Prenylation, the post-translational attachment of prenyl groups to substrate proteins, can affect their distribution and interactomes. ArabidopsisPLURIPETALA(PLP) encodes the shared α subunit of two heterodimeric protein isoprenyltransferases, whose functional loss provides a unique opportunity to study developmental and cellular processes mediated by its prenylated substrates, such as ROP GTPases. As molecular switches, the distribution and activation of ROPs are mediated by various factors, including guanine nucleotide exchange factors, GTPase activating proteins, guanine nucleotide dissociation inhibitors (RhoGDIs), prenylation, andS-acylation. However, how these factors together ensure that dynamic ROP signalling is still obscure. We report here that a loss-of-function allele ofPLPresulted in cytoplasmic accumulation of ROP2 in root hairs and reduced its stability. Consequently, two downstream events of ROP signalling, i.e. actin microfilament (MF) organization and the production of reactive oxygen species (ROS), were compromised. Genetic, cytological and biochemical evidence supports an additive interaction between prenylation and RhoGDI1/SCN1 in ROP2 distribution and stability whereas PLP acts synergistically with the proteinS-acyl transferase TIP GROWTH DEFECTIVE1 during root hair growth. By using root hair growth as a model system, we uncovered complex interactions among prenylation, RhoGDIs, andS-acylation in dynamic ROP signalling.Significance Statement
Post-translational modifications of proteins, especially lipid modifications such as prenylation and S-acylation, are important and mutants affected in such modifications exhibit developmental phenotypes. We used root hair growth as a model to uncover the complex interactions among prenylation, S-acylation, and RhoGDI1/SCN1 in the subcellular distribution and stability of ROP2 GTPases.