Galectin-3 N-terminal tail prolines modulate cell activity and glycan-mediated oligomerization/phase separation

作者：Zihan Zhao, Xuejiao Xu, Hairong Cheng, Michelle C. Miller, Zhen He, Hongming Gu, Zhongyu Zhang, Avraham Raz, Kevin H. Mayo, Guihua Tai, Yifa Zhou · 发表于：Proceedings of the National Academy of Sciences · 年份：2021 · DOI：10.1073/pnas.2021074118 · 被引用次数：69 · 研究领域：Galectins and Cancer Biology、Protein Tyrosine Phosphatases、Signaling Pathways in Disease

Galectin-3 (Gal-3) has a long, aperiodic, and dynamic proline-rich N-terminal tail (NT). The functional role of the NT with its numerous prolines has remained enigmatic since its discovery. To provide some resolution to this puzzle, we individually mutated all 14 NT prolines over the first 68 residues and assessed their effects on various Gal-3-mediated functions. Our findings show that mutation of any single proline (especially P37A, P55A, P60A, P64A/H, and P67A) dramatically and differentially inhibits Gal-3-mediated cellular activities (i.e., cell migration, activation, endocytosis, and hemagglutination). For mechanistic insight, we investigated the role of prolines in mediating Gal-3 oligomerization, a fundamental process required for these cell activities. We showed that Gal-3 oligomerization triggered by binding to glycoproteins is a dynamic process analogous to liquid-liquid phase separation (LLPS). The composition of these heterooligomers is dependent on the concentration of Gal-3 as well as on the concentration and type of glycoprotein. LLPS-like Gal-3 oligomerization/condensation was also observed on the plasma membrane and disrupted endomembranes. Molecular- and cell-based assays indicate that glycan binding-triggered Gal-3 LLPS (or LLPS-like) is driven mainly by dynamic intermolecular interactions between the Gal-3 NT and the carbohydrate recognition domain (CRD) F-face, although NT-NT interactions appear to contribute to a lesser extent. Mutation of each proline ...