecological niches of cyanobacteria. Therefore, PII-like protein SbtB represents a new principle of carbon sensing via second messengercAMP binding, to regulate the cyanobacterial carbon concentrating mechanisms. However, the whole regulatory network of SbtB remains undiscovered.