title: Crystallization of Galectin-8 Linker Reveals Intricate Relationship between the N-terminal Tail and the Linker.
abstract: Galectin-8 (Gal-8) plays a significant role in normal immunological function as well as in cancer. This lectin contains two carbohydrate recognition domains (CRD) connected by a peptide linker. The N-terminal CRD determines ligand binding specificity, whereas the linker has been proposed to regulate overall Gal-8 function, including multimerization and biological activity. Here, we crystallized the Gal-8 N-terminal CRD with the peptide linker using a crystallization condition that contains Ni2+. The Ni2+ion was found to be complexed between two CRDs via crystal packing contacts. The coordination between Ni2+and Asp25 plays an indirect role in determining the structure of β-strand F0 and in influencing the linker conformation which could not be defined due to its dynamic nature. The linker was also shortened in situ and crystallized under a different condition, leading to a higher resolution structure refined to 1.08 Å. This crystal structure allowed definition of a short portion of the linker interacting with the Gal-8 N-terminal tail via ionic interactions and hydrogen bonds. Observation of two Gal-8 N-terminal CRD structures implies that the N-terminal tail and the linker may influence each other's conformation. In addition, under specific crystallization conditions, glycerol could replace lactose and was observed at the carbohydrate binding site. However, glycerol did not show inhibition activity in hemagglutination assay.
authors.affiliation: Jilin Province Key Laboratory on Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, China. siyl071@nenu.edu.cn.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Si
authors.affiliation: Jilin Province Key Laboratory on Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, China. wangy147@nenu.edu.cn.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Jilin Province Key Laboratory on Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, China. gaoj466@nenu.edu.cn.
authors.forename: Jin
authors.initials: J
authors.lastname: Gao
authors.affiliation: Jilin Province Key Laboratory on Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, China. songcy738@nenu.edu.cn.
authors.forename: Chenyang
authors.initials: C
authors.lastname: Song
authors.affiliation: Jilin Province Key Laboratory on Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, China. fengsq104@nenu.edu.cn.
authors.forename: Shiqiong
authors.initials: S
authors.lastname: Feng
authors.affiliation: Jilin Province Key Laboratory on Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, China. zhouyf383@nenu.edu.cn.
authors.forename: Yifa
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Jilin Province Key Laboratory on Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, China. taigh477@nenu.edu.cn.
authors.forename: Guihua
authors.initials: G
authors.lastname: Tai
authors.affiliation: Jilin Province Key Laboratory on Chemistry and Biology of Natural Drugs in Changbai Mountain, School of Life Sciences, Northeast Normal University, Changchun 130024, China. sujy100@nenu.edu.cn.
authors.forename: Jiyong
authors.initials: J
authors.lastname: Su
mesh_terms: D000818:Animals; D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry; D002645:Chickens; D003451:Cryoprotective Agents / Q000494:pharmacology; D003460:Crystallization; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D004903:Erythrocyte Aggregation / Q000187:drug effects; D037161:Galectins / Q000737:chemistry* / Q000378:metabolism*; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D002241:Carbohydrates; D003451:Cryoprotective Agents; D037161:Galectins
keywords: galectin linker crystallization; galectin-8 N-terminal CRD crystal structure; glycerol; hemagglutination assay