S-Palmitoylation and S-Oleoylation of Rabbit and Pig Sarcolipin [Membrane Biology]

October 9th, 2014 by Montigny, C., Decottignies, P., le Marechal, P., Capy, P., Bublitz, M., Olesen, C., Moller, J. V., Nissen, P., le Maire, M.

Sarcolipin (SLN) is a regulatory peptide present in sarcoplasmic reticulum (SR) from skeletal muscle of animals. We find that native rabbit SLN is modified by a fatty acid anchor on Cys9 with a palmitic acid in about 60% and, surprisingly, an oleic acid in the remaining 40%. SLN used for co-crystallization with SERCA1a (1) is also palmitoylated/oleoylated, but is not visible in crystal structures, probably due to disorder. Treatment with 1 M hydroxylamine for 1 hour removes the fatty acids from a majority of the SLN pool. This treatment did not modify the SERCA1a affinity for Ca2+ but increased the Ca2+-dependent ATPase activity of SR membranes indicating that the S-acylation of SLN or of other proteins is required for this effect on SERCA1a. Pig SLN is also fully palmitoylated/oleoylated on its Cys9 residue, but in a reverse ratio of about 40/60. An alignment of 67 SLN sequences from the protein databases shows that 19 of them contain a cysteine and the rest a phenylalanine at position 9. Based on a cladogram we postulate that the mutation from phenylalanine to cysteine in some species is the result of an evolutionary convergence. We suggest that, besides phosphorylation, S-acylation/deacylation also regulates SLN activity.