Abstract
The PAS domain is one of the important signaling modules that monitor changes in light, redox potential, oxygen or small ligands. The PAS domain superfamily is highly diverse in sequence and in length but is conserved in the basic three-dimensional structure. Recently, structure and function of some PAS domains are revealed. We formerly detected a large number of PAS domains from the filamentous cyanobacterium Anabaena sp. PCC 7120, although most of them have no obvious similarity with the PAS domains of known function. To predict novel sensory PAS domains, we performed comparative genomics analysis with closely-related species. As a result, we extracted 25 putative sensory PAS domains. In the present study, we expressed and purified these 25 PAS domains as a His-tagged protein. Analyses of absorbance spectra and metal ions revealed novel ligand-binding PAS domains. Sensing mechanism of these ligand-binding PAS domains will be discussed.
