Structural Studies of Rice Phytochrome B PAS1 Domain Using Multi-Dimensional NMR

Abstract

Phytochrom B (phyB) is a dimeric chromoprotein that detects the quantity, quality, and duration of red or far-red light throughout the entire life cycle of plants. Upon absorption of red light, phyB translocates from the cytoplasm to nucleus, and regulates gene expression through interaction with transcription factors such as basic-helix-loop-helix proteins. The PAS domain within the phyB C-terminal domain contains determinants necessary for nuclear translocation and signal transduction. Here we showed the solution structure of PAS1 domain, one of two PAS domains, determined by multidimensional NMR spectroscopy. The structure of a loss of function missense mutant was partially denatured. Our structural and biochemical data revealed that the N-terminal region of the PAS1 domain is necessary to form homodimer, and the PAS1 domain does not interact with the other PAS domain, PAS2.