title: Cyanobacterial phytochrome Cph2 is a negative regulator in phototaxis toward UV-A.
abstract: We investigated the wavelength dependence and photon-fluence rate response relationship for phototaxis of wild-type and a cyanobacterial phytochrome 2 (cph2) mutant in cyanobacterium Synechocystis sp. PCC 6803. Compared to wild-type, the cph2 mutant exhibited maximal activity for positive phototaxis at the near-UV spectral range. Two cysteine to serine substitutions in two chromophore-binding domains showed a similar cph2 mutant phenotype under UV-A. Epistasis of a pixJ mutation over a cph2 mutation implied that pixJ gene acts downstream of the cph2 gene with respect to UV-A-induced positive phototaxis. Therefore, we suggest that Cph2 is essential for the inhibition of positive phototaxis toward UV-A.
authors.affiliation: Division of Life Science, Korea Basic Science Institute, Daejeon, Republic of Korea.
authors.forename: Yoon-Jung
authors.initials: YJ
authors.lastname: Moon
authors.forename: Soo Youn
authors.initials: SY
authors.lastname: Kim
authors.forename: Kwang-Hwan
authors.initials: KH
authors.lastname: Jung
authors.forename: Jong-Soon
authors.initials: JS
authors.lastname: Choi
authors.forename: Young Mok
authors.initials: YM
authors.lastname: Park
authors.forename: Young-Ho
authors.initials: YH
authors.lastname: Chung
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry / Q000502:physiology* / Q000528:radiation effects; D004843:Epistasis, Genetic; D009154:Mutation; D010834:Phytochrome / Q000502:physiology*; D046939:Synechocystis; D014466:Ultraviolet Rays
chemical_list: D010834:Phytochrome