Download MendeleyGalectin-8 binding to alpha-1 antitrypsin is a physiological mechanism in healthy individuals but exacerbates the symptoms of alpha-1 antitrypsin deficiency.
Sayed, H., Mayo, K.H., Zhou, Y., Tai, G., Su, J.(2025) Arch Biochem Biophys 772: 110577-110577
- PubMed: 40780418
- DOI: https://doi.org/10.1016/j.abb.2025.110577
- Primary Citation of Related Structures:
9KH4 - PubMed Abstract:
Alpha-1 Antitrypsin (AAT) is a serine protease inhibitor that protects lung tissue by neutralizing neutrophil elastase. Galectin-8 (Gal-8) is a tandem-repeat galectin with N- and C-terminal carbohydrate recognition domains (CRDs) that bind β-galactoside-containing N-glycans. Both proteins co-localize in pulmonary and circulatory systems, suggesting a physiological interaction. Here, we demonstrate a glycan-dependent binding between Gal-8 and AAT using pull-down assays, mass spectrometry, isothermal titration calorimetry, and size-exclusion chromatography. Importantly, binding of Gal-8 impairs AAT's protease inhibitory activity, with the N-terminal CRD of Gal-8 sufficient to disrupt AAT function. Kinetic analyses show that Gal-8 inhibits AAT and enhances trypsin activity, as evidenced by a decrease in K m and an increase in catalytic efficiency (k cat /K m ). In cell assays, Gal-8 restored trypsin-mediated proteolysis and induced cell detachment in HeLa and CHO cells despite AAT presence, confirming biological relevance. Leveraging this interaction, we developed a lactose-mediated elution method to purify AAT from human and bovine serum using Gal-8 immobilized on Ni-NTA beads. Moreover, a stable CHO cell line expressing recombinant AAT (∼2 g/L) exhibited glycosylation comparable to serum AAT and retained Gal-8 binding. Our findings reveal Gal-8 as a novel modulator of AAT activity and present a glycan-specific strategy for AAT purification, with implications for biotherapeutic production and quality control.
- Engineering Research Center of Glycoconjugates Ministry of Education, Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun, 130024, China.
Organizational Affiliation:
