N-terminal S-acylation facilitates tonoplast targeting of the calcium sensor CBL6.

Protein S-acylation is important for many biological processes. It confers proteins with the ability to attach to the plasma membrane and the membranes confining the ER and Golgi compartments. Yet, the contribution of S-acylation to regulating and targeting lysosomal/vacuolar proteins remains largely enigmatic. Here, we report that vacuolar targeting of the calcium sensor calcineurin B-like protein 6 (CBL6) from Arabidopsis thaliana is brought about by S-acylation of N-terminal cysteine residues. Our results suggest distinctions in mechanisms and efficiency of targeting between CBL6 and the previously characterized vacuolar-targeted CBL2 protein. Moreover, we define which CBL-interacting protein kinases (CIPKs) could interact with CBL6 and observe a remarkable temperature dependence of CBL6/CIPK complex formation. Collectively, these findings indicate a common S-acyla tion-dependent vacuolar membrane targeting pathway for proteins.