A novel role of 3,5-cAMP in the regulation of actin cytoskeleton in Arabidopsis.

Abstract

The role of cyclic adenosine monophosphate (3,5-cAMP) in plants is not well understood, and here, we report a novel role of 3,5-cAMP in regulating the actin cytoskeleton. The 3,5-cAMP treatment affects the thermal stability of 51 proteins, including a vegetative actin isoform, ACTIN2. Consistent with the above results, the increase in 3,5-cAMP levels, obtained either by feeding or by chemical modulation of 3,5-cAMP metabolism, is sufficient to partially rescue the short hypocotyl phenotype of the actin2 actin7 mutant, severely compromised in actin level. No such complementation was measured for a positional isomer of 3,5-cAMP, 2,3-cAMP, attesting to the specificity of 3,5-cAMP treatment. Moreover, supplementation of 3,5-cAMP partly counters the activity of an actin-depolymerizing drug latrunculin B. In vitro characterization of the 3,5-cAMP - actin interaction argues against the direct binding. Instead, based on the proteomics characterization of the act2act7 mutant supplemented with 3,5-cAMP, we hypothesize that 3,5-cAMP affects cytoskeleton dynamic by modulation of calcium signaling, and actin binding proteins.