Galectin‐1–Asialofetuin Interaction Is Inhibited by Peptides Containing the Tyr‐Xxx‐Tyr Motif Acting on the Glycoprotein

Abstract

Galectin-1 (Gal-1), a ubiquitous beta-galactoside-binding protein expressed by various normal and pathological tissues, has been implicated in cancer and autoimmune/inflammatory diseases in consequence of its regulatory role in adhesion, cell viability, proliferation, and angiogenesis. The functions of Gal-1 depend on its affinity for beta-galactoside-containing glycoconjugates; accordingly, the inhibition of sugar binding blocks its functions, hence promising potential therapeutic tools. The Tyr-Xxx-Tyr peptide motifs have been reported to be glycomimetic sequences, mainly on the basis of their inhibitory effect on the Gal-1-asialofetuin (ASF) interaction. However, the results regarding the efficacy of the Tyr-Xxx-Tyr motif as a glycomimetic inhibitor are still controversial. The present STD and trNOE NMR experiments reveal that the Tyr-Xxx-Tyr peptides studied do not bind to Gal-1, whereas their binding to ASF is clearly detected. (15)N,(1)H HSQC titrations with (15)N-labeled Gal-1 confirm the absence of any peptide-Gal-1 interaction. These data indicate that the Tyr-Xxx-Tyr peptides tested in this work are not glycomimetics as they interact with ASF via an unrevealed molecular linkage.

Galectin-1 as a fusion partner for the production of soluble and folded human β-1,4-galactosyltransferase-T7 in E. coli

“…These observations are consistent with the hypothesis that the carbohydrate-binding domain plays an important role in assisting the folding of the carrier protein by involving hydrogen bonding and hydrophobic interactions in the CRD pocket during folding process. This is further supported by the observation that the peptides with a core sequence of Tyr-Xxx-Tyr can bind to CRD of galectin-1 [32], suggesting that the CRD domain has a potential to form CH-π stacking interactions, which play a role in the folding of proteins.…”

Routing Nanomolar Protein Cargoes to Lipid Raft‐Mediated/Caveolar Endocytosis through a Ganglioside GM1‐Specific Recognition Tag

“…The lead molecule WYKYW ( Figure ) was first identified by Gabius and coworkers as a member of the Tyr‐Xxx‐Tyr‐containing pentapeptide family, which was observed to decouple galectin‐1 and proteoglycan interactions . Subsequently, we showed that the mechanism of inhibition of the proteoglycan–galectin‐1 interaction is a competitive binding of the peptide at the glycan moiety of asialofetuin . Knowing that galectin‐1 binds to ganglioside GM1, we hypothesized that WYKYW also interacts with the extracellular glycan moiety of GM1.…”

Intracellular protein delivery with the use of endocytosis routing sequences

“…With the use of saturation transfer difference (STD) and transferred nuclear Overhauser effect (trNOE) nuclear magnetic resonance (NMR) measurements, our research group showed that this decoupling arises from the competitive binding of the pentapeptide and the galectin-1 at the glycan moiety of asialofetuin. 150 Starting from this experiment, and knowing that ganglioside GM1 is the major receptor of galectin-1, we hypothesized an interaction between WYKYW and the carbohydrate moiety of GM1 (Figure 7). 151 To that end, the pentapeptide and its derivatives were synthesized with Fmoc chemistry, purified with HPLC, and their affinity and specificity to different gangliosides were measured using isothermal titration calorimetry (ITC) and NMR.…”