Functional and structural bases of a cysteine-less mutant as a long-lasting substitute for galectin-1.
Galectin-1 (Gal-1), a member of the beta-galactoside-binding animal lectin family, has a wide range of biological activities, which makes it an attractive target for medical applications. Unlike other galectins, Gal-1 is susceptible to oxidation at cysteine residues, which is troublesome for in vitro/vivo studies. To overcome this problem, we prepared a cysteine-less mutant of Gal-1 (CSGal-1) by substituting all cysteine residues with serine residues. In the case of wild-type Gal-1, the formation of covalent dimers/oligomers was evident after 10 days of storage in the absence of a reducing agent with a concomitant decrease in hemagglutination activity, while CSGal-1 did not form multimers and retained full hemagglutination activity after 400 days of storage. Frontal affinity chromatography showed that the sugar-binding specificity and affinity of Gal-1 for model glycans were barely affected by the mutagenesis. Gal-1 is known to induce cell signaling leading to an increase in the intracytoplasmic calcium concentration and to cell death. CSGal-1 is also capable of inducing calcium flux and growth inhibition in Jurkat cells, which are comparable to or more potent than those induced by Gal-1. The X-ray structure of the CSGal-1/lactose complex has been determined. The structure of CSGal-1 is almost identical to that of wild-type human Gal-1, showing that the amino acid substitutions do not affect the overall structure or carbohydrate-binding site structure of the protein. These results indicate that CSGal-1 can serve as a stable substitute for Gal-1.
Nishi
Nozomu
N
Department of Endocrinology, Faculty of Medicine, Kagawa University, Kagawa, Japan. nnishi@med.kagawa-u.ac.jp
Abe
Akemi
A
Iwaki
Jun
J
Yoshida
Hiromi
H
Itoh
Aiko
A
Shoji
Hiroki
H
Kamitori
Shigehiro
S
Hirabayashi
Jun
J
Nakamura
Takanori
T
D019943:Amino Acid Substitution; D001665:Binding Sites; D049109:Cell Proliferation; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000235:genetics* / Q000378:metabolism; D037483:Galectin 1 / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D008562:Membrane Glycoproteins / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010084:Oxidation-Reduction; D011487:Protein Conformation; D013329:Structure-Activity Relationship
D037483:Galectin 1; D008562:Membrane Glycoproteins; D003545:Cysteine