Figure 4

Fluorescence characterization of the global change of the C1 ring. (a) Trp-fluorescence spectra of KaiC^WT (black), KaiC^W92F (green), and KaiC^S229W (red) in the hexameric (solid lines) and monomeric forms (broken lines). Red and orange areas correspond to W229 fluorescence in the hexameric and monomeric forms, respectively. Gray and cyan regions correspond to W92 fluorescence in the hexameric and monomeric forms, respectively. (b) Zoomed-in stereo view of the C1–protomer interface of KaiC1^S229W (blue and green subunits, accession code: 5YZ8) superimposed onto KaiC1^WT (white subunits, accession code: 4TL7). W92 and W229 in KaiC1^S229W are drawn in red, and W92 in KaiC1^WT is drawn in white. The meshes represent the |F_o| − |F_c| difference Fourier maps for omitted side chains of H33 and W229 in KaiC1^S229W contoured at 2σ.