An Arabidopsis Protein-Flavonoid Interactome Identifies Peroxiredoxin A as a Candidate for Flavonoid Action in Chloroplasts.

The ability of phytochemicals to act as small molecule effectors of protein function is a largely overlooked dimension of plant biochemistry. This is particularly true for the ubiquitous flavonoids where, despite abundant examples of functional interactions with human proteins, biological activities in plants are primarily attributed to ROS scavenging. We used affinity capture to explore the protein interactome of the flavonoid glycoside, rutin, in Arabidopsis seedlings. Unexpectedly, the 397 high-confidence candidates included numerous proteins associated with chloroplasts, where flavonoids are present at exceedingly low levels. Intriguingly, several identified targets are conserved with known flavonoid-interacting proteins in mammals, where the bioavailability of flavonoids is similarly low. Using one of these, the Arabidopsis plastidial 2-cys peroxiredoxin A, as a test case, this study substantiated the potential of affinity proteomics for identifying novel protein targets of phytochemicals and suggests that flavonoids modulate protein function in plants to a larger extent than previously suspected.