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Published on: July 5, 2018
Characterization of a high-affinity sialic acid-specific CBM40 from Clostridium perfringens and engineering of a
João P Ribeiro1, William Pau2, Carlo Pifferi3
1Biomedical 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 Université Grenoble Alpes, 601 rue de la Chimie, BP 53, 38041, Grenoble, France.
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 α(2,3)-linked sialosides, which was confirmed and quantified by calorimetric studies. The CBM40 binds to α(2,3)-sialyl-lactose with a Kd of ∼30 μM, 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 α(2,3)- or α(2,6)-sialyl-lactose explain its binding specificity and unusually strong binding.
