orals 5th Asia-Pacific NMR Symposium 2013

Effects of β-galactoside Binding on the Folding Stability and Dynamics of Human Galectins (#88)

Chih-Ta Henry Chien 1 2 3 , Tung-Ju Hsieh 1 , Shih-Hsiung Wu 1 2 3 , Chun-Hung Lin 1 3 , Shang-Te Danny Hsu 1 3
  1. Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
  2. Department of Chemistry, National Taiwan University, Taipei, Taiwan
  3. Institute of Biochemical Science, National Taiwan University, Taipei, Taiwan

Galectins are a family of lectins that interact with βgalactosides. There are 15 galectins that have been identified in cytosol, nucleus, and extracellular matrix, which are involved in a broad range of functions including cell-cell interaction, cell-matrix adhesion and transmembrane signaling. Although numerous crystal structures of galectins have been reported, it is difficult to rationalize the molecular recognition mechanism based on the minimum structural differences between the apo- and holo-forms. In this work, we investigate the chemical and thermal denaturation of galectin-1, -7, and -8 by intrinsic fluorescence, far UV CD, and differential scanning fluorimetry (DSF). Additionally, we use 15N spin relaxation dynamics and hydrogen-deuterium exchange experiments to probe the impacts of lactose binding on the internal dynamics of galectins. Our results show that ligand binding not only perturbs the direct binding sites but also results in long-range perturbations at the interface between the galectin monomers. Collectively, our results indicate that lactose binding can either increase or reduce the internal dynamics, as well as the folding stabilities of galectin-1, -7, -8. The differential responses of different galectins could potentially be exploited for inhibitor design with better specificity.