Simultaneous visualization of two protein complexes in a single plant cell using multicolor fluorescence complementation analysis

Bimolecular fluorescence complementation (BiFC) is an approach used to analyze protein–protein interaction in vivo, in which non-fluorescent N-terminal and C-terminal fragments of a fluorescent protein are reconstituted to emit fluorescence only when they are brought together by interaction of two proteins to fuse both fragments. A method for simultaneous visualization of two protein complexes by multicolor BiFC with fragments from green fluorescent protein (GFP) and its variants such as cyan and yellow fluorescent proteins (CFP and YFP) was recently reported in animal cells. In this paper we describe a new strategy for simultaneous visualization of two protein complexes in plant cells using the multicolor BiFC with fragments from CFP, GFP, YFP and a red fluorescent protein variant (DsRed-Monomer). We identified nine different BiFC complexes using fragments of CFP, GFP and YFP, and one BiFC complex using fragments of DsRed-Monomer. Fluorescence complementation did not occur by combinations between fragments of GFP variants and DsRed-Monomer. Based on these findings, we achieved simultaneous visualization of two protein complexes in a single plant cell using two colored fluorescent complementation pairs (cyan/red, green/red or yellow/red).