Structure and functional analysis of the fungal galectin CGL2.
Recognition of and discrimination between potential glyco-substrates is central to the function of galectins. Here we dissect the fundamental parameters responsible for such selectivity by the fungal representative, CGL2. The 2.1 A crystal structure of CGL2 and five substrate complexes reveal that this prototype galectin achieves increased substrate specificity by accommodating substituted oligosaccharides of the mammalian blood group A/B type in an extended binding cleft. Kinetic studies on wild-type and mutant CGL2 proteins demonstrate that the tetrameric organization is essential for functionality. The geometric constraints due to the orthogonal orientation of the four binding sites have important consequences on substrate binding and selectivity.
Walser
Piers J
PJ
Institute of Microbiology, Swiss Federal Institute of Technology, Schmelzbergstrasse 7, CH-8092, Zurich, Switzerland.
Haebel
Peter W
PW
Künzler
Markus
M
Sargent
David
D
Kües
Ursula
U
Aebi
Markus
M
Ban
Nenad
N
D001665:Binding Sites; D002850:Chromatography, Gel; D003302:Coprinus / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005697:Galactosides / Q000378:metabolism; D037501:Galectin 2; D037161:Galectins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
C103751:CGL2 protein, Coprinus cinereus; D005656:Fungal Proteins; D005697:Galactosides; D037501:Galectin 2; D037161:Galectins