Date Published: November 01, 2016
Publisher: International Union of Crystallography
Author(s): Francesco Manzoni, Kadhirvel Saraboji, Janina Sprenger, Rohit Kumar, Ann-Louise Noresson, Ulf J. Nilsson, Hakon Leffler, S. Zoë Fisher, Tobias E. Schrader, Andreas Ostermann, Leighton Coates, Matthew P. Blakeley, Esko Oksanen, Derek T. Logan.
Perdeuteration, purification and the growth of large crystals of the carbohydrate-recognition domain of galectin-3C are described. Five neutron diffraction data sets have been collected at four neutron sources; these are compared and two are merged.
Galectins are a family of proteins defined by a carbohydrate-recognition domain (CRD) of about 130 residues with affinity for galactose-containing glycans (Leffler et al., 2002 ▸). Galectin-3 is one of the best known and most studied of the mammalian galectins (about 15 in total), and has multiple cellular functions in the nucleus and cytosol, inside vesicles and extracellularly. In the latter two compartments the CRD can interact with β-galactoside-containing glycoproteins and glycolipids, leading to important roles in regulation of membrane trafficking, signalling and cell adhesion (Rabinovich et al., 2007 ▸; MacKinnon et al., 2008 ▸; Delacour et al., 2009 ▸; Liu & Rabinovich, 2010 ▸; Funasaka et al., 2014 ▸). For example, galectin-3 plays an important role in tumour cell adhesion, differentiation, proliferation, metastasis and angiogenesis (Liu & Rabinovich, 2005 ▸). Galectin-3 has also been found to be involved in other diseases, such as idiopathic pulmonary fibrosis, a degenerative and lethal disease that occurs primarily in middle-aged and older adults (MacKinnon et al., 2012 ▸).
We have shown that it is possible to obtain large, high-quality perdeuterated crystals of the medically important carbohydrate-binding protein galectin-3C, interacting with different ligands and in a truly apo form, through macroseeding, repeated feeding and dialysis. Preliminary analysis of the structures showed a clear hydrogen-bonding network between the ligand and the protein. We showed in addition that it is possible to merge data successfully from two different neutron sources, resulting in a more complete data set. We believe that the detailed structural results, which will be presented elsewhere, may be useful for the development of better interacting ligands for galectin-3 and, in general, fruitful knowledge for the neutron crystallography and the drug-design field.