FIGURE 6.

Molecular modeling of Clomeleon. The fluorescent domains, CFP (cyan) and Topaz (yellow) were set in parallel orientation since N- and C-terminal ends of either domain were on the same site. The intramolecular distance between CFP and Topaz chromophores was calculated to be 3.3 nm. A more compact antiparallel or crosslike orientation with distances close to 2.6 nm as found in homolog experimental structures sterically hindered the placement of the rTEV site containing linker without unfolding the adjacent helices of the fluorescent domains (data not shown).