摘要：Light-Oxygen-Voltage (LOV) domains are responsible for detecting blue light (BL) and regulating the activities of effector domains in various organisms. Photozipper (PZ), an N-terminally truncated aureochrome-1 protein, contains a LOV domain and a basic leucin zipper (bZIP) domain and plays a role as a light-activatable transcription factor. PZ is monomeric in the dark state and undergoes non-covalent dimerization upon illumination with BL, subsequently increasing its affinity for the target DNA. To clarify the molecular mechanism of aureochromes, we prepared site-directed mutants of PZ and performed quantitative analyses in the dark and light states. Although the amino acid substitutions in the hinge region between the LOV core and A’
α helix had minor effects on the dimerization and DNA-binding properties of PZ, the substitutions in the
β-sheet region of the LOV core and in the A’
α helix significantly affected these properties. We found that light signals are transmitted from the LOV core to the effector bZIP domain via the hydrophobic residues on the
β-sheet. The light-induced conformational change possibly deforms the hydrophobic regions of the LOV core and induces the detachment of the A’
α helix to expose the dimerization surface, likely activating the bZIP domain in a light-dependent manner.
