Split-Luciferase Complementation for Analysis of Virus-Host Protein Interactions.

Productive viral infection entails highly regulated and sequential protein-protein interactions between viral factors and between virus and host factors. Deciphering such interactions is of paramount importance for a better understanding of virus infection cycles and the development of new strategies for virus prevention and control. In this protocol, we describe a split-luciferase complementation (SLC ) assay for the detection of protein-protein interaction in Nicotiana benthamiana leaves following agroinfiltration-mediated transient protein expression. In this assay, the firefly luciferase protein is divided into two halves, each expressed as a fusion to a prey or bait protein, respectively. Interaction of the two candidate proteins brings the two otherwise nonfunctional halves into close proximity to restore the luciferase activity, which catalyzes the substrate D-luciferin to emit luminescence. The SLC assay allows for noninvasive, quantitative measurement of dynamic protein interactions in living cells within their native cellular compartments.