A multidimensional “omics” approach reveals biased signaling through flg22- and UDP-glucose-induced, AtRGS1-driven signaling circuits

Different cellular inputs into a central signaling core elicit different outputs in a process called biased signaling. Often this occurs by imprinting the signaling core with a phosphorylation bar code, functionally analogous to a microprocessor. The bacterial peptide flg22 and UDP-glucose both utilize a heterologous G protein core that contains a 7-transmembrane RGS protein, AtRGS1, to mediate changes differentially in plant defense and growth. Both flg22 and UDP-glucose launch rapid endocytosis of AtRGS1 at the plasma membrane but the destination and route are signal specific. flg22 directs plasma membrane AtRGS1 to the nucleus followed by different gene expression profiles. UDP-glucose does not direct AtRGS1 to the nucleus and does not elicit transcriptional reprogramming. Instead, UDP-glucose causes a massive, time-dependent restructuring of the G protein complex that likely traffics to the endosomal compartment. Associated with these two outcomes are phosphorylation bar codes that correlate with different patterns of AtRGS1-associated partners over time.