A direct structure determination using lectin-carbohydrate complex

2016 Fiscal Year Final Research Report

• Project/Area Number: 15K12750
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Chemical biology
• Research Institution: Hokkaido University
• Principal Investigator: Sakai Ryuichi 北海道大学, 水産科学研究院, 教授 (20265721)
• Research Collaborator: TANAKA Yoshikazu 北海道大学, 大学院・先端生命科学研究院, 准教授 (20374225)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: レクチン / X-線構造解析 / 直接構造決定

Outline of Final Research Achievements

Lectins, carbohydrate binding proteins, bind to sugars. We have isolated a galactose binding lectin CchG from the marine sponge Cinachyrella sp. that forms a rigid tetramer in the crystalline state. If the lectin-carbohydrate complex can be crystallized and its structure solved, the structure of the carbohydrate bind to the protein will be visualized. We extended this idea to determine the structure of glycosylated small molecules; that is, if a small molecule was glycosylated with the sugar that can bind to the lectin, the structure of the glycoside would be visualized directly by X-ray crystallography at the atomic level.
We thus tested our concept by synthesizing 1-fluoro-2,4-dinitrobenzene-5-(1-aminolacoside) (LacDNFB) which can readily couple with amino acids. In crystallization of CchG-lactose, CchG-LacDNFB, and CchG-LacDNFB-alanine complexes, and crystal structure for CchG-lactose showing that +1-end of the sugar had a space to hold molecule to be visualized, was solved.

Free Research Field

水産科学