Roles of N-Terminal Fatty Acid Acylations in Membrane Compartment Partitioning:Arabidopsis h-Type Thioredoxins as a Case Study  

Abstract

N-terminal fatty acylations (N-myristoylation [MYR] and S-palmitoylation [PAL]) are crucial modifications affecting 2 to 4% of eukaryotic proteins. The role of these modifications is to target proteins to membranes. Predictive tools have revealed unexpected targets of these acylations in Arabidopsis thaliana and other plants. However, little is known about how N-terminal lipidation governs membrane compartmentalization of proteins in plants. We show here that h-type thioredoxins (h-TRXs) cluster in four evolutionary subgroups displaying strictly conserved N-terminal modifications. It was predicted that one subgroup undergoes only MYR and another undergoes both MYR and PAL. We used plant TRXs as a model protein family to explore the effect of MYR alone or MYR and PAL in the same family of proteins. We used a high-throughput biochemical strategy to assess MYR of specific TRXs. Moreover, various TRX-green fluorescent protein fusions revealed that MYR localized protein to the endomembrane system and that partitioning between this membrane compartment and the cytosol correlated with the catalytic efficiency of the N-myristoyltransferase acting at the N terminus of the TRXs. Generalization of these results was obtained using several randomly selected Arabidopsis proteins displaying a MYR site only. Finally, we demonstrated that a palmitoylatable Cys residue flanking the MYR site is crucial to localize proteins to micropatching zones of the plasma membrane.

S‐acylation anchors remorin proteins to the plasma membrane but does not primarily determine their localization in membrane microdomains

“…Membrane domain localization of proteins in living cells can also be achieved by combinatorial lipidation, mainly myristoylation and S-acylation. In plants, double lipidation of h-type thioredoxins (TRX) was shown to target these proteins to membrane microdomains in planta (Traverso et al, 2013). By contrast, domain markers from A. thaliana and M. truncatula like flotillin and remorin proteins lack N-terminal glycine residues and are therefore not myristoylated.…”

Golgi Traffic and Integrity Depend on N-Myristoyl Transferase-1 in Arabidopsis

“…(Traverso et al, 2013a). b N-terminal octapeptides (from amino acids 2 to 9) were derived from Arabidopsis proteins for which MYR was previously predicted and/or reported (Traverso et al, 2013a(Traverso et al, , 2013b. The k cat /K m value reflects the catalytic efficiency of each peptide to be MYRed by the NMT enzyme.…”

“…Partitioning between the endomembrane compartment and the cytosol correlates with the catalytic efficiency of the N-myristoyltransferase (i.e., low NMT catalytic efficiency induces an increase in the soluble fraction of the MYRed protein substrate) (Traverso et al, 2013b). Therefore, we wondered whether, owing to the reduced in vitro myristoylase activity of NMT1A160T (Table 2), we would observe an effect of the STINGY mutation on the distribution and membrane binding of Arf-GTPases.…”

A Lipid-Anchored NAC Transcription Factor Is Translocated into the Nucleus and Activates Glyoxalase I Expression during Drought Stress

“…Confocal imaging revealed spots distributed around the nucleus, and these spots merged with the Golgi and ER marker protein MAN1 from soybean (Glycine max) (Traverso et al, 2013). By contrast, the wild-type MfNACsa protein localized to the membrane ( Figure 6C; Supplemental Figure 15A), showing that the C26S mutation caused MfNACsa ER/Golgi apparatus retention.…”