Alteration of the Carbohydrate-Binding Specificity of a C-type Lectin CEL-I Mutant with an EPN Carbohydrate-Binding Motif

Author(s): Tomomitsu Hatakeyama, Tomohiro Ishimine, Tomohiro Baba, Masanari Kimura, Hideaki Unno, Shuichiro Goda.

Journal Name: Protein & Peptide Letters

Volume 20 , Issue 7 , 2013

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CEL-I is a Gal/GalNAc-specific C-type lectin isolated from the sea cucumber Cucumaria echinata. This lectin is composed of two carbohydrate-recognition domains (CRDs) with the carbohydrate-recognition motif QPD (Gln-Pro- Asp), which is generally known to exist in galactose-specific C-type CRDs. In the present study, a mutant CEL-I with EPN (Glu-Pro-Asn) motif, which is thought to be responsible for the carbohydrate-recognition of mannose-specific Ctype CRDs, was produced in Escherichia coli, and its effects on the carbohydrate-binding specificity were examined using polyamidoamine dendrimer (PD) conjugated with carbohydrates. Although wild-type CEL-I effectively formed complexes with N-acetylgalactosamine (GalNAc)-PD but not with mannose-PD, the mutant CEL-I showed relatively weak but definite affinity for mannose-PD. These results indicated that the QPD and EPN motifs play a significant role in the carbohydrate-recognition mechanism of CEL-I, especially in the discrimination of galactose and mannose. Additional mutations in the recombinant CEL-I binding site may further increase its specificity for mannose, and should provide insights into designing novel carbohydrate-recognition proteins.

Keywords: Lectin, sea cucumber, carbohydrate binding, dendrimer.

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Article Details

Year: 2013
Page: [796 - 801]
Pages: 6
DOI: 10.2174/0929866511320070009
Price: $58

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