Novel binding site identified in a hybrid between cholera toxin and heat-labile enterotoxin: 1.9 A crystal structure reveals the details.
Journal article, 2004
A hybrid between the B subunits of cholera toxin and Escherichia coli heat-labile enterotoxin has been described, which exhibits a novel binding specificity to blood group A and B type 2 determinants. In the present investigation, we have determined the crystal structure of this protein hybrid, termed LCTBK, in complex with the blood group A pentasaccharide GalNAcalpha3(Fucalpha2)Galbeta4(Fucalpha3)GlcNAcbeta, confirming not only the novel binding specificity but also a distinct new oligosaccharide binding site. Binding studies revealed that the new specificity can be ascribed to a single mutation (S4N) introduced into the sequence of Escherichia coli heat-labile enterotoxin. At a resolution of 1.9 A, the new binding site is resolved in excellent detail. Main features include a complex network of water molecules, which is well preserved by the parent toxins, and an unexpectedly modest contribution to binding by the critical residue Asn4, which interacts with the ligand only via a single water molecule.
Water
metabolism
X-Ray
Asparagine
metabolism
genetics
chemistry
chemistry
Humans
Molecular Structure
genetics
Molecular
Escherichia coli Proteins
Enterotoxins
genetics
chemistry
Protein Structure
Crystallography
Drug Design
Blood Group Antigens
Bacterial Toxins
genetics
chemistry
chemistry
metabolism
metabolism
chemistry
metabolism
Recombinant Fusion Proteins
metabolism
Protein Binding
metabolism
Tertiary
genetics
genetics
metabolism
metabolism
Cholera Toxin
chemistry
Protein Subunits
Oligosaccharides
Models
Glycosphingolipids
Binding Sites
chemistry
chemistry
metabolism
Molecular Sequence Data
Author
Åsa Holmner
Chalmers
Michael Lebens
University of Gothenburg
Susann Teneberg
University of Gothenburg
Jonas Ångström
University of Gothenburg
M. Ökvist
University of Gothenburg
Ute Krengel
Chalmers, Department of Chemistry and Bioscience
Structure
0969-2126 (ISSN) 18784186 (eISSN)
Vol. 12 9 1655-67Subject Categories
MEDICAL AND HEALTH SCIENCES
DOI
10.1016/j.str.2004.06.022
PubMed
15341730