Transient-state kinetic analysis of complex formation between photoprotein clytin and GFP from jellyfish Clytia gregaria.

Luminous organisms use different protein-mediated strategies to modulate light emission color. Here, we report the transient-state kinetic studies of the interaction between photoprotein clytin from Clytia gregaria and its antenna protein, cgre GFP. We propose that cgre GFP forms a transient complex with Ca2+-bound clytin before the excited singlet state of the coelenteramide product is formed. From the spectral distribution and donor-acceptor separation distance, we infer that clytin reaction intermediates may interact only with the middle side part of cgre GFP. [ABSTRACT FROM AUTHOR]