S-acylation is involved in tonoplast targeting of flax resistance protein M

Abstract

Several plant resistance proteins require accurate targeting to cellular membranes for effective pathogen defence function. The resistance protein variant M from Linum ussitatissimum (flax) protects plants against the flax rust disease and is specifically targeted to the vacuolar membrane. This localization mechanism involves the S-acylation of cysteine residues within the N-terminus of the protein. Moreover, the M S-acylation and targeting signal likely binds to membranes in the absence of lipid modifications and can switch from the vacuolar membrane to the plasma membrane depending on the S-acylation status. Importantly, plasma membrane targeting was observed when the short targeting signal from M was expressed in an Arabidopsis thaliana pat10 mutant plant. On the other hand, tonoplast localization of the N-terminal S-acylation domain was reconstituted in the mutant plant upon co-expression of two highly related PAT10 enzymes from flax. In contrast to the Golgi and tonoplast targeted Arabidopsis PAT10, the two homologous enzymes from flax mainly localized to the plasma membrane and were partially observed at the vacuolar membrane when expressed in flax as well as in Arabidopsis cells. This implicates that S-acylation of flax proteins could occur at the plasma membrane and that the lipid modification is required for subsequent routing to the vacuolar membrane, which could be also involved in the localization mechanism of M.Competing Interest StatementThe authors have declared no competing interest.View Full Text