S-acylation in plants: an expanding field

Abstract

S-acylation is a common yet poorly understood fatty acid-based post-translational modification of proteins in all eukaryotes, including plants. While exact roles for S-acylation in protein function are largely unknown the reversibility of S-acylation indicates that it is likely able to play a regulatory role. As more studies reveal the roles of S-acylation within the cell it is becoming apparent that how S-acylation affects proteins is conceptually different from other reversible modifications such as phosphorylation or ubiquitination; a new mind-set is therefore required to fully integrate these data into our knowledge of plant biology. This review aims to highlight recent advances made in the function and enzymology of S-acylation in plants, highlights current and emerging technologies for its study and suggests future avenues for investigation.

A Calcium/Palmitoylation Switch Interfaces the Signaling Networks of Stress Response and Transition to Flowering

“…Eukaryotic palmitoyl-acyl transferases (PATs) of the DHHC (Asp-His-His-Cys) family catalyze protein S-acylation (Batistič, 2012;Hemsley, 2020). In turn, thioesterases break down the ester bond of S-acylation and release the fatty acid.…”

“…In turn, thioesterases break down the ester bond of S-acylation and release the fatty acid. The unique reversibility of protein S-acylation allows proteins to rapidly change their location between intracellular compartments (Aicart-Ramos et al, 2011;Hemsley, 2020). Conditional S-acylation is known to serve as lipid anchor at membranes to immobilize and restrain proteins from entering the nucleus (Hemsley, 2020;Eisenhaber et al, 2011;Lott et al, 2011).…”

“…Upon salinity stress, only cytoplasmic GI is degraded, thereby releasing SOS2 to mount the salt stress response, whereas nuclear GI remains stable in physical association with SOS3, eventually leading to flowering. Notably, S-acylation with fatty acids, commonly known as protein palmitoylation (Hemsley, 2020), of SOS3 is required for the nuclear import of SOS3 but dispensable for the interaction with GI. We also demonstrate the participation of SOS3 in the GI-FKF1 transcriptional complex that promotes transcription of CO, a crucial floral activator.…”

Distinct Roles of N-Terminal Fatty Acid Acylation of the Salinity-Sensor Protein SOS3

“…In S -acylation, a chain fatty acid, usually palmitic, covalently attaches to a cysteine residue via a thioester bond. A critical difference between these two protein acylations with fatty acids is that, whereas protein N -myristoylation is largely irreversible, S -acylation is a fully reversible post-translational modification, akin to protein phosphorylation, through the interplay of PATs and acyl-protein thioesterases (APTs; Hemsley, 2020 ). There is no clear consensus motif for the in silico identification of S -acylated proteins or S -acylation sites within a protein, the only exception being that a cysteine residue at position 3 next to a glycine in position 2 is often found to be associated with concurrent N -myristoylation and S -palmitoylation ( Hemsley et al, 2013 ; Castrec et al, 2018 ).…”

“…Knowledge on protein S -acylation and its consequences on protein function and trafficking is lagging behind that of myristoylation because of the recent discovery of PATs and the limited technical resources available to study S -acylation ( Li and Qi, 2017 ; Hemsley, 2020 ). The roles of S -acylation are still poorly understood, but they go certainly beyond the regulation of membrane association.…”