Characterization of a High-Affinity Sialic Acid-Specific Cbm40 from Clostridium Perfringens and Engineering of a Divalent Form.
Ribeiro, J.P., Pau, W., Pifferi, C., Renaudet, O., Varrot, A., Mahal, L.K., Imberty, A.(2016) Biochem J 473: 2109
- PubMed: 27208171 
- DOI: https://doi.org/10.1042/BCJ20160340
- Primary Citation of Related Structures:  
5FRA, 5FRE - PubMed Abstract: 
CBMs (carbohydrate-binding modules) are a class of polypeptides usually associated with carbohydrate-active enzymatic sites. We have characterized a new member of the CBM40 family, coded from a section of the gene NanI from Clostridium perfringens Glycan arrays revealed its preference towards ¦Á(2,3)-linked sialosides, which was confirmed and quantified by calorimetric studies. The CBM40 binds to ¦Á(2,3)-sialyl-lactose with a Kd of ¡«30?¦ÌM, the highest affinity value for this class of proteins. Inspired by lectins' structure and their arrangement as multimeric proteins, we have engineered a dimeric form of the CBM, and using SPR (surface plasmon resonance) we have observed 6-11-fold binding increases due to the avidity affect. The structures of the CBM, resolved by X-ray crystallography, in complex with ¦Á(2,3)- or ¦Á(2,6)-sialyl-lactose explain its binding specificity and unusually strong binding.
Organizational Affiliation: 
Biomedical Chemistry Institute, New York University Department of Chemistry, 100 Washington Square East, Room 1001, New York, NY 10003, U.S.A. CERMAV, UPR5301, CNRS and Universit¨¦ Grenoble Alpes, 601 rue de la Chimie, BP 53, 38041, Grenoble, France.