[1P-61*] High-speed AFM observation on the blue light-induced dimer formation of the transcription factor, Photozipper
Many transcription factors (TF), a family of DNA-binding proteins regulating various gene expressions, form dimers when they bind to DNA. Photozipper (PZ) is a TF consisting of a basic leucine zipper DNA binding (bZIP) domain and a light-oxygen-voltage-sensing (LOV) domain. Biochemical studies suggest that blue light (BL) induces dimerization of PZ and enhances its affinity for the target sequence. To understand the single-molecular dynamics of the BL-induced dimerization in PZ, we performed high-speed AFM (HS-AFM) observations of PZ molecules under the dark and light states.
HS-AFM visualized monomeric and dimeric forms of PZ molecules diffusing on mica in buffer solution. PZ monomers and dimers were predominantly found in the dark and light states, respectively. Interestingly, the lifetimes of PZ dimer were longer in the light state than that in the dark state. HS-AFM also revealed high-resolution structures of PZ, in which the distances from LOV to bZIP termini were longer in the light state than that in the dark state. These results suggest that the BL-induced conformational change extends the PZ molecule and contributes to stabilizing the dimer form of PZ.
HS-AFM visualized monomeric and dimeric forms of PZ molecules diffusing on mica in buffer solution. PZ monomers and dimers were predominantly found in the dark and light states, respectively. Interestingly, the lifetimes of PZ dimer were longer in the light state than that in the dark state. HS-AFM also revealed high-resolution structures of PZ, in which the distances from LOV to bZIP termini were longer in the light state than that in the dark state. These results suggest that the BL-induced conformational change extends the PZ molecule and contributes to stabilizing the dimer form of PZ.