Abstract
AppA is a new-class blue-light receptor controlling photosynthesis gene expression in the purple bacterium Rhodobacter sphaeroides, and retains a FAD-binding domain BLUF in its N-terminus. Blue-light perception in AppA BLUF domain induces re-arrangement of hydrogen bond network between FAD and apo-protein. This change in the hydrogen bond network further induces a conformation change in the β-sheet structure of AppA BLUF domain. It is proposed that the light-dependent conformation change in the β-sheet structure is critical for transforming light signal from chromophore to the associated transcriptional factor PpsR. The mechanism of light-dependent signal transduction pathway in AppA and PpsR will be discussed.
