3AJ5

HA1 (HA33) subcomponent of botulinum type C progenitor toxin complexed with N-acetylgalactosamine, bound at site II

Summary for 3AJ5

• Entry DOI: 10.2210/pdb3aj5/pdb
• Related: 3AH1 3AH2 3AH4 3AJ6
• Descriptor: Main hemagglutinin component, 2-acetamido-2-deoxy-beta-D-galactopyranose (3 entities in total)
• Functional Keywords: toxin, beta-trefoil, hemagglutinin
• Biological source: Clostridium botulinum
• Total number of polymer chains: 2
• Total formula weight: 68001.39

Authors

Nakamura, T.,Tonozuka, T.,Sato, R.,Oguma, K.,Nishikawa, A. (deposition date: 2010-05-24, release date: 2011-06-01, Last modification date: 2023-11-01)

Primary citation

Nakamura, T.,Tonozuka, T.,Ito, S.,Takeda, Y.,Sato, R.,Matsuo, I.,Ito, Y.,Oguma, K.,Nishikawa, A.
Molecular diversity of the two sugar-binding sites of the beta-trefoil lectin HA33/C (HA1) from Clostridium botulinum type C neurotoxin
Arch.Biochem.Biophys., 512:69-77, 2011

PubMed Abstract: A critical role in internalizing the Clostridium botulinum neurotoxin into gastrointestinal cells is played by nontoxic components complexed with the toxin. One of the components, a β-trefoil lectin has been known as HA33 or HA1. The HA33 from C. botulinum type A (HA33/A) has been predicted to have a single sugar-binding site, while type C HA33 (HA33/C) has two sites. Here we constructed HA33/C mutants and evaluated the binding capacities of the individual sites through mucin-assay and isothermal titration calorimetry. The mutant W176A (site I knockout) had a K(d) value of 31.5mM for galactose (Gal) and 61.3mM for N-acetylgalactosamine (GalNAc), while the K(d) value for N-acetylneuraminic acid (Neu5Ac) was too high to be determined. In contrast, the double mutant N278A/Q279A (site II knockout) had a K(d) value of 11.8mM for Neu5Ac. We also determined the crystal structures of wild-type and the F179I mutant in complex with GalNAc at site II. The results suggest that site I of HA33/C is quite unique in that it mainly recognizes Neu5Ac, and site II seems less important for the lectin specificity. The architectures and the properties of the sugar-binding sites of HA33/C and HA33/A were shown to be drastically different.

PubMed: 21640703
DOI: 10.1016/j.abb.2011.05.012

Experimental method

X-RAY DIFFRACTION (1.8 Å)