Abstract
AnPixJ is a novel cyanobacteriochrome of a cyanobacterium Anabaena (Nostoc) sp. PCC 7120. Upon the irradiation of red- light and green-light, it shows a reversible photoconversion between a green-absorbing (λmax=543 nm) and red-absorbing (λmax¬=648 nm) forms (1) . The crystallographic structure in the state of Pg is not understood though that in the state of Pr is understood (2) . His-tagged chromophore-binding GAF domain of AnPixJ protein (AnPixJ-GAF) with a molecular weight of about 20 kDa was purified by using Ni affinity column. Then, we illuminated the protein at 77 K and followed worming up to examine the reaction process. We succeeded to trap 4 intermediate states in the photoconversion process. The absorption spectra of these 4 states confirmed the ones measured by the time-resolved spectroscopy at room temperature. We discuss the photoconversion mechanism of this protein.
(1) Narikawa J.Mol.Biol. (2008) 380, 844-855
(2) Narikawa Acta Cryst. (2009). F65, 159-162
