Protein-protein complexation in bioluminescence

Abstract

In this review we summarize the progress made towards understanding the role of protein-protein interactions in the function of various bioluminescence systems of marine organisms, including bacteria, jellyfish and soft corals, with particular focus on methodology used to detect and characterize these interactions. In some bioluminescence systems, protein-protein interactions involve an "accessory protein" whereby a stored substrate is efficiently delivered to the bioluminescent enzyme luciferase. Other types of complexation mediate energy transfer to an "antenna protein" altering the color and quantum yield of a bioluminescence reaction. Spatial structures of the complexes reveal an important role of electrostatic forces in governing the corresponding weak interactions and define the nature of the interaction surfaces. The most reliable structural model is available for the protein-protein complex of the Ca 2+ -regulated photoprotein clytin and green-fluorescent protein (GFP) from the jellyfish Clytia gregaria, solved by means of Xray crystallography, NMR mapping and molecular docking. This provides an example of the potential strategies in studying the transient complexes involved in bioluminescence. It is emphasized that structural studies such as these can provide valuable insight into the detailed mechanism of bioluminescence.

Perspectives on Bioluminescence Mechanisms

“…The effect is less with obelin and Clytia GFP, suggesting specificity in the interaction, as also observed with the above mentioned other cases . The same argument used previously was that the spectral effect at these concentrations of Clytia GFP implied the presence of a protein–protein complex with K D in the μ m range but a search using standard methods, analytical ultracentrifugation, size‐exclusion chromatography, surface plasmon resonance or polarization fluorometry, failed to detect any complex with a K D < 100 μ m .…”

“…4, upper left), H-bonding is inferred at the distal C2-peroxy oxygen to a proximal side group of Tyr190 (Y190), which is bifurcated to the imidazole Ne of His-175 (106). A similar picture is evident in the structures of aequorin and other Ca 2+ -regulated photoproteins (63,129,130,(135)(136)(137).…”

“…6). In addition, as the GFP is dimeric, the active complex can accommodate two clytins and might naturally occur as a heterotetramer (63,84,129).…”

Monitoring G protein-coupled receptor and β-arrestin trafficking in live cells using enhanced bystander BRET

“…On the other hand, the natural combination of Rluc and GFP from Renilla reniformis (rGFP), which self-associate with moderate affinity and optimally transfer energy 10 17 18 , have been used as BRET pair to improve signal 10 19 . Here we took advantage of the characteristics of these naturally interacting chromophores from Renilla reniformis to develop new, highly dynamic BRET-trafficking sensors (herein after referred to as ‘enhanced bystander BRET' or EbBRET).…”

Fluorescent Protein–photoprotein Fusions and Their Applications in Calcium Imaging

“…Likewise, in the avGFP‐obelin fusion mentioned earlier, no evidence of a transient interaction was found . It appears that, when the photoprotein and GFP have coevolved, there is an interaction favoring BRET, as it was also found in vitro in the Clytia system , whereas the use of photoproteins and FPs from distantly related organisms weakens energy transfer. Even though such interaction in these BRET systems is weak and transient, it is still naturally specific and not interchangeable.…”