Bimolecular Fluorescence Complementation - History

History

Biochemical complementation was first reported in subtilisin-cleaved bovine pancreatic ribonuclease, then expanded using β-galactosidase mutants that allowed cells to grow on lactose.

Recognition of many proteins' ability to spontaneously assemble into functional complexes as well as the ability of protein fragments to assemble as a consequence of the spontaneous functional complex assembly of interaction partners to which they are fused was later reported for ubiquitin fragments in yeast protein interactions.

In 2000, Ghosh et al developed a system that allowed a green fluorescent protein (GFP) to be reassembled using an anti-parallel leucine zipper in E. coli cells. This was achieved by dissecting GFP into C- and N-terminal GFP fragments. As the GFP fragment was attached to each leucine zipper by a linker, the heterodimerisation of the anti-parallel leucine zipper resulted in a reconstituted, or re-formed, GFP protein that could be visualised. The successful fluorescent signal indicated that the separate GFP peptide fragments were able to correctly reassemble and achieve tertiary folding. It was, therefore, postulated that using this technique, fragmented GFP could be used to study interaction of protein–protein pairs that have their N-C termini in close proximity.

After the demonstration of successful fluorescent protein fragment reconstitution in mammalian cells, Hu et al. described the use of fragmented yellow fluorescent protein (YFP) in the investigation of bZIP and Rel family transcription factor interactions. This was the first report bZIP protein interaction regulation by regions outside of the bZIP domain, regulation of subnuclear localization of the bZIP domains Fos and Jun by their different interacting partners, and modulation of transcriptional activation of bZIP and Rel proteins through mutual interactions. In addition, this study was the first report of an in vivo technique, now known as the bimolecular fluorescence complementation (BiFC) assay, to provide insight into the structural basis of protein complex formation through detection of fluorescence caused by the assembly of fluorescent reporter protein fragments tethered to interacting proteins.